For help, advice and discussion about stuff not related to aviation. Play nice: no religion, no politics and no axe grinding please.
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By Dodo
FLYER Club Member  FLYER Club Member
#1907186
I am probably about to take the plunge into a solar power and solar battery installation for various reasons including a desire to reduce my carbon footprint, take advantage of the zero rate VAT whilst it lasts, provide a bit of security for power outages, and, in the very long term, perhaps get my money back with reduced electric bills. We don't yet have an electric car but next car will almost certainly be electric.

We are in the south of the UK with a big south facing roof.

Has anyone had any good, or bad, experiences they are willing to share? I'm particularly interested in things that you hadn't thought about before installation, that you wished you had considered, and also any experiences of selling a house with a solar installation. Was it a selling point or a problem?

Thanks all.
#1907190
I’ve got 50kw solar and 21kwh batteries. I love it but wish the batteries were bigger. I’m happy to chat and give any info you like.

I’m in the country, heated entirely by heat pump. The solar panels are way too big in the summer and way to small in the winter.
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#1907191
Dodo,

My panels are over 10 years old now, and they have given no trouble at all. They are a 4kw system and have generated on average about 3800 kwh per year.

I haven’t gone for batteries as yet. They are still expensive, and the big issue with solar from a storage perspective is you generate far and away the most energy from April to September when electricity usage is generally the lowest, and generate far less from October to March when usage is highest. From a cost / benefit standpoint, you probably would get a better financial result from a few relatively low cost smart switches for your hot water and car when you get it that will make good use of your generation. The additional benefits from batteries will probably be marginal once that is taken into account.

I've just done a quick calculation. My generation by quarter has been:

Q1 16%.
Q2 38%
Q3 34%
Q4 12%.

Colonel Panic has a battery setup. I'm sure he can advise better on that side of things, but as for the panels, I'd say go for it.

Regarding selling, any smart buyer will probably see them as a plus, but they can give mortgage issues. I wouldn't bother if you were planning on moving anytime soon. They are probably best seen as a good long term project.

Paul.
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#1907196
It's imperative that you get a battery in the UK as I understand from @colonel panic that you get money for feeding in on the assumption that you will feed in half of your generative capacity!

We have solar panels (pre-requisite from Mrs FD to allow me to buy an EV!) and with the 7.5kWh battery we are providing with that set up about a third of our electric we needed (including EV) comes from our roof.

Because we are near a conservation area we needed to put the panels in the roof rather than on a rack on them - was not very much more expensive and looks a ton better.

With prices going the way they are they are a good investment, if for nothing else because it makes you feel good. If you want it to work when you have a power outage, some additional bits need to be installed.
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#1907200
Flyin'Dutch' wrote:It's imperative that you get a battery in the UK as I understand from @colonel panic that you get money for feeding in on the assumption that you will feed in half of your generative capacity!



I'm not sure that is correct any more FD. The feed in tariffs were dropped in 2019.

https://energysavingtrust.org.uk/grants ... in-tariff/

Earlier installations received an export payment that assumed, in the absence of a specific export meter, that 50% of electricity generated would be used and 50% fed back into the grid. This was so even if you had a battery set up that meant you used 100% of the electricity you generated and actually nothing was fed back to the grid.

Even then, the export payment is minimal so doesn't really figure significantly in the economic calculations.

Without a doubt, current price rises mean it makes sense to be able to use as much of your generation as possible and are swinging the numbers in favour of battery set ups, but the thing is you can get much of the bang for your buck from cheap smart switches, and the remaining benefits of the battery set up should be viewed from a marginal benefit viewpoint.

It would be different if you could store everything you generate until you need it, but the seasonal difference of generation and usage would require a massive - and therefore expensive - battery. Even then , battery loss merely due to time would have a major impact.
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#1907203
Paultheparaglider wrote:I'm not sure that is correct any more FD. The feed in tariffs were dropped in 2019.
.



Cheers PtPG!

My brother in the NL was an early adopter and the deal at the time was that anything you fed in was 'paid' at the price of the cost of a kWh when buying, basically making the Grid your battery.

Those days have gone there too.
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#1907205
I'm probably 12 months from buying, so speaking from research rather than experience. However, my sense is the battery debate comes down to your day time usage.
We're likely to be out all day and use electricity early morning for heating; and evening for cooking/heating/car charging etc, We've probably got space for 6kWp of panels therefore I think we would benefit from a battery. If I'd only got 3kWp of panels and planned on having meaningful daytime usage then the battery might be unnecessary (albeit it will hopefully let me get rid of the generator for the power cuts).

