Solar power on roofs - more viable with energy price hikes?

[Gareth J]

Not forgetting oil is unlikely to remain at 4p/kWh (in fact I think you’d struggle to get it for that now, given the current rises…)

Yes, displacing even a portion of elec and fuel consumption with some known price thing has value, even if that's more expensive than current prices. You're insulating yourself from the unknown future.

 

[fizzy]

Mate of mine just told me he pays 15 cents per kw/h in France for electricity. That is about 12p. If nuclear is so expensive how can that be? In fact France want to sell it cheaper than that but aren't allowed to by the EU.

 

[addjunkie]

Mate of mine just told me he pays 15 cents per kw/h in France for electricity. That is about 12p. If nuclear is so expensive how can that be? In fact France want to sell it cheaper than that but aren't allowed to by the EU.

Dont know, perhaps France is run by a non profit organisation, power for the people an all that. Where as here, each slice of the system is a profit making organisation. We have generators who need a margin of profit, the DNOs who need profit, the wholesaler, then the call center selling it to you, who are also supposed to make a profit.

was it not simpler before all this complexification, swapping tariffs and suppliers etc all wanting a slice.

 

[fizzy]

Dont know, perhaps France is run by a non profit organisation, power for the people an all that. Where as here, each slice of the system is a profit making organisation. We have generators who need a margin of profit, the DNOs who need profit, the wholesaler, then the call center selling it to you, who are also supposed to make a profit.

was it not simpler before all this complexification, swapping tariffs and suppliers etc all wanting a slice.

There is no profit in the UK. Witness all the companies that have gone bust and even gas power stations going bust.
France don't pay subsidies for wind and solar.

 

[Gareth J]

Mate of mine just told me he pays 15 cents per kw/h in France for electricity. That is about 12p. If nuclear is so expensive how can that be? In fact France want to sell it cheaper than that but aren't allowed to by the EU.

Not enough information to say.

What wholesale price do french nuclear power stations get paid? How do they compare with existing and proposed new UK nuclear. Maybe they're cheaper to run in France, maybe the UK demands more expensive safety restrictions, maybe EDF overcharge us for the power they make in their UK stations. Maybe they're much of a muchness in price but their infrastructure is loads better. Pretty unlikely though, considering the strike price for Hinckley I linked to previously was over 9p/kWh.

 

[Gareth J]

Mate of mine just told me he pays 15 cents per kw/h in France for electricity. That is about 12p. If nuclear is so expensive how can that be? In fact France want to sell it cheaper than that but aren't allowed to by the EU.

Just had a little look around.

It looks like, as is so often the case, it's complicated.

France electric was state owned until 2007. Even now, the biggest company, EDF is majority state owned and the government sets the price of the standard tarriff.

They have very much been hit by recent price hikes in wholesale costs as well as the rest of Europe. But France's government have intervened more drastithan ours;

"[The French] finance minister Bruno Le Maire, who has said prices would have leapt by 35 to 45% without state help, has handed €100 (£83) to 5.8million low income households to help with extra costs."

Why are energy bills so much cheaper in France?

Emmanuel Macron’s government has limited gas price increases to 12.6% and promised further help after the cap ends in April.

metro.co.uk

Though, as wholesale costs have risen beyond even new nuclear now, that's bound to also help

 

[daleyd]

Mate of mine just told me he pays 15 cents per kw/h in France for electricity. That is about 12p. If nuclear is so expensive how can that be? In fact France want to sell it cheaper than that but aren't allowed to by the EU.

Because it’s heavily subsidised by the french government - Edf is mostly state owned, the stations are almost all state owned, and the electricity is sold to the state.

 

[Trevorleach]

Potentially daft question, but is/can a reverse cycle air con machine used in heat mode be as efficient as an ASHP?

 

[Trevorleach]

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I haven't chosen the cheapest £/watt as would prefer black panels and the shape of the roof favours something a bit more energy dense than the cheapest. I've been telling you for quite a while that these are about the price of it although I do notice that prices have dropped a bit more since I last bought a set.

At those prices, given an expected 20 yr lifespan, a kWh is cheaper than oil @4p. But I won't be able to displace that much oil consumption anyway. Hence, to make them viable, need to be combined with some other electrical consuming thing. A mini aluminium smelting plant maybe.

Edit; PS; heating oil is currently at about 6p per kWh. And that's assuming whatever you're burning it in is 100% efficient.

