Soldato
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- 19 Oct 2010
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- 2,501
With super cheap electric it's less important. My PW2 is saving me 50p a day by not charging due to the sunny forecast. If overnight electric ever got more expensive that intelligence will be more valuable.
Solar panels and battery - any real world reccomendations?
- Thread starter GinG
- Start date
With super cheap electric it's less important. My PW2 is saving me 50p a day by not charging due to the sunny forecast. If overnight electric ever got more expensive that intelligence will be more valuable.
Quick question. We have been looking at solar panels for a while but I am still confused as to thew size of battery that we should get. For example, if we had a 5.07 kWp system (which the company estimate will produce 4046 kW/h per annum), what size battery do we need?
Is it a battery that can absorb the total panel output, or do we go larger and have one that can absorb unused output but also take Octopus Go overnight rates as well?
Is it a battery that can absorb the total panel output, or do we go larger and have one that can absorb unused output but also take Octopus Go overnight rates as well?
Solar array size is mutually exclusive, and you shoudl be looking to pair your battery with the energy you use when the sun isn't out. ie bigger battery that can be charged during day if you have excess or at night using cheaper rates.
Associate
Its very complicated. How much energy do you use, when do you use it, can you move it to benefit from when a battery is charged to use that as the source?
The battery can be as big or small as you want/need, the determining factor of how fast it can absorb energy from solar panels will be inverters, and their specs? If you went up to say a 10kW PV array, an inverter may still only charge the batteries at 3/4/5kW.
Basically, bigger is always better. More solar PV panels=more chance you'll generate significant energy in winter. Bigger battery (to I suppose about your daily/twice daily usage) so you can charge those batteries for free from solar or cheap overnight rates and then use it when the sun isnt out and its not cheap overnight. Bigger inverter ratings so you charge the batteries quicker with a big solar array, and can also supply the house with more power at once too.
The battery can be as big or small as you want/need, the determining factor of how fast it can absorb energy from solar panels will be inverters, and their specs? If you went up to say a 10kW PV array, an inverter may still only charge the batteries at 3/4/5kW.
Basically, bigger is always better. More solar PV panels=more chance you'll generate significant energy in winter. Bigger battery (to I suppose about your daily/twice daily usage) so you can charge those batteries for free from solar or cheap overnight rates and then use it when the sun isnt out and its not cheap overnight. Bigger inverter ratings so you charge the batteries quicker with a big solar array, and can also supply the house with more power at once too.
That's why for my system I've gone for 2 batteries and 2 inverters to maximize storage of 7.2kW array and also maximize the charge on night rate for winter periods. Additional benefits being 2x3.6kW discharge rate if demand from house needs it.
Associate
Very good solar weather last couple of weeks. The rental property with only a 3.5kw system, 19-31March inclusive(13days)
generated 209KW, really good for March and considering there is another good 6 months of solar generation.
2014 install date, receives FIT payments of just over 20p a unit, the 13 days have earned £42.
generated 209KW, really good for March and considering there is another good 6 months of solar generation.
2014 install date, receives FIT payments of just over 20p a unit, the 13 days have earned £42.
Soldato
Best March I've had since install in 2018, 427kWh from a 4.2kW system. Almost double my monthly household usage.
That's brilliant, can't wait for my install
Soldato
- Joined
- 19 Oct 2010
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Good numbers. Installed in 2012, I've a 4k PV into a 3k inverter, 402.9 last month.
Soldato
Third best March for me, 2022 was 390kWh, 2017 was 397kWh and the best 2020 was 430kWh, with a 4kw system.
Best month ever since install in December 2015 was May 2020 with 712.5kWh.
Best month ever since install in December 2015 was May 2020 with 712.5kWh.
I'm just going to wait it out - I've been recommended Fox ESS and Alpha smile on other quotes I've received.
I’ve got my installer coming around later to scope out the install. Will see what his views are.
Soldato
- Joined
- 19 Oct 2010
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2020 was crazy. That was the start of lockdown. That 3 month period was my best as well.
mar - 441
apr - 583
may - 708
Soldato
447kWh for our 6kWh system for the month of March. I cleaned our panels as the Sahara dust fall did lower the generation.
I hope that's not true -going to be a lot of disappointed customers.
Hi all, this thread has been super useful in my research, thank you. I'm wondering if anyone has any thoughts on my plans?:
We live in the SE near London, 6 bedroom house, south facing garden. Conventional gas HW and CH, we use about £1.50-£3 of electricity a day (can't provide annual estimates as haven't had a bill since Avro went bust last year, have been chasing...) Gas has been about £3-7/day through this winter.
I would like to use the immersion via Iboost or similar to reduce gas useage but I'll look into that once I have an idea of what I am feeding back to the grid. We'd go on the Octopus Go tariff and I would force charge the batteries overnight when PV fails to fill them. We are about to order an EV which will live at home during the day most of the time so I could trickle charge that off the PV but I doubt there will be any power left after the house and immersion demand so that will probably be set on the cheap 4 hour overnight GO rate.
We are close to pulling the trigger on this system:
The SolarEdge system and the need it creates for a seperate charge controller is adding about £2,500 to the price, the issue is that I have dormers and and trees about.
South Array
Proposed System Rating ( kWp ) 2.77 kWp
Postcode Region Region 1
Array Orientation S/E 0 Degrees
Pitch of Mount 35 Degrees
Over Shading Factor Factor 0.95
Estimated Solar Radiation 934 kWh / Annum
Estimated Annual System Output Using MCS Standard Procedure 2,587 kWh / Annum
West Array
Proposed System Rating ( kWp ) 2.77 kWp
Postcode Region Region 1
Array Orientation S/E 90 Degrees
Pitch of Mount 35 Degrees
Over Shading Factor Factor 1.0
Estimated Solar Radiation 783 kWh / Annum
Estimated Annual System Output Using MCS Standard Procedure 2,169 kWh / Annum
I am having some second thoughts on the cost vs my current annual electricity useage which isn't all that much.
House is about as well insulated as is possible for a 1980s home that has been retrofitted (cavity wall insulation, 50mm kingspan added above ground floor beam and block 150mm kingspan in roof.
I would welcome all and any comments, thanks very much.
We live in the SE near London, 6 bedroom house, south facing garden. Conventional gas HW and CH