Cooling Solar Panels

Excellent idea ...you could pre-heat your water and cool the panels simultaneously.

That was my idea as well. Apparently solar panels may get a temp rise of 30C above ambinet in full sunlight. Not as much as a purpose built hot water system but still a good pre-heat.

Now the question becomes, what technical issues might interfere with such a plan?

corrosion or freezing the water.

Corrosion may be an issue but freezing?? Not likely! After all when the ambient air temp goes down that much you don't need water cooling so you drain the system. Once air temps are that low there is enough cooling from air to keep the solar panels at a high efficiency level. The problem only occurs when solar heat raises the panel temp well above the standard temp conditions of around 77F.

Corrosion inhibitors can be added to the circulating water if you choose to use a material that does not have good corrosion resistant properties. However I am not sure how much corrrosion would occur at room temp or slightly above.

Aluminum has excellent heat conduction properties so it is likely that aluminum heat sinks form the back panel or mounting frame. That in turn may require using a closed system instead of running potable water through the cooler. If the idea is to pre-heat wash water, again it makes sense to isolate the two loops. I can't see this system approach being practical for use during winter for house heating.

What about at night in the winter? Surely it gets cold enough then? But adding anti freeze is quite a simple trick, a good one also stops corrosion too....

Apart from the steep cost of anti freeze, there is the toxic aspect. At least around here its a major flap if ethelyne glycol is spilled in any quantity greater than one pint. Not only do you have to file a report with the environmental people you are subject to a stiff fine. Non toxic antifreeze is twice as expensive as ethylene glycol.

The greater portion of BC watershed is a salmon spawning habitat. And the protection extends to the ground water table. As such it has protected status and polluters incur the wrath of officialdom. Not to mention the censure of your neighbours. As a result, even hydronic heated houses use straight water and take measures to maintain heat input at all cost. This can involve having an auxilliary heating source that does not require utility power electric pumping, or a backup inverter system to run the AC powered circulation pump on wood fired boilers. Stil cheaper than having to deal with officials in the event of a spill.

Likewise in the rest of Canada. An ethylene glycol spill will get the geophysicists and hydrologists out in droves..........all eventually paid for by the offending party.

but freezing?? Not likely! After all when the ambient air temp goes down that much you don't need water cooling so you drain the system.

Why to drain. It will heat the water and avoid freezing and you get little warm water.

Because ice expands so rapidly as it freezes, the chance of damage is great. Even if the sun heats the frozen water in the solar panel there is also the pipes leading to and from panel. This may not thaw fast enough and thus remain a blockage.

What little warm water might result is not enough to be of any use. And if it gets cold enough to freeze at night, the heating system is already in use. This will provide much more hot water than the cooling system of a PV cell array.

Howdy,

Just my two cents, I maybe up to three by now, but; the issue with liquid cooling solar panels is a good one. For every one degree Centigrade in rise the PV efficiency drops by 4/10 of one percent. That is why most panels are elevated 3-6 inches from the rooftop.

The main concern is when you have a liquid and an electrical source together, there is always the potential for someone to get shocked or WORSE. If we were to use WASTED HEAT. we could use, transformers in a commercial building or the wasted heat energy in lighting. The problem is most North American PV systems require a DC GFCI for ground fault protection. Any "transient voltage will trip the GFCI and POOF no power. If you need more detail, e-mail me and I could go in to more boring detail.

Have a great week

The problem that you run into is when you have a moving liquid in a tube or ???,you also create a static electrical charge. The charge can be very minute, in the milli range. But you still have to discharge this.

The main concern is when you have a liquid and an electrical source together, there is always the potential for someone to get shocked or WORSE.

