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What’s watts with winter solar

February11

Over the previous month I have been spending my afternoons soldering on. We have a kilowatt of individual solar cells to stick together to build our own photo voltaic system.
As ever, it has been a learning curve. First, watch a lot of youtube videos. Second, figure out which of the youtube videos are made by people who have natural self confidence rather than knowledge or ability. There is a neophyte tendency with some to share their experiences, without then following up to admit when things go terribly wrong.
I am glad that our experiments have not, so far, been caught on camera. The first thing we learned was that the solar cells are extremely fragile. They have a similar consistency to eggshell, and must be handled delicately. Our second discovery was that only four fifths of them worked. Those that don’t tend to come in batches, so if you don’t test them first, you end up with whole strings which will decrease the efficacy of your system.
The cells themselves are fragile and also need to be protected from the elements – so that they don’t rust or become interesting places for various insects to set up home. For this you can use a type of silicone which will not discolour in the sun, or EVA plastic sheeting. We will try both, though the silicone is suspiciously expensive in small quantities.
Currently we have strings of twelve cells placed around the windows of the house in the twenty centimetre gap between the two layers of glass. We are getting a good number of volts, but the ampage is not high, meaning the overall power produced could be better. It’s also important to remember that at present the ground outside is completely snow-covered, meaning that there is a lot of reflected light. During the rest of the year, with no snow and the sun higher in the sky, we might actually get less light in those positions.
We have the inverter and charge controller necessary to build a system which will power the house from batteries when possible, and switch back to mains power when this runs out. We would need to have permissions and different equipment for a grid-tie system.
It takes about an hour to solder one string of twelve cells, so at least I can be doing this while we are learning about the other aspects of the system. I think that methods of encapsulation (and the pungent chemicals required) should wait until later in the year so that we can work outside in the fresh air or with lots of windows open – not possible right now when it’s quite so cold.

posted under Elements

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