Solar panels - or not?

[[XAP]Bob]

Looking into the future the demand curve could shift as overnight charging of electric vehicles picks up. This is likely to curtail cheaper overnight tariff's and lead to a flatter tariff structure.

It will lead to a more dynamic market, not a flat tariff structure. You want to incentivise people to use electricity when it's basically free, and disincentivise them from using it when it's expensive.
We plug the car in most times when we get home, and Octopus decides when to charge it, though I decide how much, and when by. I have the car charger monitored, and when it's charging the car I kick the home battery to force charge as well... because all of my usage at that time is at 7p, so I top up as much as I can.

[Cugel]

Incidentally, the home batteries mean we download 6.5p per kwh e-juice at night for use the next day. As day rate is 24p per kwh that saves us 18p per kwh.

That’s a nice saving; I wonder how long it’d take to pay back the installation costs of a battery only system that had enough storage capacity to see someone through for say a few days. Additional solar panels might cost in, but do they cost in when buying eleci at 6.5p per KWh?

To an extent I suppose the questions are: what’s available as storage batteries; what do they cost; and what’s their likely life?

There's a lot of options for storage batteries, although to use any you'll also need an inverter to change AC<>DC and voltage.

New house batteries tend to be the most expensive. Those made with previously used cells (e.g. from now-scrapped cars) cost less but performance is not as good and guarantee is shorter (typically 3 rather than 10 years to retain at least 80% of when-new capacity). In practice, they'll probably last as long as solar panels (20 - 25 years) - but with an ever-reducing capacity, perhaps down to 30% of their original capacity.

Perhaps the least expensive battery option is to buy an e-car with V2H capability, as the car battery can be the house battery when its parked on the drive. You'd effectively getting an e-car for half-price, as using its battery as a house battery too means that you don't have to buy a house battery.

But you still need an inverter (a charger/inverter for use with a car battery).

V2H isn't very mature, so there aren't many e-cars that support it and not many inverters to use it with the house. But it may be the coming thing.

Of course, you can't use the car battery as a house battery when the car is driving about unconnected to the house charger/inverter. A retired or home-working owner might see the car on the drive 22 hours each day. But a commuter would generally only have the car connected to the home from, say, 6pm to 7am. Also, you'd need to juggle the car battery charge level carefully, to ensure the house doesn't drain it if you have to go somewhere the next day.

***************
Personally I'd like to see local sub-stations that contain large shareable battery storage, so that several households could draw from them after they fill each night with cheap rate e-juice, as well as with daytime free e-juice from the solar arrays built atop of them; and from excess individual household solar production during the long sunny days.

But that would take a government (national & local) not wedded to large power station builds and a huge grid capacity to distribute the power. There's too many vested interests that prefer building things like nuclear or huge windfarms, as these generate Big Profits. If e-juice production and use was organised more like the interweb, including millions of local producers using rooftop solar and windmills (when small ones become efficient) with local battery storage, it would all be less expensive for consumers (long term) and far, far more resilient to damage or attack.

[pete75]

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FIT payments are no longer a thing, but you can, and should, get an export tariff, and a time of day tariff of some sort.

Yes they are, I've recently had one.

Not for anyone new... which was the point of the thread.
I've actually just taken one house off their deemed export payments in favour of SEG.

They've stopped FIT for new installations?

[RickH]

Perhaps the least expensive battery option is to buy an e-car with V2H capability, as the car battery can be the house battery when its parked on the drive. You'd effectively getting an e-car for half-price, as using its battery as a house battery too means that you don't have to buy a house battery.

An interesting variation I came across on social media recently was an account of someone in Ireland who had their aging batteries in an oldish Nissan Leaf replaced & the old ones repurposed as a home battery system. Greatly increased range for the car & a larger than normal home battery. I think the total cost was around €5-6k.

[[XAP]Bob]

They've stopped FIT for new installations?

Back in 2019.

But the rates you can get for export via the SEG make up for that - I get paid 15p/kWh export.

That's a healthy rate, well below the market value most of the time, but still healthy. My array is only small (only 2.4kWp), but it still generates a little over 2MWh a year, and this year I've exported fractionally over 100% of the energy it's generated - which means I've basically lived off the (9.5kWh) battery - just 1.5% of my usage has been at peak rate (and a third of that is on days with demand flexibility sessions).
Whilst I don't use electricity for heat (except in one room), we both work from home, as well as having two kids - so we are a fairly high usage household - with a total cost this year (to the end of the 11th) of £587.
Bearing in mind that that includes ~12,000 miles of fuel for the EV, which in previous years would have cost well over £2,000 in diesel.