REPLY: How would this be any worse than rainwater all over the roof after a storm? The same rules that require a DC GFCI also require disconnect points or switches or fuses. If the DC GFCI is placed close to the array would it not also trip if coolant water leaked into a place with energized conductors? And this argument also assumes that a coolant leak would automatically enter into a seperately sealed electrical enclosure that by definition must be weatherproof ( water proof?) I thought that the metal framework of a solar array had to be grounded as part of the lightning protection. Yes flowing liquids do create static; but not much at the low flow volumes required here. If it did, we we would have a huge problem with hydronic heating systems used in thousands of houses.

You are right. GA. The panels have to be made water resistant. This should not be a problem. I produce water cooled power electric converters running with 800VDC and standard fresh water. If we can do it, PV can do it too.

The only problem is that to improve PV efficiency, the temperature rise of the water has to be kept low. This makes it a bad pre-heater if it is a good PV cooler. A heat-pump could be used to concentrate the heat to make it useful and to cool down the cooling liquid. It is more complex but would produce useful temperature ranges.

"For every one degree Centigrade in rise the PV efficiency drops by 4/10 of one percent."

Where did you get this information?

I think you may have to take into consideration the amount of electric energy required to run your circulating pump. That may offset any gain in PV output.

Yes and solar trackers also take away maybe 5% from total energy produces so people leave the panels fixed and lose 20%.

Almost any decent and practical solar panel array will consist of at least a kilowatt of (rated) power and most home installations I have seen amount to much more. Circulation pumps we use in hydronic heating systems consume around 150 - 300 watts depending on size. These pumps are way bigger than anything needed for just the solar panels. My guess is such a coolant pump would be closer to a 100 watt consumption. I was told by a tech at a solar controller company that sun heated panels may lose as much as 50% of their rated output compared to the standard output value. So a 100 watt penalty seems like a good trade off to recoup most of a 50% loss on a 1-2 kilowatt array. And this would only be needed when sun heating went above a certain value. The pump could be controlled by a thermo disk set into the exit coolant flow. Once that drops below a set point the pump stops. By experiment and examination the hottest location on the aray could easily be determined and a "start pump" thermo disk could be installed there. A more sophisticated single point sensor / controller could also be created.

Elnav,

Down here is OZ, there are systems called "SolarHart" hot water systems.

These use convection (i.e. No Pump) to heat the water in an insulated tank at the top of the panels, the hot water is then stored and used for the house.

Now if the PV cells were mounted on the collection panel, the additional cooling improves the performance of the PV and the conversion improved the performance of the H\W system.

Hmmm, Very Interesting...Specially since I'm already looking at Solar H\W to replace the gas system and still want room for the PV.

Good Concept...

Thanks Elnav

Sapper, methinks there might be a fly in your ointment.

The PV panels are supposedly going to see a 30 degree or so rise above ambient. Solar heat panels on the other had often develop much greater differentials near scalding temperatures which I suspect may well be much more than the solar panels can deliver.

However, if the differential is 50C above ambient, then maybe it will be sufficient. Especially down in OZ wher I think your ambients are higher than here in much of N America. I think it would be worthwhile to do an experiment with one panel to see how much heat you can pick up while maintaining voltaic output above an uncooled panel. That would require close monitoring of both voltage and temperatures simultaneously.

50% reduction in output? WOW! I didn't know that. In that regard it would seem that cooling is definately in order. I suppose it may vary with manufacturer, age, material? I will have to educate myself further.

Your reference to solar trackers is a no-brainer. I've often wondered why more installations do not employ tracking. On residential installations I can see where it might not be feasible due to space restrictions, but I have seen several very large arrays (upwards of 1MW) that are fixed and collect incident light for about an hour a year (rhetorical exageration). It seems that if one were to invest in such a large system, tracking would certainly be a "given".

I use calcium chloride to cool an array of eight panels. The panels are 16 yrs old and have gone 11 years past their useable specs with a drop of only 10% generating capacity.

Compared to my neighbour who installed the identical panels (military surplus) without cooling mine have outlasted his by nine years. He is now on the grid.

It's a damn good idea.

