Solar Panels in Winter

If I was going to do this, I would consider using common household ammonia.

Water its cheap ,easily obtainable and suitable for experimenting with.

Sounds like you are trying to make a heat pump. R-134a or R-12 Refrigerant

Old auto AC change the direction of flow.

Water is no good 'cos I can't get upto 100deg C in winter.

Dunno where to get refrigerant...I'll have a shufti on the web, but I was sort of hoping for a household/common/easilly obtainable chemical. The only volatile stuff I can think of is rather flamable.

Del

An actuated parabolic dish reflector with a central column containing saltwater maybe

Maybe I'll ask customer services as Sainbury's .

First frost this morning....

Del

is this a closed system or a open system?

closed systems have utilize a heat exchanger to transfer heat energy your water, transferring it from an agent such as ethel glycol.

I would opt for a solar reflector in this situation. It would certainly make your summer showers a bit steamier.

The current system (see the link) is open, but the mkII winter solar system could be anything, I'm looking for something which I can build myself which will give improved performance for winter when the sun is lower.

Del

I wanna pass you a pdf file for you to look at, how can I do it?

Dunno..
Can you link to it? or cat cut and paste it into a post.
Or attach it as a file and Email it to my E-mail addr (which I can PM to you if you want).
Just slide it casually to me when no one's looking? put it on my desk?

Ask admin...
Or post a question on CR4 asking how

Del

Del what is your email or have you received it already? I sent it to your website.

Can anyone tell how can i attach pdf files here? I don't know the site where I got them off.

Water at reduced pressure in a sealed tube has been used as a heat pipe. My solar heater uses this system.

A reflector would seem a good idea as it can increase your solar heat collection area.

I can't speak much from direct experience as here (Northern Australia) we never get frost and summer (our wet season) is sufficiently cloudy that solar heating is reduced. The best time for my solar water heater is mid winter!

There must be a fridge collection centre near where you live. They have to drain the refridgerant before the fridge can be scrapped and probably have gallons of the stuff to give away - ask Comet or Currys where they take their returned freezers.

We used Freon to provide heat/cooling for the camera in a TV guided missile manufactured by HSD at Hatfield so they might know of a supplier in your area.

The council tip scrap fridges, but I don't spose the give me any juice...
'more than my jobs worth' I expect, I'll have an ask next time I'm there, although one is usually met with blank incomprehension.

Lat time I went there with a big tub which had some adhesive left in it, there were all sorts of special disposal instructions... I asked the bloke at the tip where the chemical disposal section was. He just took it and threw it in the general rubbish!
Maybe I'll spot an old fridge at the roadside

Del

Yup, see post #20 I got 'em when you E'mailed me, and the link works too

This link is a similar system to mine. The heat pipes use water at low pressure.

Was yours DIY? Can you post pics?

Wouldn't be much good over here with water, but could be OK with different fluids.

No, mine was bought. Making double wall vacuum insulated glass tubes with copper heat pipe is a little beyond my capabilities - except of course in my dreams.

Though corrosive I used calcium chloride for many years. Can be bought where farm tractor tires are filled with same and is environmentally safe. Works up to -40'C.

Thanks to the advice of a CR4'er I'm switching to propylene glycol this year....biodegradable and non toxic.

CO2 gas is almost free and used now as an heat exchange gas.

Del

you are looking for "solar heat pipe tubes" ; google that and look it up on alibaba.com

i will try to post some links for you tonite as i have been looking at these for a while

http://www.benchtest.com/heat_pipe1.html

i think also that acetone (flammable!) and other low boiling point liquids are used

http://www.siliconsolar.com/ in the USA sells this stuff for reference

One alternative we have kicked around is to get a group together and buy a container factory direct from China -- this is half price of the retail listed on most web sites and if you organize the activity you might get yours for free? ;-)

this site has very interesting general information

http://www.ren21.net/

please keep us updated as you proceed - it is getting cold in Michigan too by the way!

That first link is great, I just had a skim I shall study it tonight.
Cheers
Del

You want HIGH temp? here's what you should do...

Get yourself a large lens, install it in the center of a parabolic dish and in it's focal point install a high temp. glass coil filled with thin clean dark colour high temp. oil, a small circulation pump circulate the oil through a heat exchanger, you can easily make steam if you want. The oil will heat to 600ºC. even on a cold (but sunny) day. You will also need a simple sun tracking device to stay in focus. Easy to home build.

