Colin and Mo's solar freezer

It is was the year of Climate Emergency. Our dear David Attenborough had made us all think what we could personally do about it. I had worked out that quite a bit of our electricity usage was the 300 KWh or so that our freezer took. Well we would buy a 320W solar panel, put in on the workshop South gable. Amazingly the cost of the panel was not much less than the resin slates. It would generate the half KWh/day that a small freezer needs. A 2 KWh battery would keep it going overnight and for a few cloudy days. Winter is more difficult so a mains backup was essential.

The Solar controller stops the batteries being overcharged on very sunny days. The inverter turns the 12V from the battery into the 240V AC current needed by the freezer. The A+ energy rated 50 litre freezer was only 36 cm wide so fitted nicely into the workshop. Its annual consumption of 144 kWH/year made it fine for most of the year. It was rated at 60 W, but the initial power of motors is often much larger so I opted for a 1KW pure sine wave inverter.

A complicated contol system was needed. If the battery went low, say below 12V, I would need to switch to the mains supply, On the other hand, if the sun was shining brightly, the house solar system could supply the power and it would be best to charge the battery