Very useful link thank you

 

[dobbslc]

Back to towards topic for a moment. If it's of interest, I just priced a brand new setup (solar sparky this time) 3.9kW all required bits and bobs for a DIY install on a tin roof, £2200 Inc vat.

That's reasonably cheap, 390W panels. You might get it a bit cheaper if you had more space to play with but I was limited to choosing ones that tesselated well.

A "hybrid" inverter, ready for batteries at a later date would add a couple hundred.

If I didn't already have 4kW array, it'd be a no brainer. But it's diminishing returns at this point. I'd only be doing it to cut heating oil usage a bit more really. Without something hungry like a heat pump or electric car to hoover up some more generation, it's not that sensible. But then, not every decihas to be brutally sensible!

I've had a look on the website but don't really know what I'm looking for
Is 4kw a decent size for a family of 4?
We're on oil but I want to use solar to heat a cylinder of water as that is what costs the most, I figure we could have free hot water all summer.
I'll need a much bigger cylinder or heat store but don't know what way to go.
Any advice?

 

[Ubique]

Potentially daft question, but is/can a reverse cycle air con machine used in heat mode be as efficient as an ASHP?

That's what we use to boost the heating as needed, the inverter controlled AC is a lot more efficient than the old on/off stuff. We've had a dual split installed for three years and there is no noticeable increase in annual energy consumption. We tend to set the heating to 18 or 16 degrees depending on the zone during the day, to keep the dogs & birds comfortable then boost for 30 mins or so with the reverse cycle AC, allowing the gas central heating to take over after that. I'd imagine that heat pump running costs would be similar but be careful with the ambient temperature specification - it's a bit likethe reverse of a coolbox vs. a fridge, one will chill so many degrees below ambient whereas the other will chill to an absolute temperature.

 

[Gareth J]

I've had a look on the website but don't really know what I'm looking for
Is 4kw a decent size for a family of 4?
We're on oil but I want to use solar to heat a cylinder of water as that is what costs the most, I figure we could have free hot water all summer.
I'll need a much bigger cylinder or heat store but don't know what way to go.
Any advice?

For me, a lot of the obstacle to putting it on DIY is the knowledge. Knowing what mounting to get and how to fit it, what connectors and wiring type etc. Once you've done a type of install, it's really straightforward. I've only done one, on a tin roof, myself so can't comment on tile fixings.

Regarding size, the DNO are obliged to automatically let you connect with 3.68kW of capacity. So a lot of installations just go with that. You can oversize the array to just over 4kW of panels on most inverters while the inverter caps at the 3.68KW of juice.

For your own installation, limitation might be on roof size/shape as well as what the DNO say you can have or what you decide to spend. So first, check the size/shape of roof, tesselate size, shape power and budget of panels you want and, if it exceeds ~4kW of panels, you'll have to fill in some forms with the DNO to see what they'll allow and go from there. You could chance it without DNO approval but shouldn't be prohibitive on a domestic install anyway.....or pay an installer to sort all it out!

 

[Trevorleach]

That's what we use to boost the heating as needed, the inverter controlled AC is a lot more efficient than the old on/off stuff. We've had a dual split installed for three years and there is no noticeable increase in annual energy consumption. We tend to set the heating to 18 or 16 degrees depending on the zone during the day, to keep the dogs & birds comfortable then boost for 30 mins or so with the reverse cycle AC, allowing the gas central heating to take over after that. I'd imagine that heat pump running costs would be similar but be careful with the ambient temperature specification - it's a bit likethe reverse of a coolbox vs. a fridge, one will chill so many degrees below ambient whereas the other will chill to an absolute temperature.

Thank you, I have two a/c, one is 15 odd yrs old so not inverter, pretty certain other is an inverter sadly I installed it in the main bedroom so not much use for heating the rest of the house!
Oh well it was just an idle thought.

 

[Ubique]

For me, a lot of the obstacle to putting it on DIY is the knowledge. Knowing what mounting to get and how to fit it, what connectors and wiring type etc. Once you've done a type of install, it's really straightforward. I've only done one, on a tin roof, myself so can't comment on tile fixings.

Regarding size, the DNO are obliged to automatically let you connect with 3.68kW of capacity. So a lot of installations just go with that. You can oversize the array to just over 4kW of panels on most inverters while the inverter caps at the 3.68KW of juice.