And if all else fails, time to switch to the secondary system, The wind turbine. and if your winter is like ours, than it IS windy...

Are you buying this?..

Wangito

Easy to build is easy to say, but I get the idea.
I'm thinking of making a reflector, I'll probably try and avoid the lens tho'.

Am I buying it?...nope, I'm hoping to make it
Del

I meant buying the idea, If you are like me we don't buy we proudly build. (it's 'cause we're penniless as a church mouse)

Wangito.

"penniless as a church mouse, ahhh? That means you must be a catholic.

There were times when a church mouse was definately the best off amongst them all, are you sure you not the loaded type?

Sure as hell no... (I wish I was...) To make things even worse, I am Jewish

Reminds me of the guy who asked Sammy Davis Jr, "Isn't that enough that you are black, blind in one eye, 5 feet tall and now you are converting to Judaism?..."

Wangito.

I grew up with that expression and as I got older I started using it quite freely myself, until somebody told me 'church mouse can be rich you know!'

As they used to get the magical 10% of everything, guess this is what brought the saying about catholic priests 'preaching water while drinking vino/wine' - myself baptised as catholic.

Whynot just rub up on del panels and then discat into a reverse Tesla gizmo?

Del, the reason I passsed you the details about helios because it must be similar to that hot pipe bench test the guy was talking about to cool his PC's micro.

I just wanted to point out there's some kind of stuff that is an excellent heat conductor but, above all, the vacuum in those glass tubes can help any kind of solar panel become more efficient as it is almost a perfect insulator.

Of course the costs can be quite high and I would use something that is not an overkill but still good in the given enviro to use.

Del,

Both the two options mentioned by you are met by the system that uses concentrated solar collectors and aims this energy on to the evaporator end of a heat pipe which contains water under certain vacuum. Because of the vacuum, the boiling point of water inside the heat pipe is reduced such that a phase change takes place, typically, at 30degC. The heat pipe then transports this latent heat of vaporisation to the other end of heat pipe where this heat is taken away by the water that is to be heated. Because of giving away of its latent heat, the liquid inside the HP condenses and moves to the initial end for a repetetion. 'Heat pipe does not require external energy for operation other than the energy it transfers' and is a passive system.

There are many guys in the market doing this and what you need to do is to just modify your existing system accomodating this technology.

You know winter is fast on us and cats should be indoors moreover, we need you to keep purrrrrrrrrrrrrring !!

Seems to me that the issue is less insolation (solar flux) falling on your panels. Not sure changing to a heat pipe type design will improve "hotenough quick enough" performance.

Increasing area directly By adding more panels or indirectly by adding reflectors are your real options. Better insulation on them might also improve performance.

While youre considering reflective concentrators, what about large fresnel lenses? They should give you a bigger delta T.

milo

Exactly...
It's the increased delta T I need.

If you assume I run the gas water heating for a burst in the morning to get the water hot enough for a morning shower before the sun is up.
This will loose some heat during the day,say down to 50^o (just for a figure) I need a Solar water system which heat the water to a greater than 50 so that it can be transferred. (In the Summer it easily gets above this).

Do the Latent heat tubes get me to a higher temperature? Will the liquid re-condense and transfer the heat at above 50? This is where I don't really understand it.

Maybe I can make a Fresnel style reflector... e.g a parabolic reflector but relatively flat, out of sections of my aluminium clad insulation board, concentrate those feeble rays onto a small section of collector pipe.

Del _{(isn't it about time one of you tight wads gave this thread some stars? [Kris made me say that])}

"Maybe I can make a Fresnel style reflector... "

Guess you could, but it'd take a lot of work. How big is your collecting surface? For the Fresnel thing to be much good, each chunk of your al. clad board would have to be about the same area.

Yup, I was thinking a collector as a strip say 6"x 3' (or the same size in metric)

So the reflector would be similar sized strips in a sort of staggered louvre arrangement..or a sort of quantized parabolic reflector (only parabolic on one axis).

I thought this would be easier to set up than trying to make a parabola (I've seen the various solar reflector and parabola making threads)

Del

That sounds a lot more practical than the kind of circular array I was imagining. Sounds like a goer.

