Last January we finished putting solar hot water panels on our Devon eco lodges. Lots of people have asked about them, so here are a few tips for other DIY-ers
The panels mean Honeysuckle Nuthatch and Beech Lodges all their hot water from solar panels (with immersion top up). Honeysuckle and Nuthatch Lodges have a single west facing panel each. Our large Beech Lodge has two – one on each of the east and west facing slopes. The control system (all part of the kit) chooses which is producing the hottest water and switches the pump to that panel on.
The shower in Beech Lodge is still electric, but this will be switched in autumn 09. We also plan solar panels for Otter Cottage [update – done now]. The delay, though not ideal, also means we’ll have more time to gather comparative data – so we should be able to report back later on the economics and pay back times.
Meanwhile, we’ve been really impressed with how good the panels are. We ended up doing the installation ourselves (well, Ian did it and Maggie made the tea). We were eligible for a grant from Renewable Energy for Devon (RE4D), but we would have had to use one of their recognised installers, and that pushed the price up much higher than the grant was worth – so we went DIY. So to spread the word, here’s some of what we’ve learnt. If you’ve got other questions, gives Ian a ring or email us at email@example.com.
Evacuated tube solar collectors are said to be the most efficient at converting solar energy to heat water. Navitron came top in my list of suppliers for their no-nonsense approach and competitive prices, so I went with their kits.
I bought the Solarkit1 comprising a 20 tube solar collector, a 175l thermal store (hot water tank), the TDC3 controller, an expansion tank, the circulation pump and extras such as the anti-freeze, the filling pump and some valves.
Extras you will need to buy: This amounts to more than you first think. It is essentially the copper pipes to connect up the water in and out, the solar circuit and the expansion tank. You also need drain valves, immersion heater element and a blank cover for the alternative immersion heater hole.
However, when you try and squeeze this into an airing cupboard in a way that allows you to then get the tank in and cater for the possibility of one day taking it out again, you find you need a lot of copper elbows, compression fittings, reducers from 22mm to 15mm and so on.
Plan it as best you can before starting or you will be up and down to the plumbers merchant (Screwfix is handy for next day delivery) throughout the job.
Getting started… I won’t repeat anything on the instructions – they are clear and easy to follow. These are just a few observations from my 3 installs that might make life easier.
When you get the Navitron kit (or any other)the most exciting part is the Solar collector or solar panel. By all means have a look at it, but remember that it is really the last thing to install and the easiest part.
So, out with the old and in with the new. The new is a ‘thermal store’ rather than a hot water tank. Basically, the tank is filled with water that stays in there. Cold water passes through a coil in the store and picks up heat from the tank, exiting as hot water. The 2 advantages of this are:
1 – you get mains pressure hot water
2 – the hot water from the taps never stands around in a tank, so there is no legionnaires risk. Mainly of relevance to us as a commercial establishment where steps have otherwise to be taken to avoid this problem.
With the airing cupboard empty I fitted the expansion vessel. This is needed because the fluid that runs around through the coil in the tank and up through the solar collector is pressurised. The pipe is the old hot water pipe that will be used again as it is already hooked up to taps round the lodge. All I need to do is fit it to the hot water outlet of the thermal store…
Assembling and fitting the solar collector :
1/ Do what you can on the ground. Make the frame up and be sure that it is square (measure the diagonals) before tightening up. It is important or the tubes will not lie straight and you will struggle to fit them at an angle – glass does not like being bent!
2/ Loosely fit all the jubilee clips to the bottom of the frame. Easier now than on the roof.
3/ Make sure all the rubber boots for the tubes have holes in the end. They often are not quite punched out in manufacturing, so poke a screwdriver through them or they will not slide onto the tubes properly. Wet the end of the tube to make it easier.
The frame is now ready to take up on the roof, and the tubes with boots on ready to be passed up.