Reply With QuoteOriginally Posted by Barryboy
Well two quotes, actually, which worked out to within a couple of hundred pounds of each other.
The one which I prefer (simply because the rep was more knowledgeable, personable and patient with me under questioning) came in an £12400 for 10 panels (including birdwrap) giving a 4.5kw system, with a solis mini hybrid inverter and a Purestorage 5kwh battery. I have lots of technical info here which is frankly beyond me but that's the gist of it. They are also a local company who have been trading for more than 20 years. I know that £12K sounds like a lot but it's a long term investment in my home, and the money I have saved is earning the square root of bugger all in interest. I'm pushing 70 now and a good lottery win aside I can't envisage ever moving house. I'm worried that we'll never see cheap electricity again and the more I think about it the more I think I ought to go into solar and I can do it for the price of a good Rolex Sub.
Any thoughts, anyone?
Rob
Its very hard to comment without knowing how much electricity you use and what you may use in the future (Electric car for example).
I've not seen many examples where battery storage makes sense financially and I would say you probably aren't going to end up much ahead overall. On the other hand electricity prices might be an issue for a long while yet and the payback period then starts to drop.
To add I have solar panels myself which i think are amazing because 1) I'm on the old FIT and 2) I didn't pay for them. Given that when I looked at adding batteries it still didn't make much sense.
Last edited by Rob s; 27th January 2023 at 13:14.
Do you get much sun in wales?
sorry, not helpful but couldn't resist. Its rained every time i've been to newport.
That's a hell of a lot of money to shell out. What's the estimate for it paying for itself and then actually benefitting your pocket?
This. A 5KW system won't power a 7KW charger as an example, let alone 11 - 22KW rapid chargers (which is where the market is heading). That's not to say a 5KW system won't be useful, just that you would always need at least some grid supplied electricity to charge. If you don't see an EV in your future and simply want to be able to be 'off grid' for some of your energy needs it makes sense.
I did it last year before E prices jumped & systems were cheaper before the crazy demand.
Sounds similar set up to me I’m 5.2 kWh system with Solis inverter & Puredrive battery.
Is your quote hybrid Solis & DC Puredrive or AC?
My ROI was 8 years but when the E jumped to 34p that dropped to 6.
Even this week we have seen days with 100% battery & wfh washer, dryer, dishwasher etc all been used multiple times.
IF you can use what you produce they can workout for you but giving it away back to the grid is pointless. Buying in at 34p selling unused 5p depending on tariff.
My AP shows I have used in the past seven months,
From grid 861 kWh
From battery 965 kWh
From Solar 2363 kWh
Fifth of pie chart basically.
Just about everything you’ve said there is wrong.
Well at least tell him why!
11-22kw rapid chargers in domestic settings?
The 5kw mentioned by the OP was actually A 5kwhr storage battery being charged by a 4.5kw solar panel array.
The storage battery can charge an EV battery but only by a maximum of 5kwhr which will be pretty useless for an EV battery (probably 60+kwhr). It could charge at 7kw though, until depleted. The EV could however, be charged from the 4.5kw solar array at a maximum of 4.5kw if the EV has a 7kw charger, or 3.3kw if it only has a 3.3kw onboard charger.
11 or 22 kw chargers require a three phase supply so unlikely to ever become commonplace in the UK as almost every domestic property only has a single phase supply.
Is that better Mick?
Last edited by Dave+63; 27th January 2023 at 15:22.
No worries, I'm not claiming to be an expert here. I assumed that OP's Microgen and storage system would power an AC/DC EVCP. Always keen to be educated, so would appreciate understanding the math's behind a 5KWH battery unilaterally enabling an AC/DC EVCP to output 7KWH.
Whilst 11/22KW AC/DC chargers require a polyphase supply DC/DC chargers do not.
Not currently, but viable and a roadmap item for some EVCP manufacturers. The key being evolution of battery storage systems and battery chemistry i.e LTO/NTO. Once battery systems evolve to provide required energy density, and rapid charge / discharge capabilities viability increases. In fact GOVT have recently awarded some innovation funds to look at exactly this. I know, because it's me spending their money.
Then we get into Demand Side Response, Virtual Power plants and Grid flexibility. Once those are solved and domestic battery systems become ubiquitous and a constituent element of wider VPP's and remotely load controlled in real time by DSO's, in my view (others are available) that will be the end of AC/DC charging and it's constraints.
Edit: it’s not outputting 7KWH, it’s outputting 7kw.
Imagine it as fuel; a 1 gallon tank of fuel can still power a motor that consumes 2 gallons per hour, but only for half an hour.
It’s the same principle, a 5kwhr battery can provide 5kw of energy for an hour or 10kw for half an hour.
