Part 3 - Panels, Panels and more Panels

Collecting the Sun

The fundamental basic of anything solar is that  we need to collect rays of sun and convert them into something useable. A Solar geyser is easy, its just a flat plate collector that uses suns heat rays to heat water in pipes.
Producing electricity or more correctly electric current using sun rays is slightly different. We need to use photo voltaic cells.

Solar (photo Voltaic) panels are made from a special silicon layers that react when exposed to sunlight causing electrons to flow from one layer to the next. A solar panel would typically be made up of solar cells, solar modules and a solar array.

There are two types of silicon in use, Poly-Crystalline and Mono-Crystalline.

Poly is slightly less expensive than Mono but Mono is slightly more efficient. Mono-Crystalline is a purer form of silicone than Poly-Crystalline which explains why it is more efficient but also costs more.

Just how much...?

Lets start with the efficiency, according to research mono-Crystalline has an efficiency of about 15-20%, Poly-Crystalline has an efficiency of 13-16%
Mono-Crystalline panels have a lifespan of 25 years whereas Poly-Crystalline have only a 20 year life span.

The costs of Mono-Crystalline panels are about 10% more than Poly-Crystalline, for the slight difference in efficiency it just does not seem worth it. Most solar companies in South Africa are not manufacturing or importing Mono-Crystalline panels.

I decided to work on a 250 Watt panel size as it gives me the best power/current/wattage ratios.

Typically 250 watts of panel will give you an open circuit voltage of 38 volts and current flow of about 8 amps. (these are specified as 24 volt panels)
Our example system is configured for 48 volts which means we need 2 panels in series to get 48 volts.

Remember watts in = watts out form Part 1...

When we add the panels in series the voltage adds but the current stays the same, so 2 x 250 watt panels in series will give me the desired 48 volts but the current will be 8 amps.

I would need to configure a few solar panel arrays in this way to get my 1000 watts connected to my trip switches, fuses and inverter.

Watt are the Costs..

Locally we can buy 2500 watt panels at R 9.59 per watt, this means a 250 watt panel will cost
R 9.59 x 250 = R2 398.00 (ex VAT) R 2 734.00 inclusive

From China I can buy 250 watt panels for 0.54 USD per watt (landed cost), this means a 250 watt panel will cost  $ 0.54 x 250 = $ 135.00 converted at today's rate (12.1221) R 1 637.00 on this we will pay VAT once it lands so the cost will be R 1 866.00 inclusive.

This means the Solar panels from China are 32% less expensive than the locally sourced ones.

If we ordered a container load and had it shipped here and not air cargo it would cost even less, I am not sure why we are paying such a premium for solar panels here.