One of the many downsides to solar is it's price. Just looking at a 100W panel, we can see the prices are sometimes a bit high, running about $1.15 per watt. Additionally, its sometimes difficult to scale up without modifying the exit wire connectors, where if you do, your warranty will probably be voided.
Although there's nothing wrong with straight up buying solar panels, if you're willing to put in some work, you can spend significantly less money per watt of power.
First, you'll need to go scavenging for broken solar cells. Many companies sell solar cells that have been rejected by their quality departments due to chips, cracks, or some unaesthetic quality. They function perfectly fine, its just that they look bad.
We found and Ebay dealer where you can put in a bid for un-tabbed broken solar cells, and were able to grab around 70watts for only $8.00
Or, if you want to avoid bidding, you could always buy broken solar cells directly, where 1kg of solar cells, almost 280 Watts of power, sells for around $60.
To make our solar panels, we need to obtain the following items:
Soldering Iron: $8
Solder : $8
Tabbing wire, flux pen, diodes (If you're planning on making panels that generate more than 6 amps of current, you'll need a better diode) : $15
Electrical Wire: $12
Panel Backing for Solar Cells (we used wood from home depot, but pegboard could work too): $15
Note: A 4ft x 8ft panel will give you enough surface area to generate around 70 watts using the broken solar cells.
You may already have some of the above items in your possession, so not including the tools we need, the total spent on materials required to fabricate a solar panel, scaled per 100 watts (just for comparison sake), is around $50, less than half of what you would spend on a normal solar panel.
Soldering the solar cells together
The next step is to solder your solar cells together using the tabbing, solder, and flux pen. You'll want to attach the tabbing from top of one cell (positive side), to the bottom of the next cell (negative side), as seen in the pictures below. Each cell is approximated 0.5Volts, and to charge a 12 Volt battery, you'll need around 17 Volts for your solar panel. For one panel, we advise to use around 34 solar cells minimum.
To connect multiple columns, just use bus wire tab to connect them as seen below.
Using a glue gun, place small dabs of glue on the underside of the solar cells to fix them to your backing panel. Be careful, as the solar cells can be very brittle when handling.
It may not look like much, but using a voltmeter, we were able to detect that our solar panel was generating 73 watts in indirect sunlight.
And that's it! We've built a low cost solar panel. In our future posts, we'll cover how to finish an off-grid solar setup.