Could you elaborate on how you use calcium chloride to cool an array? I am only familiar with its use as road dust control.

The point was brought up that mixing water and electricity is not good. - Correct! same goes for electronics; yet the latest generation of computers have water cooled CPU to control the heat of super fast clocking. I'm told fluids other than water are now being tried. Perhaps this is also suitable for solar arrays. Mind you, the volumes involved are very different. A computer CPU might use a couple of ounces whereas a solar array will use many gallons, perhaps even hundred of gallons. There is a cost factor involved. Ethylene glycol? That can get extremely expensive. And the green variety (old style) is toxic. the newer type is not considered toxic but cost more.

I know the manufacturer of some electrical power equipment I sometimes specify, recently began to use liquid cooling but this liquid is a dielectric oil. The power components are immersed in the oil. This is much the same as power transformers used by the power utilities. Most of them are oil cooled.

There is a manufactere in the US making hybrid panels: http://www.sundrumsolar.com/

They are new. I have no experince with their product. When I spoke with them in November '07, they were going through UL testing. I don't think they have product available for sale yet.

Thank you!

Its the first product I have seen that attempts to use the heat from PV cells. Now the next step would be to create cooling liquid channels in the substrate backing that the PV cells are mounted on. Sundrum looks like an excellent idae for retrofiting to existing solar panels.

I use 280 gallons. A thermostat shuts the pumps off when the temperature falls below 10'C.

Electrical components have been using water for cooling for years. The first large DC drive I ever worked on was a 400 HP printing press drive that was powered by a 6 phase mercury arc rectifier. The steel rectifier tank had water jackets built in to it to keep it from melting. Water and electricity mixed together is just another aspect of the system that needs to be managed.

Not only that N of 60, but large radio transmitter finals, running high plate voltages, were and I suppose still are water cooled.

But Elnav raises an interesting point.

Both my brother and I are printers, mostly retired but still interested in technology.

As most of you probably know there are folks now beginning to print photo voltaic materials on thin films. I had raised and kicked around the idea of using such material. Indeed I had proposed buying a pile of Fresnel lenses as a means of increasing the sun intensity on those films. As you all know those films don't take to heat very well before they begin to buckle, distort, and otherwise become unusable. Those lenses would be sure to raise temperatures, sort of like starting a fire with a magnifying glass.

I had begun to think about water cooling. It really is not a problem. Outdoor electrical systems are usually assembled in and with weatherproof fittings. I have been, as well as a printer an electrician.

Good liquid systems, especially when the cost of the liquid is a factor, are also well secured against leaks. As a pipe fitter (I get bored easy) I have helped install dry fire protection systems, dry when subject to possibly freezing temperatures.

In order to have back pressure on the fire valve the systems are kept under air pressure. True, there is a small compressor attached to ensure air pressure stays up. The truth of the matter is that those systems don't leak and the pump is there in case. If they do leak they trip an alarm just as does a wet system when there is water flow. Nobody wants to be continually running after a system that leaks. They don't leak.

My point is it is possible, indeed done every day, to put together liquid systems that don't leak.

It is interesting to hear I am not the only nut that thought of water cooling solar panel systems.

j.

What type of printing Jack? I worked 6 years in a 4 colour roto-gravure shop. We had four 8 unit Goss production presses and one 4 unit Goss proofing press. Two of the presses could be tied together to form one 16 unit press. We could make a 96 page magazine at 85,000 an hour. We did alot of Canadian and American newspaper color inserts. Did Today magazine for Long Island NY from about 74 though 82. I did my apprenticeship there. There is something about a big press like that...

In my case mostly photo lithography although I have had some training, London College of Printing, on newspaper presses.

I have also done prep work in a plant running color newspaper inserts. One of our specialties was false comic book process color, I guess they called it false because the tonal gradations were achieved by cutting masks for one or another screen value for various colors thus giving the illusion that the tonal gradations were true color process variations that would be the result of shooting separations from a full color print.

