The 12V solar panel for battery storeage

Colin's Solar panel 12V battery storage

Our existing 1.8 KW solar panels have now generated, on average over 7 years, 3.9 kWh/day. They give us free electricity during the day and send any surplus to the grid. But they are no use during the night and cannot be used in a power cut. I was being bombarded with sales talk for battery storage but it was expensive. The price of solar panels is falling, and I was able to buy a 0.25 kW panel for £171. This should give us ~0.55 kWh/day - enough to keep our big TV going for 3.4 hours. I thought I would do my own storage with this panel and 12V lead-acid battery storage. The timber support for the panel cemented in place

The timber support for the panel cemented in place

There was a good south-facing wall next to our bicycle shed. I made a sturdy support for the panel using up some spare timber. With its legs in concrete, it was really firm. Lifting up the heavy panel was easy, step by step with Mo. 0.25kW at 12 V correponds to 21 amps in full sunshine and a solar controller is needed to stop any overcharging of the battery. My CMG 300W controllor cost £20. To run the TV requires an "invertor" to turn the 12V into 240V. I bought a "Pure Sine Wave" Invertor from Andself for £38. The output has its own cable to a socket in our lounge. The solar controller and invertor in my bycycle shed

There are many battery types now, but I chose two Halford's 115Ah lead-acid batteries as the cheapest solution, given that I had plenty of room. Together they cost £190 and store 2.76 kWh, or nearly 5 average days charge. The system works fine and keeps our TV going on normal days. During a long run of cloudy winter days, the inverter cuts out and you just have to switch plugs. The two slow discharge batteries