Are solar panels on a new build worth it?

GreatApe

mmmmikey wrote: »

At the risk of confusing things, could I float a slightly different idea? Buy the battery first......

The established view on batteries is that they're something you buy to store spare energy from your solar panels, but that you can also use to store cheap off-rate electrcity if you're on an E7 tarriff. It's quite natural that the thinking on this forum is skewed towards that way of thinking because many of the folk here have solar panels already.

I am progressively reinforcing my view that it will become the norm to look at this very differently in the near future for new installations (i.e. where you don't already have panels).

My theory (expectation?) is that as smart meters get over their undoubtedly shaky start, more and more time of use tariffs will become available, and for many people buying a battery system to store electricity bought when it's cheap for use when it's expensive will be a winner, even without solar panels.

So if I moved to a house without solar panels or battery storage today, I'd probably either be looking to buy the battery system before the panels, using the Octopus Agile tariff (and keeping my fingers crossed that more similar tariffs follow suit and increase the competiton) or I'd hang on for a year and see what happens to tariffs.

I've posted this view here and there a couple of times and nobody has shot me down, but having said that I do recognise that it may be a bit too speculative for many.

This is a bad idea

At a cost of say £7,000 installed for a Tesla power wall and assuming a 20 year life (twice the 10 year guarantee so there is risk there!!) and 3% interest rate this will cost the owner £465 a year over its lifetime

My electricity bill is less than that

Also batteries are net electricity consumers
Let non batteries soak up any excess

Like 'wind heaters' which can be smart cheap resistance heaters installed in the hallway of a home
When there is excess marginal green generation these wind heaters can turn on to soak up the excess thus saving natural gas as the property boiler works less hard burning less gas to maintain property temperature. This is also a roughly 125% efficient use of electricity as 1 unit of electricity will displace roughly 1.25 units of natural gas in this application.

Better than millions of batteries causing pollution in their manufacture and ultimate disposal and using more electricity in their internal losses

mmmmikey

GreatApe wrote: »

This is a bad idea
.......
My electricity bill is less than that

Time will tell. It's actually nearly working for me now on my current E7 tariff with payback expected in the order of 12 years if things stay the same. It hinges to a large degree on the difference in cost between peak and off peak rates and we're not far enough into time of use tariffs to make a judgement based on data.

On the point about your electricty bill, clearly you can't save more than you're spending so anything you do decide to do needs to factor in your own circumstances. I suspect that for low users battery systems may never be worth it, and whatever your usage level you need to buy something of an appropriate scale. The Tesla PowerWall is a reasonable option in terms of cost per kWh but it's also quite a large capacity device and not a good buy if you're not able to take advantage of the capacity. There are plenty of options at half the price with half the capacity.

Solarchaser

Tbh I think you struggle to make batteries worth it without solar, just basing it on difference of tariffs.... at the moment.
If the "normal" tariffs increase, then yeah, but my normal tariff at the moment is 13p, and the off peak I'm likely to go onto is 5p, so only 8p of a difference, and at let's say 90% efficiency of battery storage, closer to 7p.

A powerwall is £7k plus installation at £1-2k, for 13.5kwh so theres definitely cheaper per kwh out there.
Around 20kwh for the same price for lux parallel inverters.

Hexane

Just an additional note, which had not occurred to me before. A property having a very good EPC rating is not a reason to discount solar PV as a way of saving money. The EPC rating mostly (not entirely) considers the efficiency of space heating, so for example insulation features highly and heating controls of different sorts feature highly. Although some on this forum have had success combining solar PV with heat pump technology for space heating, the major gains from solar PV are more usually concentrated, as others have said, in high consumption items such as dishwashers, washing machines, tumble driers, and potentially one day battery electric vehicles. (With "free" domestic hot water heating as a side benefit in some cases). So the benefits of solar PV are mostly separate from, and in addition to, a good EPC rating... even though EPC documents sometimes mention solar PV.

Reed_Richards

GreatApe wrote: »

So if you are a household where £5k isn't going to change you life then just get solar panels and don't worry or even calculate the returns

GreatApe wrote: »

This is a bad idea

At a cost of say £7,000 installed for a Tesla power wall and assuming a 20 year life (twice the 10 year guarantee so there is risk there!!) and 3% interest rate this will cost the owner £465 a year over its lifetime

This is hardly a consistent approach; devil-may-care about solar panels and all about hard cash when it comes to a battery. I wonder if the inconsistency comes about because GreatApe just likes to adopt a contrarian stance?