[[XAP]Bob]

Perhaps the least expensive battery option is to buy an e-car with V2H capability, as the car battery can be the house battery when its parked on the drive. You'd effectively getting an e-car for half-price, as using its battery as a house battery too means that you don't have to buy a house battery.

Challenging - because at the moment you can only do that with chademo, so you're mostly limited to Nissan, and the V2H chargers are absurdly expensive... you could get an AIO from GivEnergy for the prices I've seen them at.

Batteries are zero rated for VAT at the moment, even without a solar installation.

[Biospace]

So I can't decide wether to go ahead or not - any thoughts?

We went ahead around 20 years ago, it was largely a self-installation which was very satisfying. The number of panels grew and the addition of some battery storage resulted in a very flexible system, to the extent that had a permanent back-up generator been used for the darkest weeks of the year we could have said cheerio to the electricity bills. This generator would have run on renewable energy, but as there was a house move looming, we held off.

Prices today have reduced to close to "no-brainer" territory but there are still many considerations such as condition of the roof, any local planning constraints (although today these rarely present a big problem), size of installation and if the pitch of roof is sufficiently well-suited to orientation. East-West installs generally exceed expectations - clearer air in particular in the morning for more polluted parts, less heat build up (which results in loss of panel efficiencies) and the potential for clearer skies.

Financially, solar PV has made more sense as panel price has fallen and Grid electricity costs have risen but it shouldn't necessarily be the only motivator, I've seen some disappointed people. Instead, help them create a more flexible energy supply - as houses and their occupants grow ever less capable of functioning without electrical power, having your own energy stores grows in importance. Remember even mobile internet can vanish in a sustained outage, that gas boilers won't work (nor heat pumps!) - typically power outages are mid-Winter.

[Biospace]

Perhaps the least expensive battery option is to buy an e-car with V2H capability, as the car battery can be the house battery when its parked on the drive. You'd effectively getting an e-car for half-price, as using its battery as a house battery too means that you don't have to buy a house battery.

Challenging - because at the moment you can only do that with chademo, so you're mostly limited to Nissan, and the V2H chargers are absurdly expensive... you could get an AIO from GivEnergy for the prices I've seen them at.

Batteries are zero rated for VAT at the moment, even without a solar installation.

Aren't there quite a few BEVs which will supply 1kW or so continuous, not as V2H (which involves much more than just the vehicle) but to isolated devices? With a little extra wiring, this could easily be organised to light the home, power the router, laptops and even run a boiler and central heating pump.

After our electric was cut during the recent storms I had an inspirational flash. If I had a 12v battery to hand I could have powered up the internet router and Swmbo could entertain herself watching strictly on her iPad.
Is this feasible?
Reported this morning, homes down in Somerset are still waiting to be reconnected, 5 days after the storm.

Lighting, router, laptops, smaller tv screens, charging for mobile devices, even a gas boiler and CH circulation pump use little energy. A couple of decent size 12v batteries (one of which can be taken from a car, search motorhome forums for recommendations) can offer several hours' supply of 250w continuous. Lighting, router and laptop for considerably longer. Pure Sine Wave inverters rather than the cheaper variety are needed for some applications - but lighting, laptops and routers will generally be fine on the cheap inverters.

[PDQ Mobile]

They've stopped FIT for new installations?

Back in 2019.

But the rates you can get for export via the SEG make up for that - I get paid 15p/kWh export.

That's a healthy rate, well below the market value most of the time, but still healthy. My array is only small (only 2.4kWp), but it still generates a little over 2MWh a year, and this year I've exported fractionally over 100% of the energy it's generated - which means I've basically lived off the (9.5kWh) battery - just 1.5% of my usage has been at peak rate (and a third of that is on days with demand flexibility sessions).
Whilst I don't use electricity for heat (except in one room), we both work from home, as well as having two kids - so we are a fairly high usage household - with a total cost this year (to the end of the 11th) of £587.
Bearing in mind that that includes ~12,000 miles of fuel for the EV, which in previous years would have cost well over £2,000 in diesel.

Let me get this right?
You have a 2.4 kw (peak) solar installation.

And from that you run a multi person household using fairly modest leccy consumption but not super low.
But you also travel 12000 miles by BEV all from the same panels?
But have an annual leccy bill of under £600??
Standing charge included?