That shop used to run large Harris presses.

My brother, for many years worked for a company that produced phone directories, after market auto parts catalogs, etc.

Now he does mainly consulting and periodically, on the part of a customer over-sees a production run of huge numbers of tickets, part of the image being added on the run by ink jets driven by computers so as to make different parts of the run pertinent to different end users.

Years ago I worked for a while at the Oxford University Press in Oxford.

There I had the opportunity to watch one of the very last artisans of Collotype printing at work. Compared to us press operators that was surely a skill where the term "artisan" was appropriate.

As far as I know, and between my brother and I, there may be little about printing technology that we don't know.

Rotogravure is interesting. Just a short while ago I took a course in print making at GSU here in Atlanta. Gravure there was the design and etching of plates and printing on what you might refer to as a flat bed proof press; ink rolled on by hand, wiped by hand with a blade, set on the press bed with a sheet of paper on top, and then printed with pressure from the roller.

At GSU I also prepared and imaged, by hand, litho-stone, and pulled image from that. Sort of interesting when you consider the lack of stability of that process, in that the stone chemistry becomes part and parcel of the imaging chemistry as opposed to what, even 40 years ago, was the relatively stable printing environment of metal plates on a photo offset press.

I hasten to add that in England when I was there they were first making the transition to offset. That was hardly stable and in order to function there I really had to learn the underlying chemistry of litho services because nice things like the 3M "R" plate were not generally available and when it became available under license, they were producing the plates in a plant that was not air conditioned and hence, with a constantly changing emulsion viscosity, were not producing plates of uniform sensitivity and characteristics.

At that time they were involved in a major economic downturn and although they had hired me because of my U.S. technical knowledge were not willing to pay for the tools necessary to enabling process stability.

Those big Goss presses. I imagine they were four and four with the webs coming together in the center between the presses and there entering folding and finishing machinery?

In New York I imagine you were a member of what in my day I knew as Local 1 of the Lithographers Union. Three of us became members of that union when we organized the little job shop (Four presses, two 17x22 ATF's, a 29" ATF, and a Multi and a prep department) we worked in on 22nd Street. That is where I first learned about offset and prep reading the Lithographic Technical Foundations The Lithographers Manual, a Seventh Edition of which I still have here today. When in London I needed the chemistry for fountain solution I finally found their technical pamphlets at the London College of Printing.

At any rate, to bring this back around to the opening issue, Solar Panels, it appears that as printers we might be able to make our own providing we can ascertain the chemistry of the appropriate printing inks. From there whatever process, letterpress, letterpress with Dycril plates or running on litho presses as dry offset, flexo, whatever, it is no biggie.

j.

Use it mixed with water.

The reason I use CC is because of my homes' proximity to a lake and in the event of a spill the environmental damage is virtually nil.

It does freeze at -30'C.

What percentage or concentration of CC solution. From my experience with CC while living in Ontario this stuff is very corrosive. What precautions or corrosion preventative measures do you use. As I recall, both aluminum and steel is corroded by CC. If you use non corrosive plastic, how do you ensure efficient transfer of heat to the CC solution. Your proximity to a lake suggest you cannot use much in the way of corrosion inhibitors in the liquid itself.

Corrosion was a serious problem.

I used liquid rubber spun very thinly in stainless tubing at first. I then did the same to straight copper tubing with good results. The joints are rubber and neoprene. The cooling effect is not optimal but it is good enough.

Last year I used an elastic varnish made by Epifanes...the jury is still out on that one.

As to concentration I played it by trial and error. Using CC on my photovoltaics was also to do with keeping bacterial growth at a minimum while not using ethylene glycol.

Ok now you really have me intrigued. How was the rubber spun into the tubes? If your tubes become the principal heat collectors, how do you transfer heat from the PV substrate to the pipes. Evidently these are removable since you changed from stainless steel to copper.

