Question:

self build solar water heater
. Am. Sept 1990 (I think I got the year right… The ‘Energy Issue’ at any rate…) shows that far and away the largest use of oil is in transportation (I’ve forgotten the exact numbers… I posted them contemporaniously with the article … but it was something like 75%).self build solar water heater
I used to use this as ‘evidence’ that nuclear could not replace oil in the economy… Until I discovered the work done by VW on the economics of methanol production using nuclear process heat.  That showed you COULD substitute nuclear for oil given the desire and time, and at a reasonable price too…

What’s a reasonable price?self build solar water heater

Response:

I used to use this as ‘evidence’ that nuclear could not replace oil in the economy… Until I discovered the work done by VW on the economics of methanol production using nuclear process heat.self build solar water heater
That showed you COULD substitute nuclear for oil given the desire and time, and at a reasonable price too… What’s a reasonable price?

About the same per BTU, in real terms, as gasoline during the oil embargo years, or a little lower.  That was about $1.50 in 1975 or so dollars (or about $2.50 to $3/gallon today based on a wild guess as to inflation and technological change…).self build solar water heater
I found a reference to the VW paper in a book titled “Methanol, and Other Ways Around the Gas Pump” or something like that.  I still have the book at home.  With ‘reasonable’ estimates of cost factors they came up with a competitive cost vis-a-vis gasoline.  Then the bottom fell out of the crude market…  Their work was done on a coal based feed stock, though today natural gas would be used due to the low prices.self build solar water heater

Response:

self build solar water heater
Amory Lovins, the energy guru of the Rocky Mountain Institute, thinks the simplest solutions are best. The man who coined the term “negawatt” for energy that is conserved rather than generated, likes caulk guns. A couple years ago, he told Popular Science magazine, “We wouldn’t have needed a single drop [of oil] from the [Persian] Gulf last year.self build solar water heater
Instead of naval guns, we could have mobilized caulk guns.

And he’s wrong, and a fool for having said that to a reporter.  Caulking guns are used to seal homes.  Homes are mostly heated by natural gas with electricity, oil and propane coming in well behind.  Caulking up a home heated by natural gas saves no oil, and neither does it help if the home uses a heat pump in an area with coal-fired or nuclear electricity. Lovins should be smart enough to know that oil is not interchangeable with natural gas, coal or nuclear.  Oil is mostly used to make fuels for transportation.  For Lovins to say such a thing for international publication means he is either stupid or dishonest,self build solar water heater
and IMHO, it is stupid to risk one’s reputation for the sake of a cheap shot.

Response:

=And he’s wrong, and a fool for having said that to a reporter.  Caulking =guns are used to seal homes.  Homes are mostly heated by natural gas =with electricity, oil and propane coming in well behind. Evidence in support of that claim? Disclaimer:  Hey, I understand VAXen and VMS.  That’s what I get paid for.  My understanding of astronomy is purely at the amateur level (or below).  So unless what I’m saying is directly related to VAX/VMS, don’t hold me or my organization responsible for it.  If it IS related to VAX/VMS, you can try to hold me responsible for it, but my organization had nothing to do with it. self build solar water heater

Response:

