Thermal Solar Power - worthwhile under the upcoming RHI scheme?
frozen_wastes
Forumite 119 Posts
Afternoon,
Originally my future home project was to simply replace my 18 year old G rated boiler with a straight swap A rated boiler.
How ideas grow arms and legs! Then I convinced myself that what I wanted was a conversion of my plumbing system from open vent to sealed. Then I saw the price of unvented cylinders and thought "well it's an extra 200 - 300 quid for a twin coil cylinder. That'll make a solar retrofit in the future somewhat easier".
So now I'm in the position of evaluating the benefits of hot water solar. I'm looking at a complete Vaillant solution - boiler, cylinder and panels. At Plumbnation, there's a 3 solar panel system with evcuated tubes for £3000:
http://www.plumbnation.co.uk/site/vaillant-aurotherm-exclusive-solar-heating-system-vtk-tube-collector-package/
So with labour costs, I'm reckoning the total price will be around £4000.
I've heard such a system will probably provide 1500kWH. Which is around £100 a year saving off my LPG costs. So 40 years to pay back without subsidies. Not worth it in my view (even with LPG price increases).
Now I've heard of a new Renewable Heat Incentive that's likely to come out this June. Apparently solar thermal will pay around 18p/KwH. http://www.rhincentive.co.uk/eligible/levels/. Assuming this all turns out to be true, it makes solar thermal pay for itself after about 10 years.
So, my basic question. Should I go for that Twin Coil Cylinder, or is the RHI just a load of rhetorical Nonsense for now?
Originally my future home project was to simply replace my 18 year old G rated boiler with a straight swap A rated boiler.
How ideas grow arms and legs! Then I convinced myself that what I wanted was a conversion of my plumbing system from open vent to sealed. Then I saw the price of unvented cylinders and thought "well it's an extra 200 - 300 quid for a twin coil cylinder. That'll make a solar retrofit in the future somewhat easier".
So now I'm in the position of evaluating the benefits of hot water solar. I'm looking at a complete Vaillant solution - boiler, cylinder and panels. At Plumbnation, there's a 3 solar panel system with evcuated tubes for £3000:
http://www.plumbnation.co.uk/site/vaillant-aurotherm-exclusive-solar-heating-system-vtk-tube-collector-package/
So with labour costs, I'm reckoning the total price will be around £4000.
I've heard such a system will probably provide 1500kWH. Which is around £100 a year saving off my LPG costs. So 40 years to pay back without subsidies. Not worth it in my view (even with LPG price increases).
Now I've heard of a new Renewable Heat Incentive that's likely to come out this June. Apparently solar thermal will pay around 18p/KwH. http://www.rhincentive.co.uk/eligible/levels/. Assuming this all turns out to be true, it makes solar thermal pay for itself after about 10 years.
So, my basic question. Should I go for that Twin Coil Cylinder, or is the RHI just a load of rhetorical Nonsense for now?
8.9kw solar. 12 panels ESE, 16 panels SSW. JA solar 320watt smart panels. Solar Edge 8KW HD wave inverter. Located Aberdeenshire
0
This discussion has been closed.
Latest MSE News and Guides
Replies
Your '40 years to payback' (£100 a year saving - on a £4000 system) is too simplistic. £4,000 invested long term will earn £160 a year interest invested @ 4%.
In any case whilst a large system with 3 evacuated tube panels might well produce 1,500kWh pa much of this will be in the summer and you might have difficulty using the hot water.
RHI will change the equation drastically if solar thermal qualifies, but then you have to factor in the additional cost of a system fitted by MCS approved firms.
Personally I'd prefer to see lower kit prices for the solar hot water systems. The panels don't look too complicated from a materials or engineering point of view. I'd have thought the manufacturers would be able to figure out lower production costs for these units.
Applying this formula, I would be short of £2000 if I installed today, and sold my house tomorrow. There's also depreciation to consider, I reckon such a system would probably last 30 years before requiring replacement (less if these vacuum tubes are easily damaged by storm debris).
So without RHI, the Vaillant tubes don't look like any kind of money saving deal. Solflex tubes are about 2/3 the price, but I have no idea as to their reputation. Solflex could just about be worthwhile without any subsidies.
You might save £100 a year with a large 3 evacuated panel system. - with LPG - not if you have gas
However do you really think the panels and connections stuck on a roof will last 30 years without deterioration?
What about the pump, electronics, valves and special to purpose HW tank?
Also people tend to ignore the electricity consumed(at daytime rates) to run the pump and electronics. The Government commissioned report on eight solar thermal systems found the cost of this 'parasitic' energy to be quite high in relation to savings.
Time to lay solar thermal ideas to bed. I'll just stick with the boiler replacement and plumbing conversion.
I absolutely agree with that and when the solar pump comes on then my owl monitor jumps to 500 watts from a steady background of around 270 watts. In our case the PV system is providing enough energy to `pay` for the solar pump. The background cost of running the solar thermal system should not be overlooked
The solar system will need a bit of maintenance eg the antifreeze needs to be changed every 5 years and we already had one faulty collector sensor changed due to an installation mistake. The plumbing all looks quite complicated