The UK does not have enough storage capacity for electricity generated overnight and it you add some more yourself that's every bit a "green" as adding solar panels, possibly more-so. What's more you can get a subsidised battery for a good deal less than £7,000 ( https://www.edfenergy.com/for-home/battery-storage ) whilst you would be hard-pressed to find an investment that could guarantee a 3% return.

JJB51

Thanks guys some great info to think about.


Given someone is always generally home I think the price for the batteries is probably not worthwhile at this stage. It might be something i go back to at some point.



I will shop around and see what prices I get quoted for a solar set up. Is there any decent national companies that I can look at? I have bad experiences going through local unknown companies!


Thanks again !

Hexane

Jbennett51 wrote: »

I will shop around and see what prices I get quoted for a solar set up. Is there any decent national companies that I can look at? I have bad experiences going through local unknown companies!

I had a good experience going through a local unknown company In general, always look to get three separate quotes from three different companies. (And if you mention here what the quotes propose and what they cost, we can offer lots of feedback.) Regarding national companies, I believe the consensus of this board is that Project Solar is one to avoid.

GreatApe

Reed_Richards wrote: »

This is hardly a consistent approach; devil-may-care about solar panels and all about hard cash when it comes to a battery. I wonder if the inconsistency comes about because GreatApe just likes to adopt a contrarian stance?

The UK does not have enough storage capacity for electricity generated overnight and it you add some more yourself that's every bit a "green" as adding solar panels, possibly more-so. What's more you can get a subsidised battery for a good deal less than £7,000 ( https://www.edfenergy.com/for-home/battery-storage ) whilst you would be hard-pressed to find an investment that could guarantee a 3% return.

I should be clearer

Spend any amount of money if it's purely because you want to
Buy solar PV buy batteries buy a puppy buy a iguana buy an expensive car and keep it in the garage just to admire it....whatever makes you happy. If you have the spare money and at least about 20% of households probably do then I encourage you to do what makes you happy

But if it's on a purely economic decision.
You don't really care about the thing your only doing it to save/make money then batteries make no sense and solar is marginal probably not a great idea but better than batteries

GreatApe

mmmmikey wrote: »

Time will tell. It's actually nearly working for me now on my current E7 tariff with payback expected in the order of 12 years if things stay the same. It hinges to a large degree on the difference in cost between peak and off peak rates and we're not far enough into time of use tariffs to make a judgement based on data.

On the point about your electricty bill, clearly you can't save more than you're spending so anything you do decide to do needs to factor in your own circumstances. I suspect that for low users battery systems may never be worth it, and whatever your usage level you need to buy something of an appropriate scale. The Tesla PowerWall is a reasonable option in terms of cost per kWh but it's also quite a large capacity device and not a good buy if you're not able to take advantage of the capacity. There are plenty of options at half the price with half the capacity.

Some things to consider

If batteries got cheap enough then utilities would install them on a large scale which would close the gap between on and off peak rates

Likewise if BEVs become popular then there won't really be a night time or off peak rate the BEVs will soak up those times.

With the two interconntors to Norway due to come online 2021 & 2023 iirc that is a huge 2.8GW of demand for low priced power from them. For instance they may import at full capacity when prices fall to below £25/MWh and export at full power when prices are above £40/MWh. So those two links alone will soak up a massive upto 2.8 GW of cheap electricity. And ideally we will build at least one more link to Norway

Also all but one UK nuclear reactor is closing over the next 7-8 years That is about 6GW going offline
Those reactors reduce night time prices more than they reduce day time prices for the obvious fact that they are about 30% of night time supply and closer to 15% of day time supply.
So when the reactors shut that means it's less likely to be a cheaper night time rate especially coupled with all of the above factors too


If the Scots build their big hydro project (1.5 GW power 30GWH energy) that's another source competing for this cheap rate electricity. It would mostly be night time demand , day time supply


So in short expect Norway links and the new Scottish pumped hydro to be daytime supply night time demand. Expect the closure of nukes to mean less daytime supply but much less night time supply. These factors will likely mean wholesale prices are not as low during the night as they currently are.

Anyway it's more effort than its worth
People should buy if it's their hobby irrespective of return rates
People should avoid if they feel it's purely a good investment return

GreatApe

Plus why buy a small battery for £7k or whatever when you can buy a much bigger battery on wheels for £22.5k you displace oil the most expensive fossil fuel. You can still charge up when it's cheap and perhaps in future use this battery on wheels to supply the house during peak rate times