self build solar water heater
by Robert Bryce American homes are profligate users of energy. Whether it’s the electric water heater or the gas range, our appliances use copious amounts of power. Saving energy can be as simple as turning off a light or as complex as installing a solar water heater. It all depends on how much you spend, which then determines how much money you will save.         For instance, replacing your gas water heater with a solar water system doesn’t make sense unless you plan to stay in your home more than seven years. The payback on the solar heater simply takes too long. On the other hand, an energy efficient compact fluorescent light bulb costs only $12 and pays for itself very quickly. self build solar water heater
A whole new breed of energy efficient appliances have begun appearing in the American marketplace, ranging from the new Energy Star computers to the new super efficient refrigerators. Staber Industries, an Ohio company, will soon begin production of a horizontal axis, top-loading, high-speed-spin clothes washer that cuts hot water usage by more than half. A similar technology developed in Florida uses no detergent, operates in cold water and recycles almost all of the water used in the wash cycle.         After pulling your clothes from the super-efficient washer, you can quick-dry them in a new microwave clothes dryer. The Electric Power Research Institute and several manufacturers have been working on this new use for the microwave for four years and are hoping to introduce a commercial model later this year.         Lighting consumes about 25% of all the electricity used in the U.S. Studies done by the Rocky Mountain Institute show that nearly all that electricity could be saved if the country retrofitted the lighting equipment now in place. Compact fluorescent bulbs last ten times longer and use 75-85% less energy than incandescent bulbs. Halogen lights also are more efficient than incandescents.         The most energy intensive activities in the home involve cooling. Air conditioning and refrigeration require massive amounts of power. In 1990, we Texans spent some $4 billion on electricity to cool our homes. Nationwide, according to the Energy Information Administration, the commercial sector spent $47.8 billion on electricity for air conditioning and cooling. Technological advances are improving the efficiency of cooling systems. But most cooling equipment depends on ozone-depleting chemicals which were banned by an international agreement known as the Montreal Protocols. The replacements for CFCs are expensive and many of the new cooling agents are less efficient than their predecessors.         Numerous companies are developing more efficient air conditioning units. One Austin company, Allied Energy, produces a mini-cooling tower system which dramatically increases air conditioner efficiency. Most cooling systems use air to cool the Freon or cooling agent. Mac Word, owner of Allied Energy, points out that water absorbs more heat than air. Thus, when used in a cooling tower, it increases cooling capacity with a smaller motor and decreases pressure in the system. Normally used for large buildings, the idea requires a bit more plumbing than conventional systems. But the efficiency should make up for increased complexity. Most central A/C units have EERs (energy efficiency rating) of 8 to 12. Allied’s units claim EERs of 16 to 18.5. [I personally have one of these installed in my home and can atteset to  efficiency -dewey ]         De-humidification systems also increase cooling efficiency. Increasingly popular in supermarkets, where low humidity is essential (high humidity causes frost build up on frozen foods), decreasing the amount of moisture in a building allows the cooling systems to work more efficiently because the system doesn’t have to work as hard to take the moisture out of the air. These systems are just becoming available to the residential market. Southern Union Gas Co. is working on development of this technology; contact them for more info.         An ancient idea, wind towers, can also help reduce air conditioning costs.  Developed in ancient Egypt, the towers are common in the Middle East. Extending far above the roof line, the tower allows hot interior air to escape while directing cooler air into the building. The design relies on convection rather than mechanical means to move the air. Wind towers, wind scoops, and other ancient, low-tech cooling ideas are now being utilized in a few projects in Texas and other hot areas of the U.S. This may not be practical for most applications inside the city, but consult publications such as Earthword,self build solar water heater
or the Real Goods catalogs, for more information on this and other options, such as photovoltaic cells or solar water heaters.   Refrigerators have also been getting lots of attention. “Refrigerators have the biggest impact for year-round energy savings in the residential sector,” says a recent report by the Center for Energy Studies at the University of Texas. The study showed that residential and commercial energy usage could be reduced by 25% if energy conservation became a priority. The report, titled, “Opportunities for Energy Efficiency in Texas,” found that more than a dozen of the electrical generating units now being planned could be eliminated if Texas utilities adopted energy efficiency as their main goal.         Much of the focus on energy efficient refrigerators has occurred because as UT scientist Jay Zarnikau points out, “It is the single measure with the greatest potential savings because they [refrigerators] run night and day year round.”         Perhaps the most notable and highest profile project in the sector was the so-called “Golden Carrot” refrigerator program, which encouraged manufacturers to develop an environmentally friendly refrigerator. 24 utility companies joined forces in the Super Efficient Refrigerator Program which required manufacturers to develop a high-efficiency refrigerator using no CFC’s. Whirlpool beat out 13 other competitors last summer when the consortium announced the company had won the $30 million prize. Some of the advances made by the contest are already benefitting consumers. For instance, in 1992, the average 20 cubic foot Whirlpool refrigerator used $72 worth of electricity per year. One year later, the same model used $51 worth of power.         You probably won’t want to replace your fridge until you have to. But if you do, shop around and keep an eye on the yearly energy cost sticker. Whirlpool and KitchenAid appliances are probably the best in terms of energy efficiency. They are available at many local appliance dealers.         Other products that can reduce your home energy consumption include halogen lights which use less power than incandescent, high efficiency air conditioners, solar screens, and old-fashioned insulation. All of these products can help save energy. Their payback depends on how much energy consumers use and how much the products are used.         Shade trees are another good idea. They are cheap and help absorb solar rays. They also help reduce the “heat island” effect common in urban areas.         Tankless (also called demand) water heaters, have been used in Europe for decades. More efficient than conventional heaters, they can reduce water heating costs by a third. The heaters are available through the Sears catalog, Real Goods, or they can be ordered through some local plumbing supply stores.         Amory Lovins, the energy guru of the Rocky Mountain Institute, thinks the simplest solutions are best. The man who coined the term “negawatt” for energy that is conserved rather than generated, likes caulk guns. A couple years ago, he told Popular Science magazine, “We wouldn’t have needed a single drop [of oil] from the [Persian] Gulf last year. Instead of naval guns, we could have mobilized caulk guns.self build solar water heater

Response:

Question:

closed loop solar  Panels of build solar water heater panels home madeHaving read many of the posts in this forum, I can predict a great number of rolling eyes and long sighs while reading this question… your knowledge is vast and technical, and I stand before you humble, and curious.  Please complete the following statement: A simple collector is best made of ______, and size (thickness) ______ matter(s). I plan to build a small solar water heater, using copper tubing mounted to a collector plate, and need to know how effeciency is affected by the thickness of the tubing walls and collector plate, and material of the collector plate. Thanks in advance. closed loop solar panels home made

Response:

Having read many of the posts Panels of build solar water heater in this forum,closed loop solar panels home made I can predict a great number of rolling eyes and long sighs while reading this question… your knowledge is vast and technical, and I stand before you humble, and curious.  Please complete the following statement: A simple collector is best made of ______, and size (thickness) ______ matter(s). I plan to build a small solar water heater, using copper tubing mounted to a collector plate, and need to know how effeciency is affected by the thickness of the tubing walls and collector plate, and material of the collector plate. Thanks in advance. closed loop solar panels home made

The thinner the copper is, the faster the heat tranfer to your fluid. When calculating for the collector plate, the thickness is the distance from the tube to the edge. If the plate joins two tubes, it would be the middle distance to the tube

Response:

closed loop solar panels home made Not sure if your still watching, but I ran across the following material    that might help with your question: The numbers in the table below indicate the efficiency of the collector plate in transfering heat to the collector tubes — 1.0 is perfect:                       Tube spacing in inches                       3 inch        7 inch 0.04 thick Copper    1.0            0.93 0.02 thick copper    0.98           0.89 0.04 thick alum      0.99           0.92 0.02 thick alum      0.97           0.85 This assumes good thermal contact between the tubes and the collector plate. I think copper is a good material for long life, low corrosion etc. It looks like you don’t pay much of a penelty in efficiency for tube spacings up to 6 or 7 inches, and collector plate thickness down to 0.02. Gary – Hide quoted text — Show quoted text – Having read many of the posts in this forum, I can predict a great number of rolling eyes and long sighs while reading this question… your knowledge is vast and technical, and I stand before you humble, and curious.  Please complete the following statement: A simple collector is best made of ______, and size (thickness) ______ matter(s). I plan to build a small solar water heater, using copper tubing mounted to a collector plate, and need to know how effeciency is affected by the thickness of the tubing walls and collector plate, and material of the collector plate.closed loop solar panels home made

