It’s a bit overdue and only a short post, well at least that’s what I think as I start to type it, but I promised Pat over at Solarbeez a run down of our solar water heating system. It seemed relevant now as we are starting to feel the benefits, in fact we felt the benefits in April with a whopping eighteen days heating free.
Ok, that’s not entirely down to the solar system, or entirely true, in that the house captures quite a bit of heat as the sun shines in the morning and evening and then retains it pretty well. The midday sun stopped heating the house in early April as the height of its arc moved beyond the terrace roof, I had worried that this was a little too early and that we would benefit from a slightly higher roof, but as it happens, with the warm weather, the timing is about right. The little white lie I slipped in is that I did fire up the boiler on occasion to get the water up to a minimum 50c but not for more than an hour or so on the days when the sun just wasn’t strong enough for long enough. Incidentally I read that most domestic systems heat the water to a minimum of 60c to prevent the very small possibility of the bacteria that causes legionnaires disease forming. It is an extremely small risk and so we save our wood and 50c is more than hot enough for a decent shower.
Ok, here’s the technical bit, except it’s not that technical as I didn’t get that involved other than to specify that we wanted evacuated tubes. So we ended up with 30 one meter evacuated tubes fitted at a 40 something degree angle on our south facing roof. These are feeding a 300 litre multi element tank via a 14 watt pump which circulates the fluid as it heats and transfers that to the water. My observations so far show that as long as we have a clear day with the sun shining the outside air temperature has to be about 15c to provide us with a full tank of 50c+. Conversely a 25c day might only heat the water to 40c if it’s cloudy; it’s all about the sunshine!
Our boiler is a big old wood burner with coal auto-feed attached just in case we need to run the heating for prolonged periods in really cold weather although it was relatively mild this last year so we stuck to the wood (except for a few lazy days)
If we ever finish the house then the boiler will heat 12 radiators and the kitchen and bathroom under floor heating. It’s main job at the moment is topping up the hot water on cloudy days, like today, and an arm full of old chopped up pallet board took the water form 35 to 55c in about half an hour. More than enough for our ablutions, the washing up and indeed most of tomorrow, by which time the sun will have done it’s job.
All in all I would recommend a solar water system if you live it the appropriate climate, despite the rather long return on investment for us as we are only saving the burning of wood which is free (other than my time and the chainsaw) If you are lucky enough to live in a country offering rebates or other incentives then I’d say go for it if you have the money to invest, if only Poland was a as forward thinking and as green as some of it’s European counterparts.
Mind you, now that we have pigs (more in my next post) maybe we can start to generate electricity from the methane The Good Life way!