<VBG> that stainless didn't by chance come from Douglas Point - did it?

Not Douglas Point (is that the stuff that was radioactive and sold as surplus?).....my stainless came from a kitchen that fed a military base. It was surplus.

Spinning liquid rubber into the tubes is very easy once you determine the rpm needed to get a proper thickness....I built a small electrically driven chucking device with a modified live centre at the other end....poured in some liquid rubber into the tube, mounted it into the gizmo and fired it up until the rubber became stiff. 20 rpm for 3-4 minutes usually did the trick and the result was a fairly even interior thickness.

Obviously since you are doing it, it can be done, and if nothing else has the implied benefit of extending the life of the system. I read what was on the thread and started to wonder if ethelyine glycol was the same glycol we sprayed on aircraft wings in the winter to retard or melt ice.

Hi Transcendian

Yep.......and they still spray it though nowadays the spill is contained. Many of our abandoned bases are so contaminated that nothing can be built there for people.

My original plan was to use ethylene glycol but I thought better of it. I don't know how long the photovoltaics will last but so far so good. Easier to go on the grid....and cheaper. I'm forever replacing batteries and they are not cheap.

I was thinking about using product that people use to heat swimming pools.

This is a rubber or plastic type product which has tubes running water through absorbtion pad.

This could be fixed to back of panels and and flow pipes connected to manifolds that feed cold water to top of panel and take away hot at the bottom back to a heat exchanger, ie. car radiator in drum of water.

I had also thought of closing off top and sides of panels and fit a chimney on the top section to make a continous draft under the panels this way taking heat away at no cost to watts produced.

how do you apply calcium chloride and does it keep them clean? thanks

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Make a big CPU liquid cooling block out of alum or copper same size as solar panel. Attach it to back of panel with thermo-epoxy which have good thermo-conductivity. The passage in the block should allow total drainage by gravity. Connect the cooling block between water inlet and hot water tank. You don't need a pump. If toilet water is from same source, you can route it there also to get more water flow.

Another way to do it is use air. Air got heat up in block get out from the top. System can be open in summer and route to preheat air in house in winter.

Can we pull solar panel inside a box with glass? Like a solar air heater. Air inside the box will get heat up and we can use it to preheat house and cool down panel. Question will the extra sheet of glass reduce panel efficiency?

Would almost certainly reduce efficiency, but I'm not sure by how much. Anyone have data better than a SWAG?

Question will the extra sheet of glass reduce panel efficiency?

Yes...the secondary albido will reflect a lot of the light away from the panel.

Attaching with thermo epoxy is permanent. Good idea unless you need to take it off.

There are heat transfer paste and tape but they'll be more expensive and you'll need a lot of them.

Is there High E glass/lexan that'll allow more light into the box?

Mine are polycarbonate which I have to polish every couple of years. The ones made from glass had a tendency to become pitted so I did replace with (lexan) polycarbonate.

I might be wrong I don't think allowing more light will actually increase the generating capacity. I've read some used fresnel lenses to concentrate the light but I imagine that this would burn the array.

The question I would ask is whether these pastes and tape could withstand being outdoors. If there was an epoxy type (add iron filings maybe) with a release agent ........hmmmm......now you've got me thinking...........

Duckinthepond have you tried DEVCON epoxy. It is metal filled and as such has better heat conducting properties. We often use it to repair small machinery parts. I have used both aluminum and steel filled DEVCON.

Yes...I've got these epoxies. I can't apply to my collectors in the event I'd need to disassemble them.

A product I do use a lot of is made in Edmonton...called Endura.......it's a rayon matrix as opposed to a polysterene one. Very tough stuff and can be used as a permanent topcoat for decks. Not cheap.

There is a thermal paste ( removable ) used in electronic assemblies to join transistors and heat sinks. I do not know for certain what the composition is but have heard reference made to zinc oxide in connection with heat conduction paste. If zinc oxide is in fact what is being used, then the extreme sunscreen paste may in fact be a close cousin or even the same substance. Does anyone know more details?