Response:

closed loop solar panels home made Our company is a distributor for Solar Thermal panels from Thermo Dynamics. They have some of the most advanced panels in the world and have over 20 years of research and experience. Their panels use an aluminum fin about 5.5″ wide and 0.02″ thick. There is also a copper tube that Panels of build solar water heater is metallurgically bonded to the aluminum fin so that there is high heat conductivity and no chance of corrosion between the two metals. You can see more details of this in the following document: www.heatwithsolar.com/products/G_Series_tech.pdf  The end result is a collector with an efficiency FR value of 74%, which is pretty good for a flat-plate collector. I mention these things so that you can get an idea what the big manufacturers are doing. Hopefully it will be helpful in your project. In our support for the hobbyist, we can sell you the fins we use separately and you can construct them into collectors and arrays. In Canadian $$, the solar fins sell for $46 per square meter and solar fins assembled with 3/4″ headers (4 ft x 8ft) sell for $257 each. Hope this information is helpful without sounding too much like a sales pitch.Panels of build solar water heater

Panels of build solar water heater,  Not sure if your still watching, but I ran across the following material    that might help with your question: The numbers in the table below indicate the efficiency of the collector plate in transfering heat to the collector tubes — 1.0 is perfect:                       Tube spacing in inches                       3 inch        7 inch 0.04 thick Copper    1.0            0.93 0.02 thick copper    0.98           0.89 0.04 thick alum      0.99           0.92 0.02 thick alum      0.97           0.85 This assumes good thermal contact between the tubes and the collector plate. I think copper is a good material for long life, low corrosion etc. It looks like you don’t pay much of a penelty in efficiency for tube spacings up to 6 or 7 inches, and collector plate thickness down to 0.02. Gary Having read many of the posts in this forum, I can predict a great number of rolling eyes and long sighs while reading this question… your knowledge is vast and technical, and I stand before you humble, and curious.  Please complete the following statement: A simple collector is best made of ______, and size (thickness) ______ matter(s). I plan to build a small solar water heater, using copper tubing mounted to a collector plate, and need to know how effeciency is affected by the thickness of the tubing walls and collector plate, and material of the collector plate. Thanks in advance. closed loop solar panels home made

Response:

Panels of build solar water heater

That’s a bit misleading. Your 74% efficiency number, while technically true, is not very useful as the temperature rise is zero degrees C. What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. Duane —     Home of the $35 Solar Tracker      Receiver    http://www.redrok.com/electron.htm#led3X [*]   Powered by                          //|  Thermonuclear   Solar Energy from the Sun / | Energy (the SUN)                  /  /  | Red Rock Energy                   /   /   | Duane C. Johnson   Designer      /   /    | 1825 Florence St  Heliostat,Control,& Mounts | White Bear Lake, Minnesota    ===   /    | USA      55110-3364                ===     | (651)426-4766        use Courier New Font  | http://www.redrok.com  (Web site)          === Panels of build solar water heater

Response:

Here is a re-post of my reply for all to see. Hi Duane: You are right that the 74% can be misleading. It is only an indicator of how well the solar fins, collector box, glazing and insulation will operate as a “set” in a completed solar collector. The de-rating curve that was also in the document I referenced actually shows the Panels of build solar water heater reduced performance based on the temperature differential of the collector fluid and the outside air temperature. h = 0.738 – 5.247(Ti – Ta)/G Perhaps better measurements to point out would have been the solar fin’s solar absorptivity of 95 % and its infrared emissivity of 25%. This is based on solar fins that are painted. We also use solar fins that have a Anodic-Cobalt treated surface with slightly lower absorptivity but much lower emissivity (92% and 15% respectively). Regards, Stephen CummingerPanels of build solar water heater

Response:

Panels of build solar water heater

You are right that the 74% can be misleading… The de-rating curve… shows the reduced performance based on the temperature differential of the collector fluid and the outside air temperature. h = 0.738 – 5.247(Ti – Ta)/G with 0.0667 kg/s of inlet water at Ti (C), and (Ti-Ta)/G in Cm^2/W… Duane writes: What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. How would you answer this question, with a 50 C average water temp? closed loop solar panels home made Panels of build solar water heater

Response:

I think that I left out an important part. My apologies upfront. The subject of collector efficiency can be a bit confusing, so I’ll attempt to explain it in a bit more detail. Collector efficiency = Solar Energy Collected / Solar Energy Available. This is what I am referring to when I talk about efficiency. I trust we can all agree with this starting point. The simplified equation for the amount of energy you can collect is: Q = FR*G – FrUL ( Ti- Ta);  This first term is the solar gain and the second represents the heat losses of the collector to the outside air. FR = 0.74 (for the collectors I mentioned). This number has no units of measurement. G = Solar radiation available. This can be in several different units of measure. Watts/m^2 is common for instantaneous or average hourly figures. Since Watts = Joules/second, you can see that these units really describe the rate/speed that energy that can be collected. For solar system sizing purposes, the total amount of solar energy per day that is available can be very useful. This can be expressed in kilo-watt hours or Joules. 1 kwhr = 1000*60*60 Joules. FrUL = 5.247 W/m^c/Degree C (for the collectors I mentioned).  This represents the rate of heat lost to the outside air from the heated fluid circulating through the collector. Again, the rate of heat loss * time = energy lost. (Ti – Ta) = the temperature difference between the average fluid temperature in the collector and the outside air. We use the average daytime temperature in our calculations as that is when the fluid would be circulating.  Panels of build solar water heater Putting this all together for a typical day in Richfield, Missouri that has average total Solar Radiation of 6.4 Kwhr/m^2 in May with an average daytime temperature of  10.6 C and 10 hours of good Solar Collection time (fluid circulation): Q = 0.74 * 6400 Watts-hour/m^2*3600sec/hour  - 5.247 Watts/m^2/C*(50 C – 10.6 C) * 10 hours*3600sec/hour   =  9607 Kilo-Joules (1 hour = 3600 seconds, 1 Watt = 1 Joule/sec) Solar Energy Available = 6400 Watt-hours * 3600 sec/hour = 23040 Kilo – Joules Collector Efficiency then = 9607 / 23040 = 41.6% This assumes that the input fluid temperature is close to 50 C at all times. That may be true for some applications, but not for typical domestic hot water (DHW) applications. In those cases the fluid temperature would be very low in the morning and high by the end of the day. That would make the average fluid temperature to be closer to 30 C, resulting in an efficiency of 57.6%. Different applications can get different performance out of the same collectors. This is why the ratings for FR and FrUL are so important in comparing different Solar Collectors. In summary, thanks Nick for picking up my error. — Regards, www.heatwithsolar.com

