Solar pv or solar thermal for space heating via thermal store

[Dalesdipper]

I’d like some advice and opinions please.
I have a 150 year old stone cottage ( 2 foot thick solid stone walls) some roof insulation and double glazed windows in a very cold exposed hill top position in the north western Yorkshire Dales.
we are planning to put underfloor heating downstairs and upstairs, standard radiators. It has 3 bedrooms and a single bathroom with one bath and a shower. 5 people live there.
it has a south, south east facing unshaded roof at one side.
we are proposing to install a thermal store of around 250 litres to run the central heating and to provide mains hot water via a heat exchanger so there are no issues with stored dhw.
we propose to install a condensing oil boiler connected to the thermal store. We may ( in the future) install and connect a wood burning stove to the thermal store too.
we would also like to add either solar thermal or solar pv with an iboost ( or similar) system to help heat the store. My questions are as follows,

1) would you choose solar pv or solar thermal ?

we won’t be installing batteries for the solar pv and are rarely in during the day so won’t utilise the electricity generated other than for heating the thermal store for space heating and hopefully dhw in the evenings.

we are wanting to reduce our oil usage and hope that a suitably sized system of solar pv or thermal would be able to provide a reasonable chunk of the space heating and water.
Do you think this is a feasible option ? And if so what sizes system would you recommend
Many thanks for any advice 😊

 

[Chuck]

I’d like some advice and opinions please.

Solar thermal is relatively cheap to install but I find it a bit disappointing because it works best in hot weather when you least need what it produces, i.e. warm water.

Electricity, however, is always useful. It's an expensive form of energy and I don't see that changing as demand is going to rise if gas boilers and internal combustion engines are to be phased out. You can use it to heat water and much more. A modern home uses quite a bit of power even when unoccupied (freezers and gadgets like routers are on all the time). I'm quite excited by the prospect of using solar PV to charge an electric car.

II wouldn't make this sort of decision based on guesswork. It'll be a big enough spend to deserve a few hours spent doing a proper cost / benefit analysis.

 

[Murdoch]

Op you would be surprised hot little hot water you will get unless it’s the summer.

there are 4 adults in our house and I originally installed PV, then added a SOLIC 200 to send the excess power to our hot tank BUT unless it’s the summer and it’s really sunny we still need to heat hot water via our boiler .

to expect PV to power your house, all your hot water AND charge an EV is a bit pie in the sky imho

 

[Dalesdipper]

Op you would be surprised hot little hot water you will get unless it’s the summer.

there are 4 adults in our house and I originally installed PV, then added a SOLIC 200 to send the excess power to our hot tank BUT unless it’s the summer and it’s really sunny we still need to heat hot water via our boiler .

to expect PV to power your house, all your hot water AND charge an EV is a bit pie in the sky imho

Thanks for your reply. I’m not interested in Charing an EV so not sure where you got that from but appreciate your input regarding hot water and space heating

 

[Ben-gee]

Solar thermal is the way to heat water, not PV.

 

[Murdoch]

Thanks for your reply. I’m not interested in Charing an EV so not sure where you got that from but appreciate your input regarding hot water and space heating

I mentioned EV because @Chuck did so I thought I'd add that for anybody reading this thread - too many people are getting the idea that PV could do everything ............

 

[Ric2013]

Thermal will give you more heat per sq m of collector area. It's likely to be cheaper than the same output of PV. That said, there's more plumbing and maintenance involved for a thermal system. Might be worth getting price comparisons of overall system costs.