LaBelle House: Solar Hot water system
 

Hello all!

I just took a big step towards renewable energy!

I just picked up a 4'x10' solar hot water panel.

I still need to figure out the heat exchanger, pump, valves, and other miscellenia required to make the system work, but now that my "hat is over the fence", I'll have to do them.

This is a "second-hand" panel I got from a guy who has been a solar installer and home-steader for years.

In these photos, the solar panel is under the electric car frame (Citicar) on the trailer.


http://gallery.me.com/benhdvideoguy/...12461377840001

http://gallery.me.com/benhdvideoguy/...12461377740001

http://gallery.me.com/benhdvideoguy/...12461377940001

Nice find Ben! Where are you planning on putting it up on your property?

When I first saw your pictures, I hadn't read your entire post. I thought that you were going to turn the Citicar into a solar collector.

My current plan involves ground-mounting the 4x10 solar collector in front of the SE corner of my house.

This will ensure that I don't have to put any holes through my roof, don't have to lift the panel up there, and if I want to "show off" the panel, it's on the ground for easy viewing.

I will run the panel pipes to a heat exchanger connected to a solar storage tank. Likely, that will be a modified electric hot water heater. I have an old one I found on the curb to experiment with, but it has a lot of hard-water mineral buildup on the bottom of it.

http://farm3.static.flickr.com/2581/...006fc20e3f.jpg

In theory, the water in the modified electric water heater should thermo-siphon through the heat exchanger. Anti-freeze in the "closed-loop" of the solar panel will need to be pumped through.

It seems that the simplest way to run a pump is to use a DC pump connected to a PV panel. When the sun is shining on the hot water panel, it also shines on the PV panel, and the pump runs, moving the heated anti-freeze from the solar panel to the heat exchanger.

I have heard good things about the "El-Sid" DC pump for use with solar setups.

Of course, I still need to figure out all of my shut-offs, valves, and other connections that have to go on the whole system. AND make it all fit in a small utility room that already has my laundry, pantry, furnace, pressure tank, water softener, etc.

I'd suggest trying out the swiftech mcp350 as your DC pump. Gary at builtisolar has been using one for a while now and has been very pleased with its performance. Plus, its cheap at only $55. Newegg.com has them, I'm sure you can buy them elsewhere too.

I've also started a project to make a DIY thermal differential controller as a cheap solution for the $130+ commercial units. Mine should cost less than half of that. Not absolutely necessary for a PV driven pump design, but it does make the setup more efficient.

Hey Tim,

Thanks for the link on that computer pump.
According to the specs, it pumps on the low end of what I would be looking for volume. Which isn't too bad, because a lower speed improves heat exchanger efficiency.

My only concern is that PVC and plastics like that pump are only rated for 140 degrees F. I don't know yet what to expect for temperatures coming out of my solar panel. On the other hand, at only $55, I could screw up once without it costing a fortune.

I think I will do a test run of the solar panel, heat exchanger, and electric water heater tank in my back yard running off my 12V stainless steel bilge pump. I'll put a thermometer on there and see what kind of temperatures we are talking about.

I do love that the computer pump is low wattage enough that I could run it off of a single 15 watt PV panel. Also, it will run on as low as 9 volts, so I think that makes it into a variable speed pump, depending on how much sunlight hits the PV panel.