- Hide quoted text — Show quoted text – Based on Richfield, Missouri with an average (yearly) ground-level radiation of 5300 Watts/m^2/day… Watts per day? , the efficiency equation becomes 0.738-5.247*(60)/5300 = 67.8%. The following link has some info on how the efficiency ratings are determined, if anyone is interested. http://www.fsec.ucf.edu/solar/testcert/collectr/gp6ops.htm You’ve ducked Duane’s question again Stephen, and this time you got the numbers AND the units AND the equation wrong, while coming up with an overly optimistic answer. You may have a brilliant career as a politician. Can you find someone at the factory who actually understands Duane’s question and post a correct answer here? You are right that the 74% can be misleading… The de-rating curve… shows the reduced performance based on the temperature differential of the collector fluid and the outside air temperature. h = 0.738 – 5.247(Ti – Ta)/G with 0.0667 kg/s of inlet water at Ti (C), and (Ti-Ta)/G in Cm^2/W… Duane writes: What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. How would you answer this question, with a 50 C average water temp? Nick

Response:

I think that I left out an important part. Panels of build solar water heater My apologies upfront. The subject of collector efficiency can be a bit confusing, so I’ll attempt to explain it in a bit more detail. closed loop solar panels home made

It seems to me that you are the person who is confused Collector efficiency = Solar Energy Collected / Solar Energy Available. This is what I am referring to when I talk about efficiency. I trust we can all agree with this starting point.

I’d say “power,” vs energy. Collector efficiency is an instantaneous parameter, hot water output power divided by solar input power, with a particular flow rate and inlet temperature. The simplified equation for the amount of energy you can collect is: Q = FR*G – FrUL ( Ti- Ta);  This first term is the solar gain and the second represents the heat losses of the collector to the outside air… G = Solar radiation available. This can be in several different units of measure. Watts/m^2 is common for instantaneous or average hourly figures. closed loop solar panels home made

And collector efficiency calculations. For solar system sizing purposes, the total amount of solar energy per day that is available can be very useful…

That’s a different subject. FrUL = 5.247 W/m^c/Degree C (for the collectors I mentioned). Panels of build solar water heater

FrUL = 5.247 W/m^2/Degree C? (Ti – Ta) = the temperature difference between the average fluid temperature in the collector and the outside air. We use the average daytime temperature in our calculations as that is when the fluid would be circulating.

Ti is the INLET (i for inlet) vs the average fluid temperature, which would be higher. Putting this all together for a typical day in Richfield, Missouri that has average total Solar Radiation of 6.4 Kwhr/m^2 in May with an average daytime temperature of  10.6 C and 10 hours of good Solar Collection time (fluid circulation):

Duane didn’t ask about Richfield, and the solar intensity on the panel and water and air temps can vary a lot over 10 hours, which makes this kind of calculation meaningless: Q = 0.74 * 6400 Watts-hour/m^2*3600sec/hour  - 5.247 Watts/m^2/C*(50 C – 10.6 C) * 10 hours*3600sec/hour   =  9607 Kilo-Joules

Very mysterious… I can’t imagine what was going on in your brain when your fingers typed that. The units don’t even work. Where did the m^2 go? You might say the average solar power is 6.4kWh/m^2/10hours = 640 W/m^2 (altho it isn’t because the sun angle and intensity vary over the day) and estimate the efficiency as 0.738-5.247*(50-10.6)/640 = 0.41, but that would be a very gross approximation. Solar Energy Available = 6400 Watt-hours * 3600 sec/hour = 23040 KiloJoules Panels of build solar water heater

That part looks OK, for a square meter. Collector Efficiency then = 9607 / 23040 = 41.6%

Very mysterious. This assumes that the input fluid temperature is close to 50 C at all times.

Duane didn’t ask about an input fluid temperature. He asked about an average fluid temperature. To answer his question, you might do some sort of calculation involving the fluid flow rate and the collector area to find the outlet temperature, then average the inlet and outlet temps. That may be true for some applications, but not for typical domestic hot water (DHW) applications. In those cases the fluid temperature would be very low in the morning and high by the end of the day.

With an undersized heat storage tank. That would make the average fluid temperature to be closer to 30 C, resulting in an efficiency of 57.6%. closed loop solar panels home made

But your efficiency equation uses an inlet vs average fluid temp. You’ve ducked Duane’s question a third time, Stephen. You may have a brilliant career as a politician. Can you find someone at the factory who actually understands Duane’s question and post a correct answer here? Duane writes: What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. How would you answer this question, with a 50C average water temp? Panels of build solar water heater

Say water goes in at temp Ti, which is less than 50C, at the flow rate specified on your data sheet, and the sun on the panel is 1000 W/m^2…Panels of build solar water heater

Response:

(Ti – Ta) = the temperature difference between the average fluid temperature in the collector and the outside air…

That’s apparently how Europeans spec collector efficiency, but your Ti is the inlet vs average temp. Putting this all together for a typical day in Richfield, Missouri…

Duane didn’t ask about Richfield… This assumes that the input fluid temperature is close to 50 C at all times. closed loop solar panels home made

Duane asked about an average vs input fluid temperature. To answer his question, you might do some sort of calculation involving the fluid flow rate and the collector area to find the outlet temperature, then average the inlet and outlet temps. Can you find someone at the factory who actually understands Duane’s question and post a correct answer here?