Parabolic requires tracking sun A Hyper geometric reflector flat at top tight curve at bottom, pipe in focus is "self tracking. Perhaps that after the flat panel???

I'm looking for design info .milo

GA

Wow! That first link is amazing! One of those 'Why didn't I think of that?'

The second link doesn't work unless you remove the ? & beyond.

I believe for a Fresnel reflector to be efficient, the strips need to be no wider than the absorber, in which case I think the curved one would actually be easier to make.

The article says 'hyperbolic' reflector. I haven't yet analyzed whether that is a misprint, or whether using hyperbolic instead of parabolic is part of the breakthrough. Just from a quick look, their illustration looks parabolic...

Thanks!

It is Hyperbolic, and thus does n't need active tracking.

A parabolic one will require movement to stay with sun.

We look forward to Dels next report!

milo

Great link....cheers...now I've got too many projects on the go . (that's a good thing)
Del

Hi Del,

Did you miss the post

#28 ?

I thought quite answered your query. Hot oil run into a heat storage unit (salts) @ 500°C may render your morning rain locker experience unique.

Here is a link for a DIY fresnel lens collector, made with a lens salvaged from an old rear projection big-screen TV.

http://www.instructables.com/id/Giant-Fresnel-Lens-Deathray-An-Experiment-in-Opti/

I envision a row of these under a simple glass lean-to on the south side of the house, slightly out-of focus (so as not to achieve copper melting temp) on a horizontal black iron pipe. The mount for the lenses could be designed to pivot around the pipe axis, to allow manual latitudinal(?) focal adjustments every fortnight or so, without worrying about the east-west tracking (perhaps reflective surfaces at both ends inside the lean-to?), as the concentrated rays would still be hitting the pipe in the morning and evening, not perpendicular, but closer to the focal length.

Just a rough idea at this point, but possibly worth pursuing.

Wow that's spectacular...

Try an oil filled glass tube instead of the black pipe. Be very careful using black steel pipe because it can split without signaling...

Agree heat pipe alone will not help. More insolation is needed.

Look into heliostats. An old, out of date computer is quite adequate to control the pointing of the heliostats. Try http://www.redrok.com/concept.htm

I think programs for the control are available (free) on the net.

An old, out of date computer is quite adequate to control the pointing of the heliostats.

Using a simple equatorial mount simplifies the pointing, and accuracy isn't critical.

How much cloudy weather do you get in winter? The performance of concentrating collectors deteriorates badly when the solar source becomes diffuse, whereas flat plate collectors are only affected by the drop in insolation.

This could force you to stick with flat plates.

I can't really quantify the cloudiness, even if it's overcast 2 days out of 3 I'd be getting some return.

Maybe there isn't an easy DIY solution, but it's good to have a go.

Your comment...
The performance of concentrating collectors deteriorates badly when the solar source becomes diffuse, whereas flat plate collectors are only affected by the drop in insolation.
Is interesting, what do the clouds do? What is the radiation that gives us the heat is it IR UV or what? Does an aluminium reflector work as well on both? Do the clouds absorb the all the good stuff. Got any more info?
If we can come up with some sort of feasible scheme I shall have a go at building it.

Del

Both light and heat contribute. The light is absorbed by the collector and it's energy turned into heat.

I think some 2/3 or more of the energy in sunlight is actually in the infra red, but it doesn't matter as the short IR focuses the same as light and reflects fairly well off most of the common reflective materials, although gold is probably the best for both short and longer IR. Most good absorbers of visible light also absorb IR well.

Concentrating collectors focus the light and heat. Clouds act like a diffuser, so the light is no longer parallel, but coming from all directions and unable to be focused.

This doesn't affect a flat plate collector as it is not focusing anything, just absorbing it.

Clouds also reduce the total insolation just as a diffuser reduces the total light energy available.

According to the guy at Redrock, heliostats are quite cheap and comparatively easy to build and control.

I haven't tried to make one myself mainly because I have a different solar condition here. Winter is warm (Maximums around 25+C all winter) with lots of clear days, so a heliostat arrangement wouldn't help me.

