For the last couple of years we have been playing with hydroponics and auto-watering (e.g. see here). We don’t have mains power in the greenhouse, and though I could put it in, it seemed fun to play with running it from a 12 volt system. That created its own issues like finding 12 volt time switches (I couldn’t, and had to modify a mains one – see here) … but it has worked really well. However, it has required charging the battery every week or two. And, very annoyingly, I forgot to detach the timer from the battery over winter, or float charge it, so it over-discharged and had to be junked.
So, this year we decided to go for a proper off-grid solution that uses a 15W solar panel to keep the battery topped up. We mounted the panel on a shelf up high where it will be well lit, but not block light from any plants.
This feeds a solar regulator that avoids over-charging the battery, and also prevents the battery from being too discharged … I don’t want to buy one every year! It has only taken an hour or so, and first indications look good – time will tell whether it can provide enough power, but it should be slightly over-specified.
We’ve also decided to dump the grow-bags and drip-watering we used last year in favour of a pure hydroponic solution. So, we have a 3 metre channel on a low shelf at the back of the greenhouse (see here for supplier), with eight pots. The aim is tomatoes, melons and cucumber in that tray, and chillies and peppers in the original pots, with rocket and the like in the like in the flood and drain set-up.