Peter Allen understands Duane’s question. Duane writes: What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. How would you answer this question, with a 50C average water temp?

Say water goes in at temp Ti, which is less than 50C, at the flow rate specified on the data sheet, and the sun on the panel is 1000 W/m^2… With 0.0687 kg/s of water flow and 2.78 m^2 of solar aperture and efficiency E = 0.738-5.247(Ti-10)/1000 = 0.6855-0.005247Ti (1) and (Ti+To)/2 = 50 (2), To = Ti+2.78×1000E/(0.0687kg/sx4.19kJ/kg-c) = Ti+9.66E (3). Substituting To = 100-Ti (2) on the left side of (3) and (1) on the right side makes 100-Ti = Ti+9.66(0.6855-0.005247Ti), so Ti = 47.91 C and E = 0.434, for a 43.4% collection efficiency. Peter says (2) isn’t quite accurate because the water gains more heat in the first half of the collector than in the second half, since it is cooler in the first half and loses less heat to the outdoors. Nick

Response:

Sounds like Peter and I were very close in our estimates; 43% vs. 41%. Not bad. Regards, Stephen Cumminger www.heatwithsolar.com

Panels of build solar water heater the temperature difference between the average fluid temperature in the collector and the outside air… That’s apparently how Europeans spec collector efficiency, but your Ti is the inlet vs average temp. Putting this all together for a typical day in Richfield, Missouri… Duane didn’t ask about Richfield… This assumes that the input fluid temperature is close to 50 C at all times. Duane asked about an average vs input fluid temperature.closed loop solar panels home made To answer his question, you might do some sort of calculation involving the fluid flow rate and the collector area to find the outlet temperature, then average the inlet and outlet temps. Can you find someone at the factory who actually understands Duane’s question and post a correct answer here? Peter Allen understands Duane’s question. Duane writes: What is the efficiency of your collector at a more useful temperature rise? Let’s say the temperature rise is 60C (108F):  50C (122F) average water temperature. -10C ( 14F) ambient temperature. How would you answer this question, with a 50C average water temp? Say water goes in at temp Ti, which is less than 50C, at the flow rate specified on the data sheet, and the sun on the panel is 1000 W/m^2… With 0.0687 kg/s of water flow and 2.78 m^2 of solar aperture and efficiency E = 0.738-5.247(Ti-10)/1000 = 0.6855-0.005247Ti (1) and (Ti+To)/2 = 50 (2), To = Ti+2.78×1000E/(0.0687kg/sx4.19kJ/kg-c) = Ti+9.66E (3). Substituting To = 100-Ti (2) on the left side of (3) and (1) on the right side makes 100-Ti = Ti+9.66(0.6855-0.005247Ti), so Ti = 47.91 C and E = 0.434, for a 43.4% collection efficiency. Peter says (2) isn’t quite accurate because the water gains more heat in the first half of the collector than in the second half, since it is cooler in the first half and loses less heat to the outdoors. Nick

Response:

Sounds like Peter and I were very close in our estimates; 43% vs. 41%. Not bad. closed loop solar panels home made

Panels of build solar water heater

Response:

Question:

Is anyone completely off-the-grid, solar,how to build solar water heater  etc… without a generator or the need for one? If yes, please tell me alittle about your set-up, like house sq ft? earthsheltered?  how much wattage in arrays PV?  about how much watts used? I’m trying to get an idea of what I will need and be in for when I do build my house. Thanks, Greg Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away.   You think it’s bad now, what til the criminals know you don’t have one!!!! how to build solar water heater

Response:

Greg, I don’t know where you are getting your information from but crime rates in Canada have been going down since the late 1980’s – early 1990’s. I don’t think Canadians would appreciate you spreading lies about them. — RJG “Where all think alike, no one thinks very much”how to build solar water heater   Is anyone completely off-the-grid, solar, etc… without a generator or the need for one? If yes, please tell me alittle about your set-up, like house sq ft? earthsheltered?  how much wattage in arrays PV?  about how much watts used? I’m trying to get an idea of what I will need and be in for when I do build my house. Thanks, Greg Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away.   You think it’s bad now,how to build solar water heater  what til the criminals know you don’t have one!!!! VOTE FOR BUSH!!!

Response:

how to build solar water heater  I don’t know where you are getting your information from but crime rates in Canada have been going down since the late 1980’s – early 1990’s. I don’t think Canadians would appreciate you spreading lies about them. — RJG “Where all think alike, no one thinks very much” – Walter Lippman Is anyone completely off-the-grid, solar, etc… without a generator or the need for one? If yes, please tell me alittle about your set-up, like house sq ft? earthsheltered?  how much wattage in arrays PV?  about how much watts used? I’m trying to get an idea of what I will need and be in for when I do build my house. Thanks, Greg Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away.   You think it’s bad now, what til the criminals know you don’t have one!!!! how to build solar water heater

It was on TV in here in the US that crime with guns went up! Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away.   You think it’s bad now, what til the criminals know you don’t have one!!!!how to build solar water heater

Response:

It was on TV in here in the US that crime with guns went up!

Oh well then, if it was on TV then it must be THE TRUTH! Ye’r insultin’ a whole lot a people here son, mabbe you otta do some checkin’ on yer own, eh? Or are you sayin’ that because there are more guns in Canada now there’s more crime with guns.how to build solar water heater  Is that what yer sayin’?

