The Lemon Fool

On one of my regular walking routes I pass a large 1950s detached house which is being comprehensively gutted and modernised.

It's close to completion and I recently noticed with surprise that since I last passed that way it has acquired an array of those black tubular solar water heating tubes on the south facing pitch of the main roof.

I was initially surprised as this is clearly a high end modernisation and I associate those black painted tubes as a basic obsolete technology from 20 odd years ago. But then on reflection I wondered if they could be experiencing a revival as a roof mounted solar source heat pump.

Was wondering if anyone knows if this is a thing? I suppose it would come down to a cost/benefit analysis comparing occupying that space with solar water tubes serving a heat pump with solar panels generating elec instead.

There is a realisation that for domestic water heating, collecting solar heat can be more efficient than using solar PV panels (which are only about 21% efficient). Heating domestic hot water tends to benefit from higher temperatures than space heating, especially if space heating is being done with a heat pump, so solar heating can make make a very good complement to a heat pump as it can produce high temperatures even in winter.

IIRC solar is far better at heating water than generating leccy. But the leccy attracts a FIT which the water heating doesn't, and in addition it is maintenance-free, which a water-filled system isn't. And finally the water system is desperately season-dependant. Even more so than the PE cells.

Solar water is probably far 'better' for the environment than PE, the benefits of which are distorted by guvvermint subsidies.

Mike4 wrote:IIRC solar is far better at heating water than generating leccy. But the leccy attracts a FIT which the water heating doesn't, and in addition it is maintenance-free, which a water-filled system isn't. And finally the water system is desperately season-dependant. Even more so than the PE cells.

Solar water is probably far 'better' for the environment than PE, the benefits of which are distorted by guvvermint subsidies.

I know people with both who rave about the solar water heating, even in winter it does a good job of providing a baseline of hot water. I'm pretty sure you need a 'special' type of cylinder though - most gas boiler cyls have one heating coil and AIUI these need a twin coil system, so installing during a refurb makes sense. Actually that reminds me, the plumber is coming today to talk about a new cyl, and the roofer hasn't tiled that end yet.......

With solar, at the 15p/kWh we get for export it is borderline in cost beween using gas or electric to heat the water.

The FIT and subsidies went several years ago

Paul

DrFfybes wrote:The FIT and subsidies went several years ago

Paul

For new installations, yes, but I carry on getting the FIT until 2036, RPI indexed. Crazy scheme. They now pay me about 71p per kWh, and I get to use the electricity. I almost feel guilty.

Surely even with new installations they still pay you for energy supplied into the grid? That's what I meant by the feed-in tariff.

Mike4 wrote:Surely even with new installations they still pay you for energy supplied into the grid? That's what I meant by the feed-in tariff.

Yes, however that is down to your energy supplier and there are no govt subsidies.

AIUI the FIT is/was a payment for what you generated, not what surplus energy you exported. So if you used it all in the house to heat water or charge a BEV you still got paid for generating it.

Baskerville Hall in Clyro has a pellet burning heating system on a FIT. It is stiflingly hot there as apparently they make money for every kg of pellet they burn, AND get free heating.

Paul

Mike4 wrote:Surely even with new installations they still pay you for energy supplied into the grid? That's what I meant by the feed-in tariff.

Yes, it is called SEG - Smart Export Guarantee. The best rates vary quite a bit. Octopus currently offer 15p per kWh for exported solar.

Note, your SEG account does not have to be with your electricity supplier, so you can shop around.

FD