Solar Panel - Prototype One

After removing all the unusable bits of cell from the package I ended up with 99 cells that were at least full width or full height. I'm amazed at how fragile the cells are so its not really surprising that a few didn't survive the trip.

I found that securing any cracked cells to the glass with tape helped to avoid any further damage but get it right. There is no chance of removing the tape without destroying the cell. I'm not sure whats going to happen when the tape has been in the hot sun for a summer but hopefully everything is so tightly sandwiched that it won't matter.

The back view

I also found that soldering the panels while they were in contact with the glass was a stupid idea. The glass conducts the heat away far too fast to be able to get a good joint.

A bit of forward planning would have gone a miss. I ended up having to run a wire down the middle of the panel because I oriented both strips of panels the same. This meant the positive ended up at the top. No good when I want to connect them in series.

The front view

The silicon sandwiched between two sheets of glass takes a long time to set. Seal it and put it away for a week before playing with it. I used a bathroom silicon that reacts with water so hopefully the remain air trapped between the glass will be fairly dry.

Best result so far was 1.2Amps at 5.2 volts = 6.24w. Which is reasonably pleasing considering the state of the panels and the terrible soldering job and having to run the connecting wire down the center of the panel.

The panel cost about $6 for the cells and a couple of dollars for silicon and connectors. Call it $10 which makes it ~$1.60/watt. A lot cheaper then buying them but no 25 year output warranty.

Getting moisture inside the panel will be the biggest issue. We'll see how they go when I mount them outside. A local company Terranova operates a waste exchange. One of their clients is advertising factory second double glazing for free. I'm thinking I might be able to pop the end off and slide the cells inside. This would probably keep them dryer and be a cheap source of glass.

I metered a couple of power points around the house for a few months and found the following;

Fridge uses 0.72KWh/day
Internet connection, wireless router and switch use 0.24KWh/day

My first goal is to get the internet gear running off the panels. Assuming I get 6 hours of sunlight a day (very optimistic) I'd need a 40W solar array so maybe if I have a 100W solar array I might be able to do it. So far I've observed that 12 cells is required for 6W so I'd need 200 cells to archive this goal. Sounds like a lot but its how many I ordered so all I need now is more glass and lots more patience.

DIY Solar Panels

I've been reading around the 'net and found there is a bit of a buzz around building your own solar panels. I've always liked the idea of producing my own electricity and with the amount of solar radiation arriving on our roof everyday it should be quite practical. Only the financial cost has stopped me so far. For a reasonable sized, grid tied, system I’d be looking at well in excess of $NZ10,000.

One possible solution is to make my own photovoltaic panels. I’ve ordered 200 broken solar cells from a seller on e-bay. They cost me $NZ120, with over half that cost being shipping from Miami. I estimate each cell should give me, at worst, about 0.6W which should give me about (0.6 * 180) 108W. I’m using 180 to allow for some unusable cells and some mistakes. This works out at about $1/Watt. Add to that some building materials to bring the cost up to $1.50/Watt which is about 20% of the cost of buying the cheapest professionally made panels and 10% the cost of the more expensive ones. I’m expecting to get better than 108W, but I’ll keep my estimates low so I’m not disappointed.

Of course, my panels won’t come with a 25 year output guarantee, but I’ll take the risk.

After my paypal payment cleared the shipper sent the package, 5 days later it would have been at my door but we were away, camping at Okains Bay. I suppose I’ll have to wait until tomorrow, which is just as well as I’ve got unpacking to do.

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Shipment Activity Location Date & Time
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Attempted Delivery NEW ZEALAND 01/16/10 1:20pm
Out of Foreign Customs NEW ZEALAND 01/15/10 4:59pm
Arrived Abroad NEW ZEALAND 01/15/10 1:20pm
International Dispatch UNITED STATES 01/12/10 4:44pm
Arrival UNITED STATES 01/12/10 4:43pm
Electronic Shipping POMPANO BEACH FL 33077 01/11/10 1:09am

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We use about 8000KWh (kilowatt hours) a year. If we assume that 60% of that is for hot water (4800KWh) and that a solar + gas hot water system would supply all we need that leaves us with 3200KWh. If we put gas in for hot water we would probably cook on that as well, removing our electric stove, but I'm ignoring that for the moment).

3200KWh / 365 (days in a year) is just under 9KWh/day. Assuming 4 hours of usable sun a day that would mean I'd need a 2.25KW solar array to supply our needs.

There are a lot of assumptions in there and factors I'm ignoring (like storage, dark winter weeks, peak loads etc) but that gives a rough indication of the size of array I'd need.

At $1.50/Watt I'd need to spend $3375 on the panels, which is not a lot of money when compared with using professionally built panels. I'm not sure I'll ever get there but there's the target.