DIY solar panels

[Dave Turpin]

I have been reading a lot about DIY solar panels. Seems pretty simple. You buy hundreds of the individual 6x6 or 3x6 panels, and with some fairly labor-intense soldering and wiring, you have solar panels for a fraction of the price of a ready-made unit.

It looks like I could build about 2kw peak worth of PV's for $1000, so it seems like a worthwhile experiment. However, I am also interested in solar heating, and have been playing around with the idea of flat plate collectors as well.

Now, here's what I'm wondering. It seems that PV cells are about 16% efficient. What happens to the other 84% of the solar energy? Is it waste heat inside the cell that then has to be drawn off? If so, what would be the possibilities of building a hybrid PV cell / flat plate collector? Basically my idea is 48" x 96" panels, each which would contain 128 6x6 cells wired in 2 strings of 64 series cells. (Overall outer dimensions 50x100") each with an enphase inverter or possibly just a central PV inverter to make AC power. Behind these flimsy panels, then, I would use a thermally conductive but electrically insulating material further backed by an aluminum or copper sheet with serpentine copper piping crimped into corrugations. The pipe would form the flat plate collector. These whole units then would be boxed and laminated with an air gap and solar glass.

So the obvious question would be: Would this affect the heat collection so much that it would be better to have seperate collectors from the PV's? (limited roof space on the house I am thinking of) And... Would the heat removal positively or negatively affect the performance of the PV's?

Thanks!

[Rob Beckers]

Hi Dave,

With PV prices approaching the $2 mark for the lesser-known brands (that still give you 25-year warranty) I'm not sure making your own panels is worth it. Those nearly-no-name panels will be far better in quality than you can do on your own (unless you have a robot assembly line in your garden shed). Yeah, your numbers say you can cut 50% off that price, but keep in mind that you'll very likely have panel failures that will cost money. I don't think you'll get a 100% success rate for DIY panels, especially if this is something you've not done before.

Attempts have been made to combine hot water with PV. In fact, it's still ongoing (forget the brand name, but there's at least one manufacturer flogging this product). Trouble is that despite the superficial similarities, both actually need opposite environments to function well. PV modules need to be kept cool for best results, while solar hot water needs to come out, well, hot. I can see some utility in using water cooling of PV modules as a 'pre-heater', with 10C water going in, coming out at (maybe) 40C, then going into a proper solar water heater. You'd get away with less surface area for the regular solar water heater for the same BTUs. Expecting PV modules to also heat water to 60C or more will cost you dearly on the PV production side though.

-RoB-

[Angela Smith]

Hi Rob, Your response enlightened me. Thanks for sharing these awesome info's. Harvesting solar energy with the use of a home made solar pane (http://www.solarpoweraustralia.com.au/residential.html)l is becoming more and more practical and popular each day because of the many benefits it delivers. Building your own solar panels is a very good investment for the future, not only in terms of economics but also environmentally.

[Dave Turpin]

Actually, Rob was sort of against DIY panels.

[Rob Beckers]

Not really against them, as much as that doubt their financial sense. Factory made modules are cheap enough that it has become hard to justify DIY, other than for fun and entertainment.

-RoB-

[Russ Bailey]

I am a moderator on a solar site - Judging from posts there, I really think that people have a great deal of difficulty building a panel that will last even a few years.

Really difficult to go up against the big factories with all the correct equipment in a competitive market.

Solar thermal panels are a different story. The market is not nearly so competitive it seems. Hard for people to find a good deal. Those are not nearly so hi-tech either. That goes for both air and water heaters.

Russ

[Angela Smith]

Actually, Rob was sort of against DIY panels.

Atleast sharing some good word that was indeed makes a lot of sense. ;)

Considering Solar Energy, yes... it was hard at first. There is a start up cost, but then it starts paying for itself. Once you break even, everything after that is profit. Compare this to paying a monthly bill and getting no return on investment. In the long run, solar electricity is cheaper than buying it from the power company.

[Angela Smith]

Solar thermal panels are a different story. The market is not nearly so competitive it seems. Hard for people to find a good deal. Those are not nearly so hi-tech either. That goes for both air and water heaters.

Russ

Solar energy is not yet a commodity, but more and more people are looking toward this alternative energy. One of the least expensive forms of alternative energy is solar-thermal (http://www.solarpoweraustralia.com.au/) that's why it was considered as the smartest investments available in solar energy. Solar Thermal is one of the best ways to lower your carbon footprint and help protect the environment. Typically over 20% of a home's Green house gas emissions come from heating water. For many commercial businesses, such as fitness centers, water heating can account for over 50% of green-house emissions.

[Russ Bailey]

@ Angela - Why not just post the fact that you are a salesperson for that company?

That you are trying to get free use the web sites that others operate and pay for.

Russ

[Dave Turpin]

Sorry that I have been away for so long!

I finally bought a house and have been in the process of moving in... And getting everything up to code.

I bought a house built in 1947, so the first project was to rewire everything in non-metallic (instead of knob-and-tube) and replacing the load center with a modern system.

Bad news, though. I did make 2 240W solar panels (see my DIY post), but they did not survive the move. Actually, they didn't survive the family dog. A fall on their face on a concrete floor was enough to completely ruin them. Sad.

But... I have rebounded by making a couple smaller, sturdier 100W units. These ones are destined to be off-grid. Actually, I built them to keep the deep cycle battery for my backup sump pump charged. My "new" house has a stormwater cistern and basically al the gutters and the traditional weeps drain into the basement. If power was lost, the basement would quickly flood. That's why I got the battery backup. (Ridgid all-in-one system, I highly recommend it)

Anyway, I was thinking also about emergency lighting. The charge controller that I have is a 7A unit, and the sump pump itself has its own charge controller that automatically directs DC power to the backup pump's float switch when AC power is lost. I was considering powering a few 12V CFL lights, or these cool oLED strip lights that I found, off of the "load" portion of the charge controller. What I need now is a switch that goes "on" when the AC power goes "out". Where can I find such a switch? (We have such a switch for the emergency DC lights on the submarine, but I don't need a 1000A system)