Response:

There are times like today that I am getting neither sun no wind,how to build solar water heater  so I prefer to just crank up my generator. I don’t use it much so I bought an inexpensive gas unit. It all depends on your finances; did you have enough money to buy lots of batteries, which will allow you to go a couple of days? Is your lifestyle such you can just run a couple of lights and maybe give up the TV for the day etc? Did you get rid of the major power consumers so your power usage is properly matched to the system you have? It’s a complex question. Chris Olance – Hide quoted text — Show quoted text – Is anyone completely off-the-grid, solar, etc… without a generator or the need for one? If yes, please tell me alittle about your set-up, like house sq ft? earthsheltered?  how much wattage in arrays PV?  about how much watts used? I’m trying to get an idea of what I will need and be in for when I do build my house. Thanks, Greg Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away. You think it’s bad now, what til the criminals know you don’t have one!!!!how to build solar water heater

Response:

It was on TV in here in the US that crime with guns went up! Oh well then, if it was on TV then it must be THE TRUTH! Ye’r insultin’ a whole lot a people here son, mabbe you otta do some checkin’ on yer own, eh? Or are you sayin’ that because there are more guns in Canada now there’s more crime with guns. Is that what yer sayin’?

Don’t mean to insult anyone,how to build solar water heater  pretty sure CNN had reported that crime involving guns (of course must be illegal guns) has rise 38% since the ban.

Response:

-how to build solar water heater  It was on TV in here in the US that crime with guns went up! Oh well then, if it was on TV then it must be THE TRUTH! Ye’r insultin’ a whole lot a people here son, mabbe you otta do some checkin’ on yer own, eh? Or are you sayin’ that because there are more guns in Canada now there’s more crime with guns. Is that what yer sayin’? Don’t mean to insult anyone, pretty sure CNN had reported that crime involving guns (of course must be illegal guns) has rise 38% since the ban.

That would follow the typical trend of our own areas which have reduced the number of legal weapons. Several years ago I read an interview with a convicted carjacker/ armed robber from Florida, he said that he deliberately targeted rental vehicles because he felt safer knowing that it would contain non-residents.how to build solar water heater   Florida legalized concealed handgun carry several years ago, so he was concerned that other potential “victims” might be armed.  Of course, his own gun was already “banned”, as it is illegal for a felon to have one. Somehow he had it anyway ….. Martin Before you buy.

Response:

Greg, I don’t know where you are getting your information from but crime rates in Canada have been going down since the late 1980’s – early 1990’s. I

Umm, you’re both right.  Crime rates hoverall ave been dropping, but the rate of crimes with guns has _risen_ because the criminals know that their victims will be unarmed.  Why do you think school shootings outnumber donut shop shootings?  8*) — ComputerSmiths Consulting,how to build solar water heater

Response:

how to build solar water heater  You are quite right, Greg’s propaganda does say: “if you want to end up like Australia and Canada, with crime rate with guns has risen since average citizens guns were taken away.” My points are: 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up). [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?] 2)Average citizens guns have never been taken away.(in Canada anyway, I don’t know about Australia) Over to you Mr. Smith and Greg, — RJG “Where all think alike, no one thinks very much” – Walter Lippman – Hide quoted text — Show quoted text – Greg, I don’t know where you are getting your information from but crime rates in Canada have been going down since the late 1980’s – early 1990’s. I Umm, you’re both right.  Crime rates hoverall ave been dropping, but the rate of crimes with guns has _risen_ because the criminals know that their victims will be unarmed.  Why do you think school shootings outnumber donut shop shootings?  how to build solar water heater

Response:

[Rathole alert, this is probably way off topic for this newsgroup, please kill this thread if it bothers you.  I could make a claim for homepower advocates being advocates of other kinds of liberty, but I won't bother.] 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up).

You have a common misconception, that gun laws will be able to significantly influence the number of illegal guns in circulation, and will reduce gun crime.  Gun laws only apply to The Good Guys (TM), so restrictive gun laws shift the balance of power from the good guys (who give them up) to the bad guys (who now know the good guys are unarmed).  See “More Guns, Less Crime” by John Lott, who shows that in states where honest citizens are allowed to carry concealed weapons, gun crime is  _reduced_, apparently because the criminals don’t know if their intended victim is armed or not, and many attempted crimes aren’t completed when the victim successfully resists.  [Question, do you think you are more or less likely to be injured by a criminal if you submit or resist?] [as an aside, is it sensible to assume that if you are supportive of police persons,how to build solar water heater  who are daily in the line of fire! you would want fewer guns around not more?]

As an aside, while I am very supportive of police persons (most of whom are in favor of firearms ownership by honest law-abiding citizens), I don’t see that the number of guns owned by The Good Guys has any clear relationship to shots fired at police officers.  While some guns may be stolen, a reduction in firearms-related crime rate would make life safer for the cop on the beat, and a number of cops have been saved by ordinary citizens with guns.  You won’t read about it in the papers too often, but then the media isn’t without bias, eh? 2)Average citizens guns have never been taken away.(in Canada anyway, I don’t know about Australia)

Sorry, I was under the impression that you used to be able to have pistols in Canada, where now it’s pretty much verboten.  And Canada has recently started requiring gun registration, which historically has led to confiscation.how to build solar water heater

Response:

Taking this off-newsgroup as it doesn’t belong here. I’ll email you privately. You’re misconstruing things. — RJG “Where all think alike, no one thinks very much” – Walter Lippman – Hide quoted text — Show quoted text – [Rathole alert, this is probably way off topic for this newsgroup, please kill this thread if it bothers you.  I could make a claim for homepower advocates being advocates of other kinds of liberty, but I won't bother.] 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up). You have a common misconception, that gun laws will be able to significantly influence the number of illegal guns in circulation, and will reduce gun crime.  Gun laws only apply to The Good Guys (TM), so restrictive gun laws shift the balance of power from the good guys (who give them up) to the bad guys (who now know the good guys are unarmed).  See “More Guns, Less Crime” by John Lott, who shows that in states where honest citizens are allowed to carry concealed weapons, gun crime is  _reduced_, apparently because the criminals don’t know if their intended victim is armed or not, and many attempted crimes aren’t completed when the victim successfully resists.  [Question, do you think you are more or less likely to be injured by a criminal if you submit or resist?] [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?] As an aside, while I am very supportive of police persons (most of whom are in favor of firearms ownership by honest law-abiding citizens), I don’t see that the number of guns owned by The Good Guys has any clear relationship to shots fired at police officers.  While some guns may be stolen, a reduction in firearms-related crime rate would make life safer for the cop on the beat, and a number of cops have been saved by ordinary citizens with guns.  You won’t read about it in the papers too often, but then the media isn’t without bias, eh? 2)Average citizens guns have never been taken away.(in Canada anyway, I don’t know about Australia) Sorry, I was under the impression that you used to be able to have pistols in Canada, where now it’s pretty much verboten.  And Canada has recently started requiring gun registration,how to build solar water heater

Response:

My points are: 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up). [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?]

Why would you think this is a sensible position?  Law abiding citizens with firearms are no extra threat to police, and are arguably safer for having them.  Criminals don’t care about the law (or they would not be criminals in the first place). 2)Average citizens guns have never been taken away.how to build solar water heater  1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up). [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?] Why would you think this is a sensible position?  Law abiding citizens with firearms are no extra threat to police, and are arguably safer for having them.  Criminals don’t care about the law (or they would not be criminals in the first place). 2)Average citizens guns have never been taken away.(in Canada anyway, I don’t know about Australia) Over to you Mr. Smith and Greg, I think you will find a pretty massive gun confiscation going on in Canada right now. how to build solar water heater  When I have finished my project, I expect to be completely off.  Here are the specifics: Family of 6, living in Virginia 3,000 square foot house, 4 BR, 2.5 Bath All major appliances are electric except propane heat for dryer and propane heat for cookstove.  Also, water heater is still on the grid, to be replaced by solar water heater, perhaps Thermomax.  Space heat currently from a Harmon P-61 pellet stove. 2880 Wp solar array at 48V (15 degree elevation summer and 55 degree elevation winter) 2 Trace SW5548 inverters (the house runs fine on only one inverter) NiFe batteries ~20 kWh online now Here are some estimated numbers: We use approximately 10 kWh of electricity per day (excluding the water heater) The water heater uses approximately 10 kWh of electricity per day. We use about 4.5 tons of wood pellets per winter. The well pump is 250 feet underground and draws about 11 A at 120V (it’s a 1/2 HP 240V pump driven through a Trace T-240 transformer) with a starting surge of about 45 A. The house never seems to draw more than 36 A continuous at 120V and generally operates around a few amps. If you would like specific numbers on appliance usage, I have all of this info as well. As you may be able to see, the energy balance comes up a little shy in the wintertime for my situation (I receive an average of about 3 full-sun hours per day in December).  Currently, I am using the grid as backup for the solar should the batteries run out of energy (which does occur).  I am reluctant to add sufficient PV to account for December.  I would like to make up any deficit with an IR PV system on the pellet stove, if possible. Otherwise, it would be nice to have a 200 watt fuel cell with a propane reformer to handle times when there simply isn’t sufficient sun to keep the system working. Anyway, this system is the best I could come up with and still enjoy the conveniences of modern life.  I didn’t arrive at this arrangement overnight, so I hope that it will help you to get a feel for how the problem might be approached.  Not knowing your budget or situation, my approach may or may not be applicable. Regards, George Estep – Hide quoted text — Show quoted text – Is anyone completely off-the-grid, solar, etc… without a generator or the need for one? If yes, please tell me alittle about your set-up, like house sq ft? earthsheltered?  how much wattage in arrays PV?  about how much watts used? I’m trying to get an idea of what I will need and be in for when I do build my house. Thanks, Greg Vote for Gore if you want to end up like Austrailia and Canada, with crime rate with guns has risen since average citizens guns were taken away.   You think it’s bad now, what til the criminals know you don’t have one!!!!how to build solar water heater

Response:

[Rathole alert, this is probably way off topic for this newsgroup, please kill this thread if it bothers you.  I could make a claim for homepower advocates being advocates of other kinds of liberty, but I won't bother.] 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up).

I was told that the way they report certain crimes has changed, and this is one cause of “reduced” crime rates.  The Brits did that a few years ago, about shoplifting, which is a specific field of idiocy for me.  I have been engaged in retail security for 40 years, and so I like to keep abreast of things there.  I am not so well versed in violent crime stats. You have a common misconception, that gun laws will be able to significantly influence the number of illegal guns in circulation, and will reduce gun crime.  Gun laws only apply to The Good Guys (TM), so restrictive gun laws shift the balance of power from the good guys (who give them up) to the bad guys (who now know the good guys are unarmed).how to build solar water heater   See “More Guns, Less Crime” by John Lott, who shows that in states where honest citizens are allowed to carry concealed weapons, gun crime is  _reduced_, apparently because the criminals don’t know if their intended victim is armed or not, and many attempted crimes aren’t completed when the victim successfully resists.  [Question, do you think you are more or less likely to be injured by a criminal if you submit or resist?]

1)  NO crime is completed if the victim SUCCESSVULLY resists. 2) It is worse than just having an armed victim.  You might have an armed bystander who was in some war and has made his peace with death, in this case, the death of the miscreant. Please believe this is a real threat to the violent criminal. WW2, Korea, ‘Nam, and a few other places, have left us with a strong populace of men and women who have been, in the words of Kipling, “Shooted offer a leedle bit.” The hands of the cop are often tied till it is too  late. Many cops never fire a shot in action all their careers. Not so, the NamVets, etc.   That is the real threat.  The nearby armed person who will act.  that covers a lot more people than just the possibly aremd victim. [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?]

I calll this the ann landers (lower case) syndrome.  a form of insanity. ‘fewer guns’ does not support cops. As an aside, while I am very supportive of police persons (most of whom are in favor of firearms ownership by honest law-abiding citizens), I don’t see that the number of guns owned by The Good Guys has any clear relationship to shots fired at police officers.  While some guns may be stolen, a reduction in firearms-related crime rate would make life safer for the cop on the beat, and a number of cops have been saved by ordinary citizens with guns.  You won’t read about it in the papers too often, but then the media isn’t without bias, eh? 2)Average citizens guns have never been taken away.(in Canada anyway, I don’t know about Australia) Sorry, I was under the impression that you used to be able to have pistols in Canadahow to build solar water heater , where now it’s pretty much verboten.  And Canada has recently started requiring gun registration, which historically has led to confiscation.

A fellow trucker came back from CA with the remark thet the gun control is absolute,how to build solar water heater  and he had to leave a pistol at the border. Are we talking about the came CA? “The learned Fool writes his nonsense in better language, but ’tis still nonsense.” B.Franklin ‘Poor Richard Improved’ (1754) Lou H. Semi-Learned, and very foolish, Prolific inventor, now on VP prop and cheap jet for GA Lousy Salesman, Incompetent businessman. (Typical of the Breed) Looking for both around Tulsa OK, USA (need working partner)

Response:

Bob, how much time have you spent in Canada? –

none lately.  whow to build solar water heater  I have 6 PV panels hooked up (I also have an additional 6, 90 watt panels that are still in the box)… but the 6,  90 watt panels that are working, produce about 500 watts per hour, in a good sun… and, and for 4 hours a day,  will produce about  2000 watts per day… when I  get to the point where  I  will  hook  up  the other six panels… I  should  be able  to produce about  4000  watts per  day… which is enough for my frugal needs… So far, 6 panels operates my TV, fan, and house (compact florescent) lights… when I hook up the additional 6 panels… I  should  be  able to add the computer, and a solar type fridge (Conserve 375 which I don’t have, yet,  but it uses about a kw per 24 hour day)…  I  may  need  an additional 6 panels in the future, to operate my clothes washing machine and microwave oven… don’t know yet… My microwave, computer, and washing machine are still on the grid…how to build solar water heater

Response:

how to build solar water heater 1) the crime rate in Canada has been going down on average for the last roughly ten years. (I concede that there are more guns in Canada now and more illegal guns and that the rate of crime where guns have been involved has gone up). [as an aside, is it sensible to assume that if you are supportive of police persons, who are daily in the line of fire! you would want fewer guns around not more?] Why would you think this is a sensible position?  Law abiding citizens with firearms are no extra threat to police, and are arguably safer for having them. Criminals don’t care about the law (or they would not be criminals in the first place).

Au Contraire, mes enfants! The criminals are as concerned with the law as a milk salesman is with refrigeration.  And rightly so.  They don’t want the law to spoil things for them. In another vein, the crims are much against the cits having guns. I grew up in a dry area, in N. Arkansas, and there was a society of bootleggers and state-line bar owners who helped finance anti-booze laws in the state.  They WANTED the state to be dry. FWIW “The learned Fool writes his nonsense in better language, but ’tis still nonsense.” B.Franklin ‘Poor Richard Improved’ (1754) Lou H. Semi-Learned, and very foolish, Prolific inventor, now on VP prop and cheap jet for GA Lousy Salesman, Incompetent businessman. (Typical of the Breed) Looking for both around Tulsa OK, USA (need working partner)

Response:

: That was my house… I have 6 PV panels hooked up (I also have an : additional 6, 90 watt panels that are still in the box)… but the 6,  90 : watt panels that are working, produce about 500 watts per hour, in : a good sun… and, and for 4 hours a day,  will produce about  2000 : watts per day… when I  get to the point where  I  will  hook  up  the : other six panels… I  should  be able  to produce about  4000  watts : per  day… which is enough for my frugal needs… Small nit-pick. You mean 2,000 watt-hours and 4,000 watt-hours respectively. 2KWh/day is not bad. Certainly good for blackout-proofing small stuff and maintaining a charge for a battery cache for the big stuff to make them blackout-resistant. — FOOD FOR THOUGHT: 100 calories are used up in the course of a mile run.how to build solar water heater  The USDA guidelines for dietary fibre is equal to one ounce of sawdust. The liver makes the vast majority of the cholesterol in your bloodstream.

Response:

2KWh/day is not bad. Certainly good for blackout-proofing small stuff and maintaining a charge for a battery cache for the big stuff to make them blackout-resistant.

That’s true… and when I can afford to get the Conserve 375 Fridge… I will hook up the other 6 PV panels… and the fridge will be off line, too…. It may take a third bank of 6 PV’s for anything left over, like the microwave oven… and computer… but… I will have to work on getting the fridge first..how to build solar water heater

Response:

: That’s true… and when I can afford to get the Conserve 375 Fridge… : I will hook up the other 6 PV panels… and the fridge will be off : line, too…. : It may take a third bank of 6 PV’s for anything left over,how to build solar water heater  like the : microwave oven… and computer… but… I will have to work on : getting the fridge first… The mother of all challenges is A/C. That item belongs in the “impossible” column. Apart from that, you are well on your way to going off-grid. — FOOD FOR THOUGHT: 100 calories are used up in the course of a mile run. The USDA guidelines for dietary fibre is equal to one ounce of sawdust. The liver makes the vast majority of the cholesterol in your bloodstream.

Response: