Lessons you've learned from your PV setup!!!
Discussion
Hi All,
For some reason i use an outrageous amount of electricity at home (about 1000 kw/month with no electric cars atm... so that will increase when i get another electric car at some time in the future)
anyway, i have decided to get a PV array and battery storage to assist in operating with greater efficiency.
The spec is somewhat limited by western power limiting our feedback to around 5kw as we only have single phase and no practical opportunity to upgrade (the pole at the end of the drive is only single phase - i'm scared to even ask about the upgrade cost.....)
i'm still at an extremely early stage so the proposed spec is still fluid, but it's looking like C. 15kw pv and about 10 KWh battery
Anyway.....
for those who are more knowledgeable than me, what lessons have you learned from your own PV/battery setup that you would like to pass on.
are there any traps i need to be aware of, hints and tips etc.
i intend to change my electricity tariff so i can charge the batteries in the dead of night if necessary at a cheaper rate if there is no sun the day before.
would it be sensible to put a small wind turbine up as well (i would get about 1kw out of a £1k turbine pretty consistently as it is quite gusty by us - but that would chip in day and night, which is a nice idea)
Anyway, i'll open this chat up to the floor.....
For some reason i use an outrageous amount of electricity at home (about 1000 kw/month with no electric cars atm... so that will increase when i get another electric car at some time in the future)
anyway, i have decided to get a PV array and battery storage to assist in operating with greater efficiency.
The spec is somewhat limited by western power limiting our feedback to around 5kw as we only have single phase and no practical opportunity to upgrade (the pole at the end of the drive is only single phase - i'm scared to even ask about the upgrade cost.....)
i'm still at an extremely early stage so the proposed spec is still fluid, but it's looking like C. 15kw pv and about 10 KWh battery
Anyway.....
for those who are more knowledgeable than me, what lessons have you learned from your own PV/battery setup that you would like to pass on.
are there any traps i need to be aware of, hints and tips etc.
i intend to change my electricity tariff so i can charge the batteries in the dead of night if necessary at a cheaper rate if there is no sun the day before.
would it be sensible to put a small wind turbine up as well (i would get about 1kw out of a £1k turbine pretty consistently as it is quite gusty by us - but that would chip in day and night, which is a nice idea)
Anyway, i'll open this chat up to the floor.....
Maybe more for homes and gardens... but it is something I have been podering too.
Usage here is about 750kWh per month, so a bit less than yours. No electric cars here either yet.
I have switched to Octopus and are about to get a meter installed so we can see the usage patern over the day. Signed up with Octopus Go initially as we should get 5p rate for 4 hours overnight. Once setup I shall compare with their Agile tariff. You do get negative pricing times, but having crunched the numbers from last year's figures, I see they are rare - I think only a few hours a year where you get paid for using power.
Was looking at an SMA inverter, and custom building a 12kWh battery array.
In theory, you can cut the bill by around 2/3 with sufficient storage.
PV doesn't seem to stack up - even if you do a self install, the payback seems to be a very long time.
Still at the investigating and data gathering stage.
Interested in others findings.
Usage here is about 750kWh per month, so a bit less than yours. No electric cars here either yet.
I have switched to Octopus and are about to get a meter installed so we can see the usage patern over the day. Signed up with Octopus Go initially as we should get 5p rate for 4 hours overnight. Once setup I shall compare with their Agile tariff. You do get negative pricing times, but having crunched the numbers from last year's figures, I see they are rare - I think only a few hours a year where you get paid for using power.
Was looking at an SMA inverter, and custom building a 12kWh battery array.
In theory, you can cut the bill by around 2/3 with sufficient storage.
PV doesn't seem to stack up - even if you do a self install, the payback seems to be a very long time.
Still at the investigating and data gathering stage.
Interested in others findings.
i've not thought about it like that, but you are of course right. you have to price the PV savings against the opportunity cost of nighttime rate, ie 5p/kwh which for a 15kwh array providing 13500 kw/annum gives a £675 saving/year.
I suppose the limitation is how quickly you can 'dump' electricity into the batteries during the golden few hours in the middle of the night will effectively give you your upper storage limit. the price of additional batteries is pretty minimal really. If you end up maxing out your overnight charging capacity, then you are back to daytime pv charging @15p which brings the payback back to sensible levels.
you can tell i'm not overly technical, lol...
I suppose the limitation is how quickly you can 'dump' electricity into the batteries during the golden few hours in the middle of the night will effectively give you your upper storage limit. the price of additional batteries is pretty minimal really. If you end up maxing out your overnight charging capacity, then you are back to daytime pv charging @15p which brings the payback back to sensible levels.
you can tell i'm not overly technical, lol...
We have a 4kW PV array, no battery.
We find that very little is "spare" even in the summer. All our export is diverted to hot water, if needed. For 6 months of the year we export nothing at all, and for three of those months we'd be having very cold showers if we were relying on it. On peak sunny days in summer, we export a few kW/h a day - all of the machines in the house are set to come on during the day (completely the opposite from the old Economy 7....), and once we've made hot water there isn't a lot left.
So I suppose the moral of the story is that you'll absorb 4kW easily, and you will only have an 8 kW array (really) to charge the battery. In the winter, it won't charge at all. In the summer, it will charge easily. Payback for the 4 kW array (with FIT) has been easy - done it in 5 years.
I can't make the maths for batteries add up at all. The only reason we'd do it is power cut protection - we're rural, and there are lots of breakages every year between us and the power station.
We find that very little is "spare" even in the summer. All our export is diverted to hot water, if needed. For 6 months of the year we export nothing at all, and for three of those months we'd be having very cold showers if we were relying on it. On peak sunny days in summer, we export a few kW/h a day - all of the machines in the house are set to come on during the day (completely the opposite from the old Economy 7....), and once we've made hot water there isn't a lot left.
So I suppose the moral of the story is that you'll absorb 4kW easily, and you will only have an 8 kW array (really) to charge the battery. In the winter, it won't charge at all. In the summer, it will charge easily. Payback for the 4 kW array (with FIT) has been easy - done it in 5 years.
I can't make the maths for batteries add up at all. The only reason we'd do it is power cut protection - we're rural, and there are lots of breakages every year between us and the power station.
We have 4KW PV panel on our house installed by previous owners, we do about 15k miles a year in our EV which is charged 95% of the time at home, and had a Tesla Powerwall installed in November.
Biggest obvious point, install the solar PV panels on a South facing roof, for some reason despite having loads of South facing roof space our panels are installed split between East/West facing, as an result when the sun is shinning the most our solar generation takes a nose dive......In summer it might be better as the sun will be higher.
Unless you are planning a massive array (15KW is big), you aren't going to generate enough to meet your usage. In December our solar panels generated a pathetic 50kWh versus home use of nearly 1000kWh.
'Loading shift' using a battery to help reduce costs only save you a small amount of money. Our Powerwall holds 13kWh usable, day time electricity is 15p per kWh, night 8p per kWh. Assume we cycle the battery every day 100%, so shift 13kWh a day to cheap electricity. Thats a theoretical max saving of £27 per month.
A Powerwall is £8k installed, it would take 25 years to break even from load shifting. I love the tech, it's amazing, but not sure I could justify paying for one out of my own pocket!
The pay back from FIT is a different matter, despite the oddly placed 4KW solar PV, we get a cheque for roughly £500/year from FIT. But FIT had now stopped so its an academic calculation for any one installing solar PV now.
Biggest obvious point, install the solar PV panels on a South facing roof, for some reason despite having loads of South facing roof space our panels are installed split between East/West facing, as an result when the sun is shinning the most our solar generation takes a nose dive......In summer it might be better as the sun will be higher.
Unless you are planning a massive array (15KW is big), you aren't going to generate enough to meet your usage. In December our solar panels generated a pathetic 50kWh versus home use of nearly 1000kWh.
'Loading shift' using a battery to help reduce costs only save you a small amount of money. Our Powerwall holds 13kWh usable, day time electricity is 15p per kWh, night 8p per kWh. Assume we cycle the battery every day 100%, so shift 13kWh a day to cheap electricity. Thats a theoretical max saving of £27 per month.
A Powerwall is £8k installed, it would take 25 years to break even from load shifting. I love the tech, it's amazing, but not sure I could justify paying for one out of my own pocket!
The pay back from FIT is a different matter, despite the oddly placed 4KW solar PV, we get a cheque for roughly £500/year from FIT. But FIT had now stopped so its an academic calculation for any one installing solar PV now.
Greg_D said:
Hi All,
For some reason i use an outrageous amount of electricity at home (about 1000 kw/month with no electric cars atm... so that will increase when i get another electric car at some time in the future)
That is ALOT of electricity consumption.For some reason i use an outrageous amount of electricity at home (about 1000 kw/month with no electric cars atm... so that will increase when i get another electric car at some time in the future)
Most of our home electricity usage is now from the Powerwall - charged at night. So out of the 1000kWh total electricity usage, 3/4 of that is for the EV.
By the time you take into account charging losses, pre heating etc, 2 miles per kWh is sensible guess for the EV. So 2x750 is 1500 miles roughly inline with our actual mileage.
However electricity really is cheap, £85/month all in plus standing charge. That would barely get me 300 miles with Ron 98 fuel in my old 335i.
gangzoom said:
We have 4KW PV panel on our house installed by previous owners, we do about 15k miles a year in our EV which is charged 95% of the time at home, and had a Tesla Powerwall installed in November.
Biggest obvious point, install the solar PV panels on a South facing roof, for some reason despite having loads of South facing roof space our panels are installed split between East/West facing, as an result when the sun is shinning the most our solar generation takes a nose dive......In summer it might be better as the sun will be higher.
.
Where are you - I've looked at my metrics and on that day we netted 9.5 kWh (Berkshire). Ours are SE and SW facing. It's actually good to have a mixture of directions because you get a better "distribution" of power in the day - but not E and W if you have the option of S!Biggest obvious point, install the solar PV panels on a South facing roof, for some reason despite having loads of South facing roof space our panels are installed split between East/West facing, as an result when the sun is shinning the most our solar generation takes a nose dive......In summer it might be better as the sun will be higher.
.
That was a good day for Jan - 2 days later on the 23rd we got 0.5 kWh for the whole day.
Peak summer is about 26 kWh.
^We are in Leicester, no idea why the original house owners didn't put the panels on the S facing roof. But the panels were never factored into the house price and we are now getting the about £500/year FIT payments so cannot complain.
We are hopefully going to be doing some major work to the roof of the house, so will move the west facing panels to south facing roof.
We are hopefully going to be doing some major work to the roof of the house, so will move the west facing panels to south facing roof.
The roof on our place is cruciform in plan, the largest areas facing slightly west of south. I had panels put on the small east-ish and west-ish facing surfaces as well as the main south-ish surfaces and it helps spread the output really well throughout the day. Grabs a reasonable amount from the west facing panels in the summer.
A 5.9kWp array, Evesham area,
The two strips of 3 panels are on the 'odd' roof faces. The set of 2 are on the main face, but somewhat masked by the 'south wing'
Given the small size of the roof, I reckoned it was worth adding the extra panels to make use of the maximum possible area, within the sensible output limits of the network provider (i.e. not having to get too involved).
We have a PW2 as well - jury out on if it'll ever be worth it TBH. The figures suggested a shorter payback period based on more self-consumption - it's early days yet as it's only been in just over 2 years.
A 5.9kWp array, Evesham area,
The two strips of 3 panels are on the 'odd' roof faces. The set of 2 are on the main face, but somewhat masked by the 'south wing'
Given the small size of the roof, I reckoned it was worth adding the extra panels to make use of the maximum possible area, within the sensible output limits of the network provider (i.e. not having to get too involved).
We have a PW2 as well - jury out on if it'll ever be worth it TBH. The figures suggested a shorter payback period based on more self-consumption - it's early days yet as it's only been in just over 2 years.
Edited by Chris-S on Saturday 1st February 09:33
Edited by Chris-S on Saturday 1st February 09:36
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