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Solar Panels UK - is it worth it?
- Thread starter jdwuk
- Start date
PITA
Model 3 Performance
Here's December 2020... when we had no Solar, no Ev, no Chargers, no Induction Cooking, No Heat Pump. The only thing we had was one single Powerwall.
Then in December 2021 we had installed the Solar Array, 2nd Powerwall, Ev Charger, Heat Pump & Induction Cooking.
Our consumption increased by 1,000 kWh
So we went from 27.8 kWh per day average... in December 2020
To 59 kWh per day average... in December 2021.
PITA
Model 3 Performance
I calculated that if we had 50 kWh battery storage, that would give us plenty of scope to store, use & charge the cars ... Winter, Summer & decent Blackout minimum levels.
PITA
Model 3 Performance
Oh... at the new OFGEM April 2023 price cap estimates...
... our 18,000 kWh would be about £ 14,700 per year... just for electricity (Inc Standing Charge).
So my ROI is going from Decades, to Years, to Months
... our 18,000 kWh would be about £ 14,700 per year... just for electricity (Inc Standing Charge).
So my ROI is going from Decades, to Years, to Months
PITA
Model 3 Performance
Also... at the new OFGEM April 2023 price cap estimates...
... our 18,000 kWh would be about £ 14,700 per year... just for electricity (Inc Standing Charge).
So my ROI is going from Decades, to Years, to Months... at this rate
Putin is smashing up my ROI figures like a champ
... our 18,000 kWh would be about £ 14,700 per year... just for electricity (Inc Standing Charge).
So my ROI is going from Decades, to Years, to Months... at this rate
Putin is smashing up my ROI figures like a champ
For sure, ballpark figures on back of fag packet as an illustration.... Many, many variables which would go to pages otherwise.
RedMod3
Member
Absolutely right and the same for me. Here was I doing my calculations thinking one PW would be sufficient, then I needed two for summer and three for winter and that is not really enough. Us Tesla drivers with 2, 3 or 4 PWs will not need to fear power cuts this winter as we really will be well prepared.Also... at the new OFGEM April 2023 price cap estimates...
... our 18,000 kWh would be about £ 14,700 per year... just for electricity (Inc Standing Charge).
So my ROI is going from Decades, to Years, to Months... at this rate
Putin is smashing up my ROI figures like a champ
From experience, I disagree slightly but that’s based on personal circumstance. With 2 Powerwalls, I have 27kWh storage. At this time of year the boiler is off and the immersion runs 4 times per day on schedules and tops up with surplus solar. On averageI have about 50% capacity left in the morning if we do nothing unusual. My power cut reserve is 30% so there is wriggle room for other use after dark.
There is no right or wrong in the discussion except that solar without battery is strawberries without cream
PITA
Model 3 Performance
RedMod3
Member
Absolutely,Solar with battery's and air conditioning... is strawberrys and ice cream... yum yum
Even with 5.1kW net generation, 30C+ heat has cut my peak generation today to only 4.0kW and our place is using 2,2kW as the heatpump is working hard to keep as cool. PWs only at 64%, so I may top them up tonight.
All three features are really needed in this weather.
PITA
Model 3 Performance
Ooft... latest OFGEM prediction is £5,000 by April 2023
Energy bills will pass a staggering £5,000 next year in the bleakest forecast yet for households struggling to make ends meet in the cost of living crisis.
Experts have predicted regulator Ofgem will be forced to increase the cap to £5,038 per year for the average household in the three months beginning next April.
The latest prediction is that the cost of gas will be capped at 18.02p per kilowatt hour and 70.34p per kWh of electricity.
The new prediction is based on today’s energy price on wholesale markets. The final price is calculated by tracking the wholesale price over several months.
www.independent.co.uk
Energy bills will pass a staggering £5,000 next year in the bleakest forecast yet for households struggling to make ends meet in the cost of living crisis.
Experts have predicted regulator Ofgem will be forced to increase the cap to £5,038 per year for the average household in the three months beginning next April.
The latest prediction is that the cost of gas will be capped at 18.02p per kilowatt hour and 70.34p per kWh of electricity.
The new prediction is based on today’s energy price on wholesale markets. The final price is calculated by tracking the wholesale price over several months.
UK energy bills could hit £5,000 in April, bleak new forecast says
Prediction comes as ministers are set to press energy companies for a solution
www.independent.co.uk
PITA
Model 3 Performance
So... at 70.34p ... my 18,000 kWh in the year would cost £ 12,661 (plus whatever the Standing Charge will be).
That's only £1,055 per month
... just for the electric.
That's only £1,055 per month
... just for the electric.The press are basically looking for the most outlandish predictions and printing them, because doom sells papers.
Auxilione were literally formed a month ago. They're based out of a house in Burnley. Any one of us could be 'Experts' according to the papers.. let's predict the price will be 10,000 by January..
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RedMod3
Member
Or could be much less with solar, battery and full electric heating and cooling. This is my bill for today for any doubters that all 3 needed for a comfortable life.So... at 70.34p ... my 18,000 kWh in the year would cost £ 12,661 (plus whatever the Standing Charge will be).
That's only £1,055 per month
PITA
Model 3 Performance
Busy, busy, busy...
At the new OFGEM price cap in January '23, at 21.8 kW it'll be costing me about £15 per hour
(£131,400 for the year at that rate)Good job it's only costing me £1.64 per hour until April 2023
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PITA
Model 3 Performance
Sure... our house was originally Single Phase (L1). With a Single Phase Consumer Unit.
When I had the Powerwalls, Gateway, 7kW Ev charger and Solar Array fitted, they were all fitted on this Single Phase (L1). Just like a normal house.
The backup side of the house is all on that Single Phase circuit. So we've never had any 'balancing' issues.
When I had 3 Phase fitted, we installed an outside 3 Phase smart meter (relocated into a bigger box) and outside 3 Phase distribution board.
So nothing changed on the Single Phase side.
Now from the 3 Phase Distribution board we installed a 22kW 3 Phase EV Charger. This is downstream by the Smart Meter and is not on the backup side.
This 22kW charger has the primary Phase being L2. So if a 7kW car started charging on the 3 Phase unit... it would only use the Single Phase line L2, leaving L1 to power the house.
We're going to have a big kitchen extension... and will tap into the 3 Phase distribution board for high energy appliances (not on backup side)... but then for other critical kitchen appliances we'll use the backup Single Phase Consumer Unit.
All the Air Conditioning heat pump is on the backup Single Phase side.
Our 3 Phase cabling upgrade & Smart Meter cost us nothing. The DNO (Western Power) upgraded us for free (but estimated the work to be at least £7500). We were a 'pathfinder' experiment which I talked my way into
The 3 Phase Distribution Board install was done at the same time the 22kW Ev Charger was fitted with about 30 metres of 3 Phase cabling. That cost me £2,500
So I'm 2 months in (or so) and thought it worth writing up my experience for people. Its been quite a trip with many on here helping massively along the way.
TL/DR:
We got panels, 19 of them.
Install was more involved than expected, but OK
Fully solar powered in June & July, saving about £180/month so far in the summer
So.energy - reasonably happy with.
Pure drive 10kw battery - probably wouldn't recommend but working fine
Full story
The Plan
Reminder of the plan since around March time. We happened to be talking to so.energy about panels and batteries when the Ukraine thing kicked off and the price of power started going mad(er), realising this likely would lead to additional supply demand on solar we fairly rapidly firmed up a commitment to using them and got on with some simulating. We already had full electric in the house - Heatpump for water and heating, M3, induction cooking and so on, so were using a lot of power, although roughly equivalent to the value of gas we were using pre-conversion.
On the advice of @PITA (I think) I investigated populating our split roof with some panels facing the NE, in addition to what installers would usually recommend on the SW roof. Frustratingly the NE roof is overall a better shape for panels, but that's life. We eventually settled on 8x375w panels on the NE, 14x375w on the SW and a 10kw Puredrive battery. They initially quoted for an 8kw Solus inverter, and that is what is currently installed.
So.energy were ...decent... through out. They always got back to questions, and answered some pretty techie stuff well. Only downside was that replies to emails generally took ~5 working days. But they were answered and always within that time, and always well, so I was actually reasonably happy. I stuck with them, as I said due to having a place in the queue booked, all the equipment looked decent although not cutting edge and a key thing for me - its a big company with interests beyond solar. So everything comes backed with a 10 year guarantee and there is a reasonable chance they will be around that long.
Total price was £12400, with payback at today's prices in 5.5 years. I'm hearing horrible rumours of 75p/unit in the future, which would make this pay off in 2.5 years, hopefully it doesn't come to that however!
The install
Install days approaches and a scaffolder turns up to measure. His plans call for blocking a neighbours drive for a week. I tell him that's not going to fly, so he does a re-design. He also inserts a bunch of 'safety measures' which I say sound like I good idea, and he takes that as authorisation to spend more than planned. Not sure why so.energy let him off with that, but it wasn't reflected in my price so *shrug*.
About this time I start getting calls from a lead at so.energy. Apparently my SW facing array should have Tigo optimisers as 4 of the panels are at slight different angles (possibly 15 degrees of a difference) and they wanted to install them on all the panels, but can't even get 4 to put on the ones with the variation. He insists that the inverter just won't start up at all with 4 panels on a different plane. I (still) think that's BS - they might limit the total output to the lowest common denominator, but with no shading and not that much variation I am unconvinced it would have ben worse than adding that extra kw of installed panel. 2 of the panels I wasn't that bothered about (they had been moved from the NE side to aid the aesthetics on the less productive side), but I really would have liked the other 2. Still no go - option of wait for the Tigos to be back in stock (August sometime), with the scaffolding up, or drop those 4 panels. I used these conversations to persuade them that with a split array I really didn't need the 8kw inverter as we would be maxing out in a practical sense at ~4.6kw. Given we should be aiming to clip a little, 8KW is massively oversized and the more senior designer agreed. We settled on a 5kw as it was the smallest their software would allow given the size of the array, even tho they were facing different directions.
All agreed, deliveries start turning up. But 22 panels and an 8kw inverter and the battery all arrive. This is going to be interesting.
After many discussions we agree that actually we can squeeze 11 panels into the space that they had planned 10, stick with the 8 on the NE, and they will ship a 5kw to me ASAP and do a swap. This ends up with 8x375 = 3kw installed NE array, and a 4.125kw SW facing array for a total install of 7.125kw installed panels.
The guys doing the install were great, but it was good I was very familiar with the house and there to solve problems. As we wanted all the cabling etc routed internally it was pretty much up to me to spec exactly where to route things. At one point I had to get under the house and rescue one of the guys as he got lost, and had planned to leave ~100m of armoured cable winding all over the place for the battery. I sorted that out and cut it down to the 7m it needed to be. Well worth taking a day off if you want to be particular about the install I would say!
Anyway, all in and installed in 2 days, stressful but largely happy result all around.
Performance
Since installation we have generated (and used almost all of) 1077kwh, saving around £300. Until last week we hadn't used any grid power at all, other than a couple of errors I made and charging the car. With a couple of duller days this week I have converted over to charging the battery at night on our E7 rate rather than running it down over night, trying to get a feel for what level it has to be at to make it through the day and evening on sunlight.
The split array is working pretty well, a typical bright day looks like this for the 2 arrays:
That NE array (in grey) really supporting and getting that early boost in the morning. On a cloudy day the 2 curves almost match, and thats where just the sheer number of panels helps.
I have started using solcast.com.au to predict the energy which is working well (which is where the data for the above pic comes from). However doing that has highlighted that the 8kw inverter is really hamstringing us on dull days. On a good day, the forecast will be within ~5% of what we get, but consistently if the forecast is 10kwh or lower, our actual production drops off a cliff. The 15th of this month was predicted to be ~8.6kwh, but we only produced 3, 16th predicted to be 10 and we got 6.3. Today (17th), 23.7 predicted, 22 delivered. It could just be a forecasting error, but there is enough other data to support that there is a problem at the bottom of the scale. This is because we are operating in the cliff part of the inverter efficiency curve in low output - 800w is 10% of the rated power, and destinctly in to sub 90% efficiencies. At 500w we could be down to ~60% (can't find the specific curve for our inverter, so guessing a bit). Swap to the smaller inverter is booked so hopefully these numbers will improve.
Battery
Now for the weird bit. The battery. These look pretty funky looking at the datasheet and pictures:
Reviews on line are largely positive (except one youtuber who I decided was just a dick and insisted on sending it back because the installer hadn't put any warning stickers on it. Hopefully no one here) so I went for it. A generous interpretation of the data sheet gives you a 5kw discharge rate and either an unspecified or 3.7kw charge rate if you do the sums. Both are unfortunately wrong. To be clear, the max discharge is 3kw (which is actually reasonable enough to do the job) but the max charge rate is only 1.8kw. Which is pretty meh. It also only discharges day to day to between 10 and 15%, after which it starts cycling between that and 20% if you are out of juice. This just means that you start paying extra for your power as you have to pay a conversion fee each time you put power in or out of the battery. The charge rate also limits you somewhat. Assuming the last kw is reserved, [email protected] needs 5 hours to charge, not the 4 octopus would generally give you.
The UI is also, rubbish. There is a nice app from Pure Drive that lets you monitor stuff:
but you can't change anything there. Setting charge times or levels all comes through the HTTP interface for the battery its self. Quite a nice front end:
but setting anything is deep in a horrible menu system. 20 clicks (I just counted) through stuff like this:
The battery charge schedule is just off the bottom of that screen - I have to scroll past the option to enable 3 phase every time I want to change the charge level. Or stop that bouncing by putting a fake charge level to 15% until the cheap times at midnight. And again when I have to remember to turn that off before the next day (no one time option in the UI).
I love having access to all this, but day to day its a complete pain and TBH one day I'm going to break something either by fiddling, or by mis clicking on the phone.
What it does expose however is that this the puredrive battery may be a pretty neat battery, but the overall package is actually co-ordinated by a Victron Energy MultiPlus-II. I've not delved in too far yet, but there is a pretty large online community setup to support these. They mostly run boat battery systems, but they are also used for hospital backup power and so on. So pretty good stuff, but I still need a way around using the HTML interface.
Finally, it does do anti-islanding, but only for 1 down stream circuit, not the house. I'm still debating if I should attempt to use this and move the servers, lights and kitchen sockets onto it. It would be quite a pain as we already have 3 CUs now - a 4th is going to be really tight!
Definitely slightly grumpy about the battery, but it is working and I do plan to have an entertaining discussion with them at some point soon about the charge, discharge rates and a UI for controlling overnight charging and applicability of consumer protection laws around clarity of advertising.
Future plans:
TL/DR:
We got panels, 19 of them.
Install was more involved than expected, but OK
Fully solar powered in June & July, saving about £180/month so far in the summer
So.energy - reasonably happy with.
Pure drive 10kw battery - probably wouldn't recommend but working fine
Full story
The Plan
Reminder of the plan since around March time. We happened to be talking to so.energy about panels and batteries when the Ukraine thing kicked off and the price of power started going mad(er), realising this likely would lead to additional supply demand on solar we fairly rapidly firmed up a commitment to using them and got on with some simulating. We already had full electric in the house - Heatpump for water and heating, M3, induction cooking and so on, so were using a lot of power, although roughly equivalent to the value of gas we were using pre-conversion.
On the advice of @PITA (I think) I investigated populating our split roof with some panels facing the NE, in addition to what installers would usually recommend on the SW roof. Frustratingly the NE roof is overall a better shape for panels, but that's life. We eventually settled on 8x375w panels on the NE, 14x375w on the SW and a 10kw Puredrive battery. They initially quoted for an 8kw Solus inverter, and that is what is currently installed.
So.energy were ...decent... through out. They always got back to questions, and answered some pretty techie stuff well. Only downside was that replies to emails generally took ~5 working days. But they were answered and always within that time, and always well, so I was actually reasonably happy. I stuck with them, as I said due to having a place in the queue booked, all the equipment looked decent although not cutting edge and a key thing for me - its a big company with interests beyond solar. So everything comes backed with a 10 year guarantee and there is a reasonable chance they will be around that long.
Total price was £12400, with payback at today's prices in 5.5 years. I'm hearing horrible rumours of 75p/unit in the future, which would make this pay off in 2.5 years, hopefully it doesn't come to that however!
The install
Install days approaches and a scaffolder turns up to measure. His plans call for blocking a neighbours drive for a week. I tell him that's not going to fly, so he does a re-design. He also inserts a bunch of 'safety measures' which I say sound like I good idea, and he takes that as authorisation to spend more than planned. Not sure why so.energy let him off with that, but it wasn't reflected in my price so *shrug*.
About this time I start getting calls from a lead at so.energy. Apparently my SW facing array should have Tigo optimisers as 4 of the panels are at slight different angles (possibly 15 degrees of a difference) and they wanted to install them on all the panels, but can't even get 4 to put on the ones with the variation. He insists that the inverter just won't start up at all with 4 panels on a different plane. I (still) think that's BS - they might limit the total output to the lowest common denominator, but with no shading and not that much variation I am unconvinced it would have ben worse than adding that extra kw of installed panel. 2 of the panels I wasn't that bothered about (they had been moved from the NE side to aid the aesthetics on the less productive side), but I really would have liked the other 2. Still no go - option of wait for the Tigos to be back in stock (August sometime), with the scaffolding up, or drop those 4 panels. I used these conversations to persuade them that with a split array I really didn't need the 8kw inverter as we would be maxing out in a practical sense at ~4.6kw. Given we should be aiming to clip a little, 8KW is massively oversized and the more senior designer agreed. We settled on a 5kw as it was the smallest their software would allow given the size of the array, even tho they were facing different directions.
All agreed, deliveries start turning up. But 22 panels and an 8kw inverter and the battery all arrive. This is going to be interesting.
After many discussions we agree that actually we can squeeze 11 panels into the space that they had planned 10, stick with the 8 on the NE, and they will ship a 5kw to me ASAP and do a swap. This ends up with 8x375 = 3kw installed NE array, and a 4.125kw SW facing array for a total install of 7.125kw installed panels.
The guys doing the install were great, but it was good I was very familiar with the house and there to solve problems. As we wanted all the cabling etc routed internally it was pretty much up to me to spec exactly where to route things. At one point I had to get under the house and rescue one of the guys as he got lost, and had planned to leave ~100m of armoured cable winding all over the place for the battery. I sorted that out and cut it down to the 7m it needed to be. Well worth taking a day off if you want to be particular about the install I would say!
Anyway, all in and installed in 2 days, stressful but largely happy result all around.
Performance
Since installation we have generated (and used almost all of) 1077kwh, saving around £300. Until last week we hadn't used any grid power at all, other than a couple of errors I made and charging the car. With a couple of duller days this week I have converted over to charging the battery at night on our E7 rate rather than running it down over night, trying to get a feel for what level it has to be at to make it through the day and evening on sunlight.
The split array is working pretty well, a typical bright day looks like this for the 2 arrays:
That NE array (in grey) really supporting and getting that early boost in the morning. On a cloudy day the 2 curves almost match, and thats where just the sheer number of panels helps.
I have started using solcast.com.au to predict the energy which is working well (which is where the data for the above pic comes from). However doing that has highlighted that the 8kw inverter is really hamstringing us on dull days. On a good day, the forecast will be within ~5% of what we get, but consistently if the forecast is 10kwh or lower, our actual production drops off a cliff. The 15th of this month was predicted to be ~8.6kwh, but we only produced 3, 16th predicted to be 10 and we got 6.3. Today (17th), 23.7 predicted, 22 delivered. It could just be a forecasting error, but there is enough other data to support that there is a problem at the bottom of the scale. This is because we are operating in the cliff part of the inverter efficiency curve in low output - 800w is 10% of the rated power, and destinctly in to sub 90% efficiencies. At 500w we could be down to ~60% (can't find the specific curve for our inverter, so guessing a bit). Swap to the smaller inverter is booked so hopefully these numbers will improve.
Battery
Now for the weird bit. The battery. These look pretty funky looking at the datasheet and pictures:
Reviews on line are largely positive (except one youtuber who I decided was just a dick and insisted on sending it back because the installer hadn't put any warning stickers on it. Hopefully no one here) so I went for it. A generous interpretation of the data sheet gives you a 5kw discharge rate and either an unspecified or 3.7kw charge rate if you do the sums. Both are unfortunately wrong. To be clear, the max discharge is 3kw (which is actually reasonable enough to do the job) but the max charge rate is only 1.8kw. Which is pretty meh. It also only discharges day to day to between 10 and 15%, after which it starts cycling between that and 20% if you are out of juice. This just means that you start paying extra for your power as you have to pay a conversion fee each time you put power in or out of the battery. The charge rate also limits you somewhat. Assuming the last kw is reserved, [email protected] needs 5 hours to charge, not the 4 octopus would generally give you.
The UI is also, rubbish. There is a nice app from Pure Drive that lets you monitor stuff:
but you can't change anything there. Setting charge times or levels all comes through the HTTP interface for the battery its self. Quite a nice front end:
but setting anything is deep in a horrible menu system. 20 clicks (I just counted) through stuff like this:
The battery charge schedule is just off the bottom of that screen - I have to scroll past the option to enable 3 phase every time I want to change the charge level. Or stop that bouncing by putting a fake charge level to 15% until the cheap times at midnight. And again when I have to remember to turn that off before the next day (no one time option in the UI).
I love having access to all this, but day to day its a complete pain and TBH one day I'm going to break something either by fiddling, or by mis clicking on the phone.
What it does expose however is that this the puredrive battery may be a pretty neat battery, but the overall package is actually co-ordinated by a Victron Energy MultiPlus-II. I've not delved in too far yet, but there is a pretty large online community setup to support these. They mostly run boat battery systems, but they are also used for hospital backup power and so on. So pretty good stuff, but I still need a way around using the HTML interface.
Finally, it does do anti-islanding, but only for 1 down stream circuit, not the house. I'm still debating if I should attempt to use this and move the servers, lights and kitchen sockets onto it. It would be quite a pain as we already have 3 CUs now - a 4th is going to be really tight!
Definitely slightly grumpy about the battery, but it is working and I do plan to have an entertaining discussion with them at some point soon about the charge, discharge rates and a UI for controlling overnight charging and applicability of consumer protection laws around clarity of advertising.
Future plans:
- More automation of everything. I'm running fully manual just now to get a feel for the decision tree needed to minimise our grid intake. Plan however is to move my forecasting from excel into some python which will then configure the battery over night charge appropriately, set the heatpump to absorb any extra power and email me telling me to plug in the car (or not).
- I also have the Andersen A2 charger set up so it should be able to absorb extra power, but the CT clamp its using is reading inaccurately, and when it tries to grab power the house battery starts discharging into the car which I don't want (again, that round trip)
- There is 1 panel that could do with a Tigo optimiser (it gets shaded by a dormer later in the day), for £30 I'm willing to give it a shot and seeing if it helps)
- I need to get an eddie to divert excess power through the day into the HW, rather than triggering a heat cycle on the HP. Although this works, there are often a few 100w's being exported through the middle of the day as we exceed that 1.8kw absorption and capturing them to put into the water, even in an inefficient immersion way would be better