As an aside, there is a 49.99MW solar farm going in on the edge of our village. That will feed shipping containers full of batteries which will then feed the grid when the price is right rather than when the sun shines. I don't know if this is the normal model or an exception.
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#1907206
We have a 4kW set up in the paddock. Got in on the 22p tariff. We also fitted a Solar Boost which is basically a shunt - it detects outflow to the grid and turns the immersion heater on. Simple and cheap.

They are not having any of my electron ergs...... :pirat:
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#1907215
Dodo,

Whichever system you ultimately select make sure it can move thru' two axes. For example: if your system is static eg. cannot follow the Sun's path particularly as it moves at 15 degrees per hour from East to West you will not get full benefit from your panels.

The difference is about 20% available to you from a single axis installation to about 40% available conversion of solar energy from a two axis installation. Heaven alone knows, altho' some bright spark (pun intended) perhaps can work it out at which point in the future you get your investment back and go into profit, by which time, probably, your panels need to be renewed !
Dodo liked this
#1907225
Iff you have a Tesla Powerwall and a smart meter, Octopus Energy offer the Tesla Energy Plan where they "take control" of your battery and use it to minimise the evening peak load on the grid. In return for cycling your battery quite deeply every day, they give you a tariff of ~11p/kWh and 22p/day (it varies slightly with where you are in the country) on both import and, critically, export - a so-called "symmetric" tariff. This effectively turns the grid into an infinite capacity, 100% efficient battery for any excess solar you can't use today but might need in, say, six months' time. There is a hidden cost of about 1kWh/day losses through the Powerwall, but you'd probably be paying most of that anyway. Having more than one Powerwall makes very little sense as you end up paying that 1kWh/day loss on each Powerwall, however having more solar makes a whole lot of sense.

If you have a Tesla Gateway too, you get to keep a minimum charge of 20% in the Powerwall (automatically increased to 100% during predicted storms) to handle power cuts, and the Powerwall will also allow your solar to operate during a power cut: most "grid tied" solar systems have to shutdown during outages for safety, which many owners don't realise.

Financially you can probably do slightly better using a Time of Use tariff like Octopus Go to charge the Powerwall overnight and to "go off grid" during the peak hours, but from an environmental point of view, helping the National Grid to avoid firing up a CCGT power station at 1600 every afternoon is probably more beneficial and still saves you some money.

My setup has 4.5kWp of solar, a single Powerwall and Gateway, and a Zappi car charger for my Hyundai Kona EV. I'm very happy to discuss more details and (if you're able to get to Redhill Aerodrome) show anyone around my setup. I've only had the solar since June 2021, and in about 9 months it has generated 3.3MWh against a household consumption of around 4.2MWh (~80%) including car charging, and we still haven't experienced the best months of the year for solar in the UK.
Colonel Panic, rikur_, Dodo and 1 others liked this
#1907230
We are 7 to 8 years in to having had a 4kW PV system installed, and have loved every minute. Our Feed In Tariff assumes that we will export 50% of what we generate, whether we do or don't; until we added the Powerwall battery we self consumed 50%, shoved 25% in to the HW tank via a Solar iBoost widget and exported the remaining 25%. #bummer. We've had a 13kWh Powerwall for 2 years now, and have managed to get exports down to perhaps 5%.

As others have said, balancing the system to match your usage is quite important; there is little point in me putting in more PV generation as for much of the year all I would do is export the additional generation (for no return). Generation levels vary _hugely_ over the seasons.

Since installing the battery we have been able to run the house ~90% using only cheap rate import / self generation, and with the recent rises in kWh prices the maths are even better than before. The other benefit of having a battery is that should there be a power cut you can still generate AND use your PV panels; without a battery the PV _must_ click off. Again, #bummer.

@Dodo - you would be most welcome to pop up anytime and I can show you what we have - I'm near Haywards Heath.
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#1907264
Flyin'Dutch' wrote:
Trent772 wrote:My problem is we are an all electric household - off gas grid, ditched oil a while ago. We consume 25,000kWh per year.


WOW - and that is sans EV?

:shock: :shock:

Air source/Ground source heating not an option?



That is our total consumption and includes whatever benefit we get from EV.

We have no wet central heating and as our house dates back to 1800, although essential rebuilt in 1975 to modern code, I am too old to start messing around - the storage heaters work really well, I study Carol every morning - :wink: - and twiddle the settings accordingly.

Aga uses a lot, but we have no heating in the kitchen otherwise.

I used to pay £300 a month for all my energy, will now be around £550
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