Could I surmise you use almost all the solar export monies to buy off peak mains leccy?

[SporranMcDonald]

The strange thing about telling anyone about my Net-Zero-Carbon home and the intention to leave a survivable world for the next generations is . . . . . . . .

Within the first two sentences of the response the whole thing will be converted into money values !! . . . and never return to mentioning environmental destruction.

One might think that a survivable world is the overwhelming priority.
One might think that an economic system that externalises / ignores environmental damage would be a cause for concern.

[Cugel]

The strange thing about telling anyone about my Net-Zero-Carbon home and the intention to leave a survivable world for the next generations is . . . . . . . .

Within the first two sentences of the response the whole thing will be converted into money values !! . . . and never return to mentioning environmental destruction.

One might think that a survivable world is the overwhelming priority.
One might think that an economic system that externalises / ignores environmental damage would be a cause for concern.

Aye! It astonishes me that the vast majority of the population seem more concerned about having their two foreign holidays a year and plenty of steaks & burgers rather than give them up in the hope that their children might not become boiled frogs.

On the other hand, they may be right to assume that no matter what any of us individuals do, the race to the climate change cusp will continue, nay accelerate, until over we all go into utter chaos full of heat, wind, deluge, food shortages and all the rest.

Mind, I still indulge in consumables and behaviours that contribute my little bit to global warming. I might generate more e-juice than I use, buy no oily-fuel myself, never fly and give up all but a few sausages a month in the way of meat but ..... I'm a chocoholic; and a coffee addict; and inclined to buy things (mostly tools) that come in plastic packaging, probably from China or perhaps Sweden, in an oil0guzzlin' ship. .......

So ... me solar & batteries and e-car and all that are just empty gestures, as far as climate change is concerned. And anyway, the primary reason for doing all that solar et al was economic. It saves thousands every year and seems a far better "investment" than a load of stocks & shares that just sit there sucking the wages out of the working folk that actually give them value, then are fought over by the kids when you die.

[[XAP]Bob]

Let me get this right?
You have a 2.4 kw (peak) solar installation.

And from that you run a multi person household using fairly modest leccy consumption but not super low.
But you also travel 12000 miles by BEV all from the same panels?
But have an annual leccy bill of under £600??
Standing charge included?

Could I surmise you use almost all the solar export monies to buy off peak mains leccy?

Yes, standing charge included - and I wouldn’t say we were modest users, we’re well above average. (2.4 people, 2.7MWh)
Between export of solar, and using a good time of day tariff… yes, my electricity bill is that low.
I take full advantage of the DFS schemes etc whenever I can.

So far this year, which has been awful for solar, (346 days): 9667 imported, 1886 generated, 1916 exported, 3446 EV charging (i.e. 3.5m/kWh). £587 (£1.70/day, 6.1p/kWh all inc SC)

Payback period for the installation is looking a little under six years (assuming I’d still get 22.6p without the extra gear), and it was mostly financed with a 5 year loan at what now looks like very attractive rates (same as my ten year fixed mortgage, expiring a few years hence).


For the environmentally conscious… I record import against the national grid stats (well home assistant does that for me) and of the 9.7MWh imported 6.7MWh have been low carbon sources (and I exported 1.9MWh, leaving only about 1.1MWh of truly dirty electricity *net* imported). That’s because the cheapest power comes when the grid is cleanest…

I do need to upgrade to a heat pump, and plan on doing so, that will require additional storage to maintain my current very low rates though.

I don’t think these things are empty gestures… they are not a complete solution, but they are part of the answer. And a part which also makes economic sense.

I’ve not flown anywhere (other than for work) in years - did take the train to Spain a couple of years ago for an early sun holiday - but we tend to holiday in the UK.

[pete75]

The strange thing about telling anyone about my Net-Zero-Carbon home and the intention to leave a survivable world for the next generations is . . . . . . . .

Within the first two sentences of the response the whole thing will be converted into money values !! . . . and never return to mentioning environmental destruction.

One might think that a survivable world is the overwhelming priority.
One might think that an economic system that externalises / ignores environmental damage would be a cause for concern.

You're kidding yourself if you think what you're doing will make any discernable difference to the amount of environmnetal damage happening now and in the future. If it makes you feel good about yourself - carry on.


The only way anything effective will happen is if most people introduce low/no carbon features to their houses. That will only happen if it's proven to be financially beneficial, hence the focus on the economics of solar panels.

