Integrating solar into existing power systems

I am currently looking into the feasibility of all forms of renewables as a supplement to existing power supplies. I have had a number of amorphous PV panels on test for six months with a quite small load. Any thoughts on how to integrate a small scale system for lighting(using LED lamps) would be appreciated ! Simon.

Hi Simon,

When you mention 'existing power supplies' do you mean mains electricity or a battery powered system? The two are fundamentally different. To integrate solar panels into a battery system is trivial - simply connect the panels into the system via a regulator.

For mains supplies, integrating is harder. You can get inverters to convert the DC electricity from the panels into 240VAC to connect to the national grid, but they are not cheap, and it's not DIY wiring! For a small scale system of less than a few hundred watts it's not worth the effort and the cost. Besides, LED lights are usually low voltage DC types, so converting from DC to AC and back again is a bit pointless.

An alternative is to run the lights from a switch that can be set to either 1) a battery bank that is charged by solar panels or 2) a mains-powered 12V power supply. Most of the time you can run the lights off your batteries, but when they begin to get low, simply switch over to the mains supply. It wouldn't be terribly hard to create a circuit to do it automatically when the voltage began to drop.

A friend of mine runs the lighting in his kitchen from such a setup, and it has worked very well for him.