That’s serious money for the PW. Presume +VAT. My first one was about £7500 in 2018 and the second was under £7000 in 2019. That said my meter is the other side of the garage wall from my PW’s and the consumer unit sits above the PW’s, so cabling was minimal.
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Thinking about solar cells and powerwall.
- Thread starter sliyk
- Start date
Glan gluaisne
Active Member
I've been pricing up options other than the Tesla PW for a while now. Longest cycle life option is almost certainly the Pylontech LFP packs. Their 10.65 kWh pack costs about £3,700 inc VAT, and coupled with a Sofar ME3000 inverter/charger at about £670 inc VAT is probably close to being one of the cheapest systems around. At a guess, the LFP cells in the Pylontech packs may have a cycle life of maybe three or four times that of NCA cells. I have a set of 11 year old LFP cells that are still pretty much as good as they were when new, their main disadvantage is that they are bigger and heavier for any given capacity than other cell chemistries, but that's rarely an issue for home storage. Home storage does need a high cycle life, though, as unlike a car, home battery packs really get hammered on the number of charge/discharge cycles, at least 365 a year, maybe more.
MrBadger
Badger out
£6k for 4kWp solar seems steep to me. Thats not far off what I was quoted for over 6 years ago and prices have dropped considerably. I paid a bit more than that (including the VAT), but my system runs optimisers, had high end panels for aesthetic reasons and a hot water diverter. And no installation grant in those prices.
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I have contacted about 4 or 5 installers off the tesla official installer list from their website.
I am in the process of getting them here for surveys etc. Will then lay out the total prices for comparison and your opinions here too.
ACarneiro
Active Member
I paid around £10k for 9.76kWp including inverter and optimisers. This is with high efficiency bifacial panels.
And to me. My E.On pricing is £9k inc. VAT all-in for 4kW solar and the 8.2kW GivEnergy battery system. £250/m on 0% finance.
I changed from Agile to the Tesla Energy Plan in October. I still compare it with Agile which is about 20% more expensive.I find that Tesla are charging the PW at similar times to those I was using under Agile.Although I no longer have the Agile Pay you days, the 8p always with no standing charge really works. Its also great to charge my 2 EVs when they need charging and not having to wait for Off Peaks.
Glan gluaisne
Active Member
In the medium to long term (say, 5 to 20 years) I believe there won't be any of these cheap deals around any longer. The reason they exist is because there are large profits to be made from arbitrage, buying electricity during the very low wholesale price periods, storing it, and then selling it back to the grid during the very high wholesale price periods. That works now, because there is a massive peak to tough variation within most 24 hour periods, sometimes from a negative price to over 30p/kWh.
There's a scramble to offer services to balance the grid at the moment, but once that market is satisfied, the normal laws of supply, demand and pricing will ensure that the wholesale price becomes closer to the mean, without the large variance seen at the moment. This large variance isn't just demand driven, much of it has arisen from the rapid growth in renewable generation, primarily wind. As soon as most of the big wind farms have battery packs (it's happening now) then they will be able to better regulate output in response to demand, and doing that means they get a steadier price for the electricity they export to the grid.
I strongly suspect that smart metering, variable domestic tariffs, etc will all cease to exist before too long, and we'll revert to fixed tariffs, perhaps with no cheap rates at all, simply because it costs less and is simpler to administer fixed tariffs. These future fixed tariffs may well be cheaper than the fixed tariffs available today, but more expensive than the cheap rate tariffs. I doubt they will be as cheap as the Tesla 8p/kWh rate, that is possible because of arbitrage profits, and they will virtually disappear at some future date.
If I were trying to work out the return on investment from battery storage, I would very definitely not use the cheapest deals around at the moment, because I very much doubt they will be around in ten years time.
There's a scramble to offer services to balance the grid at the moment, but once that market is satisfied, the normal laws of supply, demand and pricing will ensure that the wholesale price becomes closer to the mean, without the large variance seen at the moment. This large variance isn't just demand driven, much of it has arisen from the rapid growth in renewable generation, primarily wind. As soon as most of the big wind farms have battery packs (it's happening now) then they will be able to better regulate output in response to demand, and doing that means they get a steadier price for the electricity they export to the grid.
I strongly suspect that smart metering, variable domestic tariffs, etc will all cease to exist before too long, and we'll revert to fixed tariffs, perhaps with no cheap rates at all, simply because it costs less and is simpler to administer fixed tariffs. These future fixed tariffs may well be cheaper than the fixed tariffs available today, but more expensive than the cheap rate tariffs. I doubt they will be as cheap as the Tesla 8p/kWh rate, that is possible because of arbitrage profits, and they will virtually disappear at some future date.
If I were trying to work out the return on investment from battery storage, I would very definitely not use the cheapest deals around at the moment, because I very much doubt they will be around in ten years time.
MrBadger
Badger out
I used an installer based around Reading. I don't know how far they will travel but DM me if you want more info. Last I spoke with them they were not yet doing batteries, but things may have changed since then - just over a year ago. They were really good so happy to recommend but unfortunately unable to help me out on this occasion.
Thanks. I have contacted almost all the local powerwall supplier listed on the tesla powerwall website. Maybe cause they are listed there so they are expensive?
I also contacted joju solar who supplied the chap who had the YouTube channel fully charged. They charge 9880 Inc vat for just the powerwall!
ACarneiro
Active Member
I thought I would share my thoughts after recently going through this exercise.
I had a number of quotes recently one from Joju Solar and one from Tehys Energy in Reading. I think I was there most demanding customer with the amount of questions and variants I went through.
Effectively a Powerwall is about £10K installed with the backup gateway. I am on 3-phase so my costs will be slightly higher than most.
Couple that with an 8kWp 20 panel solar array and that rises to £18K. That includes £1K of scaffolding over a rear extension and glass conservatory too.
The 20 panels are high output, and connected to a 3-phase solar edge inverter too.
You also have to realise that there is no more 5% VAT rate anymore unless you hit certain criteria. So at least you need to take the older prices and add on an extra 15%. That is currently affecting the take up of solar and batteries.
I chose the Powerwall over the other batteries due to the unlimited cycle times, the peak and continual load and the fact that Tesla claim they will either offer subsidised repairs or a trade in value against replacement if the pack fails out of warranty. The last thing I wanted was to have a set of very large faulty batteries sat in the garage which I could not dispose off.
Appreciate everyone will have different reasons for their choices.
The export payments are not worth a hoot. payback for me is around £60 per year. Overall can it pay? well yes, its hard to predict the future though, it depends on usage etc. I have come up with my own model, it is conservative compared the the standard MCS calculations provided by the installers. I am not really looking for a payback but had to sell it to the missus under the "Spend to save" budget.
Below are my forecasts on annual energy usage of 9,681kWh. I have made the assumption that in 5 years the Octopus go tariff may no longer exist and will therefore follow the cost of a standard tariff. Costs include maintenance, the second chart shows the break even costs with a battery trade in too. As noted in a previous post the hardest thing to forecast is the tariff changes, you really only make a big saving whilst there is cheaper hours to charge your battery/car. Failing that you move to the Tesla Energy tariff, where effectively Tesla manage and cycle your battery umpteen times a week/day, effectively reducing the life of it, without extending the warranty to compensate.
Not to say the figures are correct, but worth sharing the result from my own model. So that gives me a payback of 16 years against Octopus Go and 19 years if I add a replacement battery. Am hoping that those figures turn out to be too conservative, but if the tariffs change considerably then it is anyones guess. Touch wood we will recoup the costs. If not at least I will have the satisfaction of heating and lighting during a power outage. If you are looking for a ROI then look at investments or your pension, if you are looking to be self sufficient or reduce your CO2 then look at solar, it all depends on what your drivers are.
I had a number of quotes recently one from Joju Solar and one from Tehys Energy in Reading. I think I was there most demanding customer with the amount of questions and variants I went through.
Effectively a Powerwall is about £10K installed with the backup gateway. I am on 3-phase so my costs will be slightly higher than most.
Couple that with an 8kWp 20 panel solar array and that rises to £18K. That includes £1K of scaffolding over a rear extension and glass conservatory too.
The 20 panels are high output, and connected to a 3-phase solar edge inverter too.
You also have to realise that there is no more 5% VAT rate anymore unless you hit certain criteria. So at least you need to take the older prices and add on an extra 15%. That is currently affecting the take up of solar and batteries.
I chose the Powerwall over the other batteries due to the unlimited cycle times, the peak and continual load and the fact that Tesla claim they will either offer subsidised repairs or a trade in value against replacement if the pack fails out of warranty. The last thing I wanted was to have a set of very large faulty batteries sat in the garage which I could not dispose off.
Appreciate everyone will have different reasons for their choices.
The export payments are not worth a hoot. payback for me is around £60 per year. Overall can it pay? well yes, its hard to predict the future though, it depends on usage etc. I have come up with my own model, it is conservative compared the the standard MCS calculations provided by the installers. I am not really looking for a payback but had to sell it to the missus under the "Spend to save" budget.
Below are my forecasts on annual energy usage of 9,681kWh. I have made the assumption that in 5 years the Octopus go tariff may no longer exist and will therefore follow the cost of a standard tariff. Costs include maintenance, the second chart shows the break even costs with a battery trade in too. As noted in a previous post the hardest thing to forecast is the tariff changes, you really only make a big saving whilst there is cheaper hours to charge your battery/car. Failing that you move to the Tesla Energy tariff, where effectively Tesla manage and cycle your battery umpteen times a week/day, effectively reducing the life of it, without extending the warranty to compensate.
Not to say the figures are correct, but worth sharing the result from my own model. So that gives me a payback of 16 years against Octopus Go and 19 years if I add a replacement battery. Am hoping that those figures turn out to be too conservative, but if the tariffs change considerably then it is anyones guess. Touch wood we will recoup the costs. If not at least I will have the satisfaction of heating and lighting during a power outage. If you are looking for a ROI then look at investments or your pension, if you are looking to be self sufficient or reduce your CO2 then look at solar, it all depends on what your drivers are.
Glan gluaisne
Active Member
This is how I've been working out the return on a battery investment:
Our annual electricity cost is ~£617. Out of that, ~£55 is the standing charge, so the actual energy cost is ~£562
Breaking that down by time of day, we use about 56% of our electricity between 00:00 and 07:00, so ~£315 per year cannot be provided by our solar system, and the balance of of around £247 per year already includes day time use offset by solar generation.
Our solar system generates ~5,900 kWh per year, of which we self-consume about a third, so we have around 4,000 kWh of surplus generation available. However, about 85% of that surplus cannot be effectively stored in a battery system that doesn't have some sort of grid export capability, as our electricity usage during the summer months is very low, so the demand just isn't there to be able to make use of it. That leaves us with about 600 kWh of solar generation per year that we could usefully store in a battery system, for use later the same day. The value of that electricity, assuming it replaced peak rate electricity (currently we're paying 13.82p/kWh peak, 9p/kWh off-peak) would be be about £83 per year.
During the 5 months or so when solar generation is, to all intents and purposes, zero, or at least when there will never be any excess to store over normal consumption, we could offset all our daytime electricity use to the cheap rate, if we had a battery system with a usable storage capacity of around 10 kWh. Our mean daily peak rate electricity usage during the winter months is about 8.5 kWh, so for around 5 months of the year we could save the difference between the peak rate and off-peak rate for this usage. That comes to an annual saving of about £62 from time-shifting peak to off-peak using a battery system.
Adding up the savings, just for a battery system (as we've had the 25 panel PV system in our roof for several years now, and it's already paid for itself) we get a reduction in our electricity bill from having battery storage of about £145 per year. Our electricity bill would reduce from about £617 per year to about £472 per year.
The cheapest DIY install (by a competent person) battery system I can find, is 10.625 kWh Pylontech battery plus a Sofar ME3000 inverter charger. Including the odds and ends needed for the install as well as the equipment prices (things like DC isolation and over-current protection, AC isolation and over-current/earth leakage protection, cabling, junction boxes, glands etc) the price comes to about £4,500 inc VAT.
Assuming nothing ever failed with the battery system, then the payback period would be around 31 years. In reality, there is no way that any battery system is going to last that long, 15 years is probably the absolute maximum and more realistically the chances are that the capacity of the battery will have dropped by around 10 years to make the return reduce significantly.
The above is based on actual energy measurements we have for the major energy consuming items in the house, logged every 6 minutes over the past 4 years, so I know exactly when we use energy, and what's using it. The 25 panel PV system went live in March 2014, so I have over 6 years of data from that as to how much it really generates, and when. The "when" is critical. In summer we can easily generate 30 kWh per day more than we use, sometimes more. Even with a battery system we could never make use of that, as there is no point in having a battery system with a capacity that's much greater than the house winter peak time demand requirement.
Our annual electricity cost is ~£617. Out of that, ~£55 is the standing charge, so the actual energy cost is ~£562
Breaking that down by time of day, we use about 56% of our electricity between 00:00 and 07:00, so ~£315 per year cannot be provided by our solar system, and the balance of of around £247 per year already includes day time use offset by solar generation.
Our solar system generates ~5,900 kWh per year, of which we self-consume about a third, so we have around 4,000 kWh of surplus generation available. However, about 85% of that surplus cannot be effectively stored in a battery system that doesn't have some sort of grid export capability, as our electricity usage during the summer months is very low, so the demand just isn't there to be able to make use of it. That leaves us with about 600 kWh of solar generation per year that we could usefully store in a battery system, for use later the same day. The value of that electricity, assuming it replaced peak rate electricity (currently we're paying 13.82p/kWh peak, 9p/kWh off-peak) would be be about £83 per year.
During the 5 months or so when solar generation is, to all intents and purposes, zero, or at least when there will never be any excess to store over normal consumption, we could offset all our daytime electricity use to the cheap rate, if we had a battery system with a usable storage capacity of around 10 kWh. Our mean daily peak rate electricity usage during the winter months is about 8.5 kWh, so for around 5 months of the year we could save the difference between the peak rate and off-peak rate for this usage. That comes to an annual saving of about £62 from time-shifting peak to off-peak using a battery system.
Adding up the savings, just for a battery system (as we've had the 25 panel PV system in our roof for several years now, and it's already paid for itself) we get a reduction in our electricity bill from having battery storage of about £145 per year. Our electricity bill would reduce from about £617 per year to about £472 per year.
The cheapest DIY install (by a competent person) battery system I can find, is 10.625 kWh Pylontech battery plus a Sofar ME3000 inverter charger. Including the odds and ends needed for the install as well as the equipment prices (things like DC isolation and over-current protection, AC isolation and over-current/earth leakage protection, cabling, junction boxes, glands etc) the price comes to about £4,500 inc VAT.
Assuming nothing ever failed with the battery system, then the payback period would be around 31 years. In reality, there is no way that any battery system is going to last that long, 15 years is probably the absolute maximum and more realistically the chances are that the capacity of the battery will have dropped by around 10 years to make the return reduce significantly.
The above is based on actual energy measurements we have for the major energy consuming items in the house, logged every 6 minutes over the past 4 years, so I know exactly when we use energy, and what's using it. The 25 panel PV system went live in March 2014, so I have over 6 years of data from that as to how much it really generates, and when. The "when" is critical. In summer we can easily generate 30 kWh per day more than we use, sometimes more. Even with a battery system we could never make use of that, as there is no point in having a battery system with a capacity that's much greater than the house winter peak time demand requirement.
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MrBadger
Badger out
When calculating potential savings, it is important to take into account the expected lifespan of the cells. This is normally specified (if you go looking for it) in number of cycles. Whist there is not a cliff edge degradation at this cycle count, there will be a taper down over the life of the cells to a lower usable capacity, often hinted at in most warranties.
A simplistic approach to estimate the usable useful energy storage lifespan of a storage device would be to take the usable net storage capacity and the full cycle count to give a total lifespan energy storage potential. Subtract average round trip losses. Then use this energy storage potential and average electricity unit saving to calculate potential energy savings over the usable lifespan for the battery.
I won't put figures into this as different batteries have different usable net storage capacity and cycle counts and everyone will have different potential savings.
I did however some calculations for our battery setup. Rough figures below
4500 cycles, usable net storage 5.76kWh, 90% efficiency, average energy saving 9p/kWh (assumes no solar for simple calculation).
25920kWh lifetime energy, 23328kWh after losses
Potential energy saving (at 9p/kWh) £2100
Cost of 3 battery modules + mounts approx £2100. Expandable up to 8 modules. Excludes inverter and installation costs. Total hardware cost of system £3k.
A simplistic approach to estimate the usable useful energy storage lifespan of a storage device would be to take the usable net storage capacity and the full cycle count to give a total lifespan energy storage potential. Subtract average round trip losses. Then use this energy storage potential and average electricity unit saving to calculate potential energy savings over the usable lifespan for the battery.
I won't put figures into this as different batteries have different usable net storage capacity and cycle counts and everyone will have different potential savings.
I did however some calculations for our battery setup. Rough figures below
4500 cycles, usable net storage 5.76kWh, 90% efficiency, average energy saving 9p/kWh (assumes no solar for simple calculation).
25920kWh lifetime energy, 23328kWh after losses
Potential energy saving (at 9p/kWh) £2100
Cost of 3 battery modules + mounts approx £2100. Expandable up to 8 modules. Excludes inverter and installation costs. Total hardware cost of system £3k.
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Glan gluaisne
Active Member
Also worth noting that for a lot of the year the battery capacity won't come close to being fully utilised each day, so that needs to be factored in to both the cost saving and the cell life. It adversely impacts the return on investment (effectively being under-utilisation) but benefits the cell life significantly (cell cycle life is VERY heavily dependent of depth of charge/discharge per cycle).
Got some interesting reading for you guys. One of the quotes have come through. I have attached three pdf files with this post. They're quoting for two different type of sunpower panels. Would be interesting to see the expert's opinions here about pricing and which one I should go for. The 3d diagram is also a nice look, will still need to visit to give a final figure.
curmudgeon
Member
We're also looking at solar/battery options for our passive house design.
For those of us who are at home during the day, diverting excess solar to cars or hot water looks far more sensible and cheaper option than powerwall. Anyone doing this with 3-phase solar and ZAPPI/EDDI products?
What about micro-inverters?
For those of us who are at home during the day, diverting excess solar to cars or hot water looks far more sensible and cheaper option than powerwall. Anyone doing this with 3-phase solar and ZAPPI/EDDI products?
What about micro-inverters?
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