5kwhr = 10kw x 0.5hr
5 gallon = 10 gallon/hr x 0.5hr
The 4.5kw from the solar array charging a 60kwhr battery is equivalent to a 4.5 gallon/hr pump filling a 60 gallon tank. It does it, just slowly.
Last edited by Dave+63; 27th January 2023 at 16:43.
Thanks, appreciate the clarification.
I assumed an AC/DC charger in the way and consequently an inverter and associated efficiency loss, so hadn't applied the maths detailed above and further assumed that the maths would in fact vary on a per installation basis depending on what inverter was in use and it's efficiency characteristics / loss.
How much is your current leccy bill?
If I'm paying £130 per month for a four bed house with 2 adults and 2 kids using all manner of devices and appliances, and me working from home using a computer and monitor 3-4 days a week, you must be paying less, unless you have no gas supply so 100% leccy? Let's assume £100 per month or £1,200 per year.
How much energy will you need to buy when the sun's not out and your battery is low? They won't power you for 365 days a year.
I might be wildly out here, but maybe when you're 80 the panels will start paying for themselves? Is that worth it? How much value will they add to the home? Unless you're going to be using them for 20 years + I'd have to seriously wonder if it was worth all that outlay.
My mum inherited solar panels with her house and is on an old scheme that buys her excess leccy at some ridiculous price. She gleefully informs me that even after buying a tank of oil for the heating her total energy bills have worked out at about £6 per month, taking into account payments from the national grid and the government's £67 monthly help. Makes me cry.
Efficiency losses will only reduce the amount of time that the battery can supply the 7kw,, not prevent its ability to do so.
It’s nearly forty years since I completed my degree and in a more mechanical biased discipline, but this is fairly basic stuff. I’d have thought that as you are being paid to do research in this area, this would be bread and butter to you? Or is your are of research more on the chemistry side rather than the physics?
A little more info..
I have an electric car. An MG5 which is not a high end vehicle but it suits me. I already have a Podpoint charger fitted. The car can only accept AC at max 7kwh. The battery is a Purestorage II DC 5kwh. The inverter is a hybrid Solis mini 4G (700-3600W) and the panels are Jasolar JAM60S21 370W MBB
As regards payback time that will depend on what happens to electricity prices long term... obviously the more they rise the quicker payback is reached. But as I have no plans to sell and move on anything I spend on solar is just as much of an investment in the property as would be a new kitchen or a conservatory so payback isn't a major concern.
My current consumtion is approx 3600 kwh per year not including the car, which even though I have a Podpoint charger fitted I charge at Tesco at 25p/kwh simply bevause my current EDF tariff is 37.54p/kwh. I only do something like 2000 miles a year which uses probably 700 kwh, but I obviously want to take advantage of solar for the car. I understand it won't completely cover the charging of the car but it will contribute, especially if I can change to Octopus from EDF.
Hope above info helps
Rob
That's where the EV thing starts to get really interesting, genuine future/ green stuff...If, when, I can use abundant free solar to run the motor and perhaps partly the house as well...amortize the expenses over a sensible time frame and the tech/ battery/ gubbins isn't made in China. Just thinking aloud.
Made a more extensive comment in the other recent thread. Paid 8k for a bigger system (4.6kw/12 panels) and bigger battery (6.5kwh) just last September. I know for certain equipment prices have not risen 50 percent over that period despite what some will tell you.
Therefore it's primarily installers making an awful lot of hay while demand is high. Some might say good luck to them but it seems out of all proportion to me.
I'm not an electrical engineer / researcher.
All I was trying to explain in my original post was that in my opinion the OP won't get any useful EV charging experience with that system alone. i.e that he would always need some grid augmentation and more so in the future.
I think that you’re letting the 5kw storage battery confuse the issue. The OP can leave his car plugged in whenever he’s at home and charge his car at up to 4.5kw per hour. Once full, it can switch to the 5kw battery to power the house.
Depending on his mileage, he may never need to use power from the grid to charge his car (in the summer at least) or to run his house.
He doesn’t just need to use the 5kw battery to charge his car, it’s just additional storage capacity from his panels.
I believe that there are vehicles that can supply power to the house so the small storage battery may actually become redundant at done stage.
Let's assume the OP has a Tesla Model S. @ 3.7KW that will take 21 hours to fully charge, for 4.5KW lets say @ 18 hours. So, to charge his Tesla he needs his panel outputting its full 4.5KW for 18 hours. Unlikely i would suggest, hence he will need power from the grid to fully charge. If however he had a 22 KW panel he could charge his tesla in 5 hours, 50KW in 2hours and 150KW less than an hour. Much more useful and a much better charging experience. Now let's assume that he doesn't have room for a solar farm but does have room for a battery and that next gen LTO/NTO can can provide 50KW in an acceptable form factor. Now he has a much more useable charging experience.
I think you only see batteries as storage for panel output whereas i see them as storage and boost, charged by microgen and cheap off peak grid supply then used when needed for a cheaper more efficient charging experience.
I do not agree that vehicle to grid will make smart battery storage redundant.
I’m not sure why a question about solar panels and home battery has gone down a ‘useless for charging EVs’ rabbit hole?
The point is, and using the Tesla example, you could either charge it 100% from the grid, or you could use whatever energy the panels can generate to charge it, reducing demand on the grid. 7kW home charging will likely be the norm for a long time, 22kW and 50kW charge rates from a house battery is a long way off.
I don’t see the contention to be honest.
Quite a few EVs do Vehicle to Load nowadays, having a 50kWh+ battery sitting outside available to power something is useful. Vehicle to Grid will be more useful still, having X MWh available to support the grid at times of peak demand will definitely change the picture for the good.
Back to the panels/battery question, there’s no doubt that installers are pushing up prices along with the demand, can’t see that changing until either electricity prices drop or supply of the panels and associated tech frees up.
The OP has an MG5, presumably the 50kwhr model. But let’s say the 60kwhr to be on the safe side. Doing an average of 200 miles per week at 4m/kwhr, he’ll need 50kw from his panels or about 20 hours in total if his panels are producing 4kw output. Depending on many factors, his system may therefore be able to supply all of his motoring needs.
Granted larger, more advanced systems which are not currently available, wound probably make life easier, but what you are talking about is not available to my knowledge but if it is, it will undoubtedly be st a substantially higher cost than is viable. Maybe it will come but it’s still a long way off.
For what it’s worth, I can see storage batteries being useful longer term but not small ones when the car has a much larger battery which can be utilised.
Indeed. Regretting not keeping my mouth shut ;-)
As an aside, I was chatting with a neighbour last week. He has a 20 panel array and no battery or EV. His display on a cold mid winter day was showing that he was using 300w in the house and putting 4.5kw back to the grid.
It was crying out for a battery or better, an EV.
Might have already been said but if you're producing 4.5kw full chat why not just have the car connected and use the power straight from the array? It’ll mean youre only paying 3 kwh when youre charging your car. Sorry but still dont get the battery thing currently, especially winter months
OP - I say go for it! Cheaper than here in Portugal as your system includes batteries! Do consider how much sun you get in your area and the positioning and angle of the panels. You may need to adjust the suggestions. You can actually get figures from a website - PVGIS-5 estimates for solar power generation https://re.jrc.ec.europa.eu/pvg_tools/en/
usage guide here: https://joint-research-centre.ec.eur...arted-pvgis_en
Here is the output for Swansea
Last edited by MartynJC (UK); 27th January 2023 at 21:07.
“ Ford... you're turning into a penguin. Stop it.” HHGTTG
You can charge solely from the array at 4.5kw. There’s no need to use any from the grid. It will just take longer, that’s all.
Is that using the podpoint app though?
I had a 15 panel outfit and came to the same conclusion 3 years ago so bought an extra 4 panels and a Tesla Powerwall). I get free electricity (5 bed house) for 8 months of the year. Plus the remaining 4 months are funded by my FIT. The £60/month from HMG is just a bonus. Happy days.
Whoever does not know how to hit the nail on the head should be asked not to hit it at all.
Friedrich Nietzsche
Time to payback is one measure often quoted, and our projection on the back of an envelope has dropped from around 11 to around 7 years for obvious recent reasons.
However, much more relevant for those of us with enough sitting in ‘high’ interest accounts, even at todays slightly increased interest rates, is the annual return on investment. The panel skeptics never seem to think of this.
Switching some of my lump sum from an account (0.5% or so at the time) to panels (6.5% at the time) was a no-brainer, and the equation still works now although the numbers are temporarily different.
We have 2 EV’s, which for most of the time are sitting on the drive doing nothing so for us being able to use the car batteries as storage would be a game changer. We looked at getting solar panels last year but it only made sense if we also got a battery, but then paying another £6k or so for a relatively small battery when we already have 140kwh of batteries sitting on the driveway seemed like a waste. Hopefully vehicle to load will become a practical option in the next few years.
Sent from my iPhone using TZ-UK mobile app
You know those people that say ‘I passed my Maths O level back in the 80’s and I’ve never used half of it’? Well, if I’d known about energy costs, solar panels and EV’s I’d have stuck around and done the A level. Hell, maybe I should have done a PhD??!!
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