Solar power in the garden
You won’t be gardening long before you feel the need for a little electricity.
I don’t mean excitement...
No, I mean power: the juice which runs your greenhouse heater, or lets you install a pump in your water butt so you can run a hose off it, or makes a heated propagator and thus transformation of your seed-sowing life possible.
This is rather tricky if you happen to be gardening on an allotment, say, or just a long way from the house. I kind-of manage with a Heath-Robinson extension lead from the garage through a missing pane in the window and hooked up out of strimmer reach along the fence. It’s all a bit dicey, though. It’s also expensive: I’ve never dared to work out how much it costs to have my all-singing, all-dancing propagator running all spring, let alone the greenhouse heater, but it’s my bet that it accounts for quite a big chunk of our winter electricity bill.
All this is not very sustainable, and goes against the grain of my generally low-impact attitude to life. If I’m trying to cut food miles to nearly zero, it makes no sense at all if the only way I can do that is by sucking energy from a power station burning its way through tons of fossil fuels. I want to get as close as possible to zero energy miles, too.
Luckily for me there are a lot of people out there applying their considerable skills and invention to solving the problem of providing energy in the garden without having to rely on conventionally-supplied electricity. The solution, it turns out, is solar: makes sense, when you think about it, since everything else in the garden relies on sunshine too.
It may surprise you that not all are colossally expensive, either (though some are), things like a solar powered water butt pump system, or solar lighting are all quite affordable. However here are a few of the sunny solutions I’ve found lately for all your gardening energy needs.
High Budget: Photovoltaic glass greenhouses
Oh, I covet one of these. It makes a lot of sense: turn the glass in your greenhouse (by definition, sited in a sunny spot) into a solar power generator.
A solar greenhouse produces around 600-900 kW/h each year – that’s around a third of the average energy required to run a whole house, and rather more than you’d use for running a greenhouse heater through an average winter. And yes, before you ask, they do work when it’s not sunny (and that means through November to February) – just not quite as energetically (sorry) as in summer, that’s all.
Cost: around £7,000 for a 10x8ft greenhouse
Low Budget: Solar irrigation
I spotted this one at the Edible Garden Show and it struck me as one of those ideas that’s so obvious you wonder why nobody’s thought of it before. You want to do more watering when it’s sunny, right? So that’s when you’re using your water butt pump most often. So why not use the sun to switch it on?
This automatic system runs roughly every three hours (that’s the time it takes for the solar panels to recharge the battery). You can adjust it via the drippers so your plants don’t get swamped: once you’ve got the delivery level right, your greenhouse or pots plants are watered automatically once every three hours when it’s sunny, and less often (because it takes the battery longer to charge) when it’s cloudy. Genius.
Cost: about £80
No Budget: A recycled black radiator and a bit of spare piping
Now this is the kind of ingenuity blokes in flat caps on allotments are famous for. Spotted on the Leeds and District Allotment Gardeners Federation stand in the Great Pavilion at Chelsea: a solar powered hot box made out of an old radiator painted black, an ice cream tub, and a load of old piping.
To explain (as best I can, as I’m a little hazy on the details, not possessing a flat cap or being a bloke): it’s based on the principle of the back boiler, an old central heating system used in houses. You paint your radiator black and mount it in a sunny spot encased within a box made out of recycled double-glazed windows, so the heat it absorbs is insulated. The water in the radiator is heated by sunlight and rises up the pipe, across the top of a raised bed and then down underneath the soil, linking back up with the radiator in a circuit so the heated water is continuously driven around and under your crops. Oh, and the ice cream tub is inserted into the pipe and acts as a vent.
This is the equivalent of having a heated soil cable underneath the soil, warming it to balmy temperatures and allowing you to germinate seedlings early, keep things going for longer, grow heat-lovers like watermelons… oh, all sorts of uses, and you don’t have to so much as flick a switch. You can’t exactly turn it on and off, or adjust it in any way – but I can’t see why you’d particularly need to.
Cost: Nothing, unless you count the few quid for the icecream.
You won’t be gardening long before you feel the need for a little electricity.
Low Budget: 
No Budget: A recycled black radiator and a bit of spare piping