Our summer spends weeks overcast and raining (we get about 2000mm a year, about 3/4 over summer) although temps are around 30C every day. I'd love to get more out of my water heater in summer but, apart from more flat plate collector area, I can't think of a cheap DIY way, so I have to accept off-peak electric supplement.

Any suggestions would be welcome.

I finally looked up your water heater arrangement. Love it.

OK. The good news is I have some free time now. The bad news is I have some ideas for your solar heater. The gas fired water heaters are not a good combination with solar heaters. The venting required to send the exhaust out of the house, also allows cool air to vent through the heater, cooling the water back down. Any system that would block the exhaust venting could be dangerous when the water heater is heating the water. A few years back I sprung for a solar panel water heater on my roof (collector size about 10 ft x 4 ft ). It had a circulator pump that ran off house current, and was switched by water temp differences. It quit pumping after about a year. Contractor was gone. No more pump. The solar assist water heater was new also. It was a large 80 gal size. About a year after the pump quit the water heater tank started to leak. contractor still gone. Manufacturer of the tank says contact the dealer. dealer says show him some certification that it was installed by a liscenced contractor. Screwed again. Hurricane Wilma hit, and the old water heater was still here in it's outdoor shed. Wilma moved it and the shed around the yard, causing lots of damage, so the insurance company paid for a replacement. I was going to get propane powered till I learned how the heat went out the vent all the time. Instead I bought a Relient 85 gallon PLASTIC water heater. Highest efficiency rating on the market here, and a lifetime warrenty. The roof replacement is almost done. Soon I will remount the solat panel bact on the roof and plumb it to the water heater. This time I will use a solar electric panel to power the circulation pump. When the sun shines, it pumps. When the sun does not shine, I don't need to pump. THAT is suggestion #1 for you. In south Florida, the open solar water heater is just fine.

Suggestion #2 is to add more solar area. Here we see undergroung sprinkler systems run with flexible PVC pipe. At the foot of your solar panels, construct some cheap collectors out of flexible PVC. A 4' x 4' flat bok lined with the reflective foil foam insulation. A 1/2" hole in the middle with a 90* elbow. Spiral the PVC around and around till you run out of space, then poke it back out. Cover with lexan sheet and nail it down. They should be buildable for under $30 each.

The running parabolic reflector sounds like a worthwile project. If you have a wood router, it should not be too hard to make the needed profile by shaping two separate halfs of the reflector in longboards, and having the seam below the tubing. Use the paint that gives you the closest thing to chrome you can find. You could run this high efficiency collector along the edge of all your roofing. Sort of like a roof drip edge.

The following suggestiond might need some further refinement.

• Extend the pipes from your collector to your neighbor's water heater.
• Extend the pipes from your collector to a warmer climate.
• Fabricate large bird cages on your roof from black painted copper tubing, and connect to the existing collectors. If you put owl decoys in the cages, it mifgt scare the squirrels away.

Now aren't you glad I found your thread?

Now aren't you glad I found your thread?.

Yup, I like a good chuckle.
Cheers
Del

Hi Del, Please just check this out.. http://www.acrosolarlasers.com/index.html This guy is on top of it. I plan to use some of his tec. on my project which is too much for me alone, but is what we need. www.solarthermalelectric.org There are many road blocks with this project but surely they will be overcome.

The dish is best because there is so little area to insulate. The trough is good because so little tracking is needed.

Amplification of the sun is key I believe. Good luck

Great info solarthermal! Thanks for the links.

milo

Cool links..I'm going to have to do a whole section in 'Favourites' now entitled Solar DIY... (or maybe solar fun stuff )
Del

For interest sake only, check out this solar mega project (you'll have to put up with a short advert first):

http://dsc.discovery.com/video/player.html?playerId=203711706&bclid=958525258

I saw this back around in the mid 80s when, if I recall it correctly, the French or maybe the Germans had one as an experiment.

It was not such a bad idea as long as you have all year round sunshine and better still, if you could do green house vegetation in the enclosure without cooking yourself to death in it.

This experiment was shown at the time by an Australian series called 'Towards to 2000' that later changed its name to 'Beyond 2000'.

Come to think of it I saw this footage before.

It's featured on CR4 before, but I still can't figure out what happened to it all - it seems cloaked in a curious lack of information.

http://en.wikipedia.org/wiki/Solar_updraft_tower

http://www.enviromission.com.au/