[Cugel]

Perhaps the least expensive battery option is to buy an e-car with V2H capability, as the car battery can be the house battery when its parked on the drive. You'd effectively getting an e-car for half-price, as using its battery as a house battery too means that you don't have to buy a house battery.

Challenging - because at the moment you can only do that with chademo, so you're mostly limited to Nissan, and the V2H chargers are absurdly expensive... you could get an AIO from GivEnergy for the prices I've seen them at.

Batteries are zero rated for VAT at the moment, even without a solar installation.

Yes, the somewhat specialised inverter/chargers needed for V2H seem to be offered at ridiculously high prices; and are few at present. Yet the benefits of V2H seem, potentially, large in an e-car flooded world so perhaps there'll be "price corrections" before long? We can only hope.

Perhaps that Miliband could cancel the ridiculous carbon capture subsidies in favour of stimulating and supporting V2H inverters of a wide capability, possibly including subsidies to buyers? He's already yapping about putting up solar panels all over the place (warehouse roofs and on any new-build) so who knows?

The advantage of subsidising solar, inverters, batteries et al for individual households (and perhaps businesses) is that a highly distributed yet also localised e-production and distribution facility could be build with far less expense than nuclear power stations and similar, with householders and businesses providing a goodly portion of the costs.

If enough storage capacity is included by way of not just household, car and business premises batteries but also thousands of local sub-station batteries and large facilities such as those that pump water up and down to/from very large water-bodies (via turbines) there might be so need for nuclear, gas or other damaging and expensive facilities to support the low solar and wind production periods. Add in tidal-flow generation (which is predictable and regular) as a further always-there generator and ......

[PDQ Mobile]

Let me get this right?
You have a 2.4 kw (peak) solar installation.

And from that you run a multi person household using fairly modest leccy consumption but not super low.
But you also travel 12000 miles by BEV all from the same panels?
But have an annual leccy bill of under £600??
Standing charge included?

Could I surmise you use almost all the solar export monies to buy off peak mains leccy?

Yes, standing charge included - and I wouldn’t say we were modest users, we’re well above average. (2.4 people, 2.7MWh)
Between export of solar, and using a good time of day tariff… yes, my electricity bill is that low.
I take full advantage of the DFS schemes etc whenever I can.

So far this year, which has been awful for solar, (346 days): 9667 imported, 1886 generated, 1916 exported, 3446 EV charging (i.e. 3.5m/kWh). £587 (£1.70/day, 6.1p/kWh all inc SC)

Payback period for the installation is looking a little under six years (assuming I’d still get 22.6p without the extra gear), and it was mostly financed with a 5 year loan at what now looks like very attractive rates (same as my ten year fixed mortgage, expiring a few years hence).


For the environmentally conscious… I record import against the national grid stats (well home assistant does that for me) and of the 9.7MWh imported 6.7MWh have been low carbon sources (and I exported 1.9MWh, leaving only about 1.1MWh of truly dirty electricity *net* imported). That’s because the cheapest power comes when the grid is cleanest…

I do need to upgrade to a heat pump, and plan on doing so, that will require additional storage to maintain my current very low rates though.

I don’t think these things are empty gestures… they are not a complete solution, but they are part of the answer. And a part which also makes economic sense.

I’ve not flown anywhere (other than for work) in years - did take the train to Spain a couple of years ago for an early sun holiday - but we tend to holiday in the UK.

Thanks for detailed reply.
I have never suggested "these things" are empty gestures.
I am glad it works for you.

Issues that I do have are that you don't really export anything, but simply consume! (2.4 kw not enough)
The payback time scale is dependent on you buying cheap off-peak and reselling at a profit I imagine?
(I do have a problem with that as I consider it pushes up costs for other standard tariff low consumption houses.)

I don't see nuclear as particularly clean, but rather as a necessary evil.

And around 50% of the grid isn't carbon neutral still- I don't buy into green tariff stories- if you get it from the grid you get the same proportion CO2 as everybody else.

...........
I would be interested in total cost (just ball park) for the whole show though.
Car, panels, battery and all the necessary clever management technology.
One day.....
........
It looks as if the Govt is going to force the leccy companies to offer a "no standing charge" tariff option.
The devil will be in the detail of course, but if really low consumption houses don't get some small benefit then it will be just so much more hot air.
We shall see.

I am not holier than thou.
I consume more fossil energy than I should.
The house is very good, but transport is fossil fuel.
I still cycle as much as I can though.
The last two months for example, have seen very low car miles and fuel consumption, perhaps 20 litres.