A company called Paratherm makes a line of heat transfer fluids, several of which are FDA approved for food contact and should therefore not be a pollution hazard.

Aren't we getting away from the main point. Cooling by liquids is only required when its HOT! Which means summer and thus why worry about freezing. As seasonal changes brings down the ambient temperature, there is no longer a need for cooling the panels as much. By the time you reach low temperatures that could freeze water you don't need massive cooling by any transfer liquid. So drain the water. No ecological damage. No pollution.

Now about the calcium chloride solution used for cooling. Does this solution have better heat transfer characteristics than plain water? If so, by how much?

Elnav my friend, not everyone lives in the cold frozen wasteland of the north such as yourself. Some of us live in the third or fourth circle of hell. In Houston Texas it is not at all unheard of for it to be 80 degrees F on Christmas Day. The High Temp today was 96 degrees F. Last week we had a couple days where it broke 100. And of course since we are closer to the equator, fixed PV panels are far more efficient for us too.

Yes, but why would you then need anti freeze in Houston? Why would not plain water cooling work?

IBM was cooling their mainframes with water back in the 70's.

The use of calcium chloride solution to move heat is an old technology. Calcium chloride solution is passed over refrigerated coils and then circulated through pipes buried in the concrete bases of commercial hockey, curling, and skating rinks to freeze the water that is sprayed over the concrete. Calcium chloride solution freezes at a temperature much lower than that of plain water. You could use a calcium chloride solution to remove the heat from the back of your PV cells, it is certainly a less noxious alternative to convention anti-freeze and I expect that it is probably less costly as well.

I do not know how the freezing point of a CaCl₂ solution varies with the concentration of CaCl₂ in the solution, I am sure that someone in the group does though.

For about two weeks or so in the "winter" we do usually get down into the 20's and sometimes into the high teens at night. But that is not really the reason for that, since you can always drain the system when that happens. The issue here will be heat. How to keep the water from boiling. I think the solution would be using a closed loop of heat transfer oil. There is a company down in Oz that makes a really efficient Stirling cycle DC genset (whisper tech) that might be a good use for that excess heat to keep the battery bank topped off. The waste heat could then be used to heat domestic water.

A subsidiary of Boeing has developed a multilayer PV cell that is about 42% efficient. combine that with some advanced heat recovery and you should be able to get some really efficient distributed power generation. The trick will be getting the costs down.

Whispertech has regrouped after some technical difficulties. They replied to my query tha t they wil not sel l their product outside NZ until further testing has been completed in a year or two. At one point I was going to become a trained Whispertech installer in the PNW region.

As an aside the heat differential involved with water cooled PV installs is too low to be effective. Stirling engines typically work better with temps in the range of a flame. Look at the California test facility done with PG&E This is a multi -megawatt facility using direct solar heat focussd using parabolic mirrors. The heat developed at the heat receptor of each stirling engine is several hundred of degrees. Somewhere the numbes 700 C keeps coming to mind. No transfer fluids. The solar heat is concentrated directly onto the heat receptor of the Stirling engine

I was unaware of their difficulties. I was aware of a testing program they had entered into with BP to supply power to remote pumpjack (oil well pumps) installations in Wyoming burning wellhead gas (NG). They were in the 3kw range if memory serves which was none too shabby. Word I had received was that it was mostly successful.

I think Houston in the summer could attain temps approaching the ideal for a Stirling. But maybe not so much the rest of the year. But I bet we could figure out a way of switching to NG combustion for the rest of the year. Other parts of the country might need to look elsewhere.

So what are some other things to do with the heat generated?

Thermoelectrics maybe? Vaporizing a low boiling point liquid (alchohol?) and spinning a micro-turbine with it? storing the heat in an insulated salt pit for load balancing at night?

maybe an ammonia/water absorption chiller to boost air conditioning efficiency? That would be a big seller down here I'd bet. Natural Gas or electricity could be used as the heat source at night.

The difficulties centered around not being able to find a reliable supplier of precision machined parts made to very close tolerances

The consumer version sold through Victron in Holland had bearing problesm and reliability issues leading to excessive warranty calls.

I have been looking for a source of Stirling engines made in North America. Not much luck except for hobby and science faitrtype demos. So far i hav eonly found one manufacturer but its Swiss made and not ready for UL certification and export. Th product is really neat. Mounted on top of a pellet stove it makes electricity from wood heat and the wood heat is used for house heating and hot water. Output capacity is around 2 kilowatt fed to a storage battery. Normal inverters can then deliver household current. In this area where many people heat with scrap wood from beetle kill, this would be ideal. The company told me to wait for a year or so before looking at doing any sort of import to North America. And no they don't have a website.

As for what to do with low level waste heat. By low level I mean less than boiling point at atmospheric pressure.

Domestic hot water probably doesn't use enough. I doubt Houston cools off enough at night to need house heat. A heat pump of some kind might make sense if the higher resultant heat could then be put to work. Baird industries in LA makes potable water from salt by using waste heat from engine coolant and exhaust. But they use a vacuum pump for evaporation. Its doubtful if this makes sense in a PV house installation.

I think you are right some kind of ammonia cycle cooler like the RV fridges might be the best. Depending on cost for fuel this may even make sense to shift away from electric loading for air conditioning.

yep, I'm looking at these guys:

http://www.gasairconditioning.org/residential.htm

<...need anti freeze in Houston...>

Some resilience against uncontrolled biological activity in the system is usually a good idea...

Just curious - how does bacteria get into a closed system using sterile water to begin with? Hereabouts we can leave bottled water sitting in the sun for six months and it doesn't show any bacterial growth whatsoever. I suppose if you use a contaminated source for water that might be different.

I doubt that the tubing and fittings have been sterilized. I'd bet the farm that they have all kinds of bacteria growing on and in them.

hope you don't need that farm for a home. Think about it for a bit. In summer time the solar heat will bring the temps up past the pasturizing temperature. So if there was any bacteria present the heat would kill it. As I said before, we have pretty clean water here. I have left bottles of water sitting in the sun for up to six months without it showing any growths at all. It was an experiment to test for growth by any organism present in the water. Somebody said water goes bad after a month or so. Not so by my experience. Many northern locations are drawing from aquafiers that stored water dating back from the last ice age. Even when water percolates through the ground, much of the water can be seveal thousand years old. This last number comes from hydrologist whose job it is to study such things and ascertain the safety of public water supplies. Deep aquifiers are safe, its only shallow surface water sources that pose a risk. I guess we are spoilt up here.

Drinking water is very geophysically specific.

I have two wells. One is shallow (30m) and the water is very young. This water is low on certain minerals content and is excellent for drinking. The second is (150m) deep and highly mineralized. When the second was drilled it went through a vein of arsenopyrite and became contaminated two years later. It also had high concentrations of mercury which is found in certain geological formations.

I cannot stress enough the safety element involved here. It is well worth the price ($1000) to have ones' drinking water analyzed for mineral and chemical toxins.

The system must have some kind of breather port to compensate for thermal expansion does it not? Would it not suck atmospheric air (or fresh, unsterile water, depending on the design) into the system recontaminating it each day?

No! Thermal expansion is accomodated by having an expansion tank. In any case charcoal or simiilar particulate filters would block insect ingress and also minimize any bacterial contamination. With proper sysem design the amount of "pumping" from expansion / contration wouldl be minimal. Its not as much as you get in a car's radiator sytem. It sounds more like speculation on your part than actual experience in our local conditions.

Furthermore, for the sake of keeping the water pure and mineral free, I would prefer using distilled or RO water either of which is available locally for $2 per five gallons (imperial). Our own well has a high iron content in the winter so we wash with it, but get RO water for drinking. However a friend nearby has a well with clean, pure water. Because he runs a summer camp, he gets the water tested every month. Its certified safe and pure. $1000 for testing? You gotta be kidding! It cost $10 per sample in this area if you take it to the public health office.

The $10 test you are referring to is for bacterial contamination. You can do that at home with a microscope.

The one I'm refferring to is the one a hydrologist would do. There is a test kit provided by a company called Maxam. It tests for mineral and chemical contamination.

You might be interested to know that drinking distilled water will de-mineralize your body. There was a hard lesson learned by a group of naturopaths who promoted such use in Ontario. The idiot media picked up on it as something 'pure' and 'good'. Many elderly people became very ill. The naturopaths were taken to task for promoting such use that they eventually lost their right to practice homeopathy. A public health alert was issued advising people who drank distilled water to see their doctor asap.

"cold frozen wasteland of the north" - you gotta be kidding! I was doign a show this week-end and the solar panel we had on display at the booth got so hot you could not place your hand on the frame, let alone directly on the front of the panel. It was 160F. Ambient temps reached 95F. At this latitude we get roughly 16 hours of sunlight per day.

Good link...thanks. Have spoken with their techs and am about to go to plan B re cooling.

Is there any news on this issue, Elnav?

At this moment i am busy to investigate this issue for a solar boat.

JPD

the netherlands

The energy research centre inthe netherlands has come up with the awnser, and spin off company "pvtwins" produces these hybrids. corrosion and or freezing can be overcome using thermal oil and a heat exchanger.

here in Sicily the cooling must improve the electrical effiency but what do i do with all that hot or ( even better) warm water?

i thought of superheating (solarboiler) it and with the steam, create more electricity.

but as most off us lack sufficient funds to build test rig.

john ( give me funds, i'll come up with a project)

I just saw such a system on the TV show Renovation Nation on the Green channel. The guy had what looked to be standard 2x4 ft. solar photovoltaic panels with a water cooled tubing and panel on the back.

He was increasing the output of the Solar Electric side and also heating water for the hot water system or you could put it into a larger tank for radiant home heat.

But he was saying it would be on the market "soon" . It was on the show with Steve Thomas. Its on Planet Green channel

Have been thinking the same thing for years. Recent Solar Exhibit in San Diego convention center had "reportedly" only ONE both that was exhibiting a ??? Missed it myself. Some of the problems are. Building codes are very negative with regard to water and electricity being in the same place at the same time.. It is my understanding that the physics idea is correct from what I have seen in spec sheets, but I have not been able to demostrate in a simple experiment of cooling some solar panels with water to see if the Voltage or Amperage goes up. Please let me know if you find any panels that I could test. Would want a cooled and non cooled version of the same panel. cb Chris Bickford La Jolla CA

Check out sundrum.com they have a commercial version of what you are describing and I will be calling them soon. Don't expect an answer on the Sat weekend, but the tele # is 5087406256

Seems like this came up before. Seems like I remember that one of our contributors had developed a cooling system using Calcium Chloride in a slurry to cool in a loop system.

Possibly you might try the Search all of CR4 box with the phrase Cooling of Solar Panels to rediscover what I partially have forgotten, though at the time thought of value to know of.

I can't believe that no one has tried what I have done, and it is so simple and effective.

I use an oscillating sprinkler to spray my panels, set from a 20/20 cycle on/off timer. The water comes from a rainwater tank attached to the house roof, and a 400w pump runs the sprinkler at 2mins on, 13mins off, during full sun days, even on mild winter days here in Sydney. About 60% of the water returns to the tank.

On days when it is 40ºc (104ºf) ambient temp', the panels can be at 70ºc (158f) without cooling, and the sprinkler can keep the panels at the ambient temp'. In this case improving output by around 12%.

No need for fancy backing plates etc, simple as..