For your own installation, limitation might be on roof size/shape as well as what the DNO say you can have or what you decide to spend. So first, check the size/shape of roof, tesselate size, shape power and budget of panels you want and, if it exceeds ~4kW of panels, you'll have to fill in some forms with the DNO to see what they'll allow and go from there. You could chance it without DNO approval but shouldn't be prohibitive on a domestic install anyway.....or pay an installer to sort all it out!

I didn't know about the DNO approval, thanks for the info.

 

[Ubique]

Thank you, I have two a/c, one is 15 odd yrs old so not inverter, pretty certain other is an inverter sadly I installed it in the main bedroom so not much use for heating the rest of the house!
Oh well it was just an idle thought.

If you have the pipework there, it should be an easy and relatively cheap job to upgrade - we got the TCL dual split from appliances direct. Ripped out the wifi modules and use the remotes for everything - I just don't trust anything that needs to connect to China for it to work... Anyway, it should be an easy swap-out, we've used it at -3 deg. C. ambient and it's warmed the house quickly from 16 deg. C., whilst the GCH has warmed up and took over the heating load (both are set to a max of 19.5 deg. C.) but the GCH does a better job of warming the fabric of the building whereas the aircon just provides warm air.

 

[Gareth J]

I didn't know about the DNO approval, thanks for the info.

If putting in below their 3.68 limit, it's more informing them rather than asking approval. There's a form; G-somethingorother

 

[Gareth J]

I've had a look on the website but don't really know what I'm looking for
Is 4kw a decent size for a family of 4?
We're on oil but I want to use solar to heat a cylinder of water as that is what costs the most, I figure we could have free hot water all summer.
I'll need a much bigger cylinder or heat store but don't know what way to go.
Any advice?

Regarding size of array and size of tank for your HW requirements, it's hard to advise with any accuracy. My experience, with a 4kw array and a 200l tank was that it would do the vast majority of our hot water usage through the summer. Two people showering once a day plus dishes etc. 4 adults? Probably not enough for that. I do remember having to boost when we had guests.

Regarding your tank size, you could, as an experiment, get your current tank as hot as possible with the boiler and then switch it all off - see how long it lasts before people moan about no hot water. Will give you an idea of scale of demand and therefore a sensible storage target too. If it helps get some idea of orders of magnitude, on the 4kW array, our diverter widget pushes ~1600kWh per year into the the HW tank. That might be very roughly equivalent to 150-200l of heating oil equivalent. (Over summer)

Cutting water heating by fossil fuels in summer is the easiest to achieve and has added advantages as it's when boilers are operating at their least efficient and when heat losses through the pipework/boiler network are of least use or even unhelpful, when the house is uncomfortably warm already.

 

[the snooper]

After reading this thread i'm guessing puffernutter is more confused then he was before he asked the question

 

[Domdom]

I had an interesting conversation with a French colleague about solar schemes in France.
So, over there, if you have a solar installation you are not allowed to use what you generate, it must be sold to the French national power company.
There was me ready to think the worst but, quelle surprise non!
You buy your electricity from the power company as normal, current price approx 15c per kw/h. Fair enough.
Then, the electricity you generate is all sold to the same power company, on a different meter and they pay you 4 times the buy price for it. Yep, 60c per kw/h.
Makes our feed in rates look a bit thin.

 

[dobbslc]

Regarding size of array and size of tank for your HW requirements, it's hard to advise with any accuracy. My experience, with a 4kw array and a 200l tank was that it would do the vast majority of our hot water usage through the summer. Two people showering once a day plus dishes etc. 4 adults? Probably not enough for that. I do remember having to boost when we had guests.

Regarding your tank size, you could, as an experiment, get your current tank as hot as possible with the boiler and then switch it all off - see how long it lasts before people moan about no hot water. Will give you an idea of scale of demand and therefore a sensible storage target too. If it helps get some idea of orders of magnitude, on the 4kW array, our diverter widget pushes ~1600kWh per year into the the HW tank. That might be very roughly equivalent to 150-200l of heating oil equivalent. (Over summer)

Cutting water heating by fossil fuels in summer is the easiest to achieve and has added advantages as it's when boilers are operating at their least efficient and when heat losses through the pipework/boiler network are of least use or even unhelpful, when the house is uncomfortably warm already.

Thanks! I know how long it takes for people start moaning about cold water! About 1 long showers worth
I only have a 120 litre cylinder atm but have beefed up the joists in the tank room to take a much bigger cylinder! Just don't know weather to go for solar thermal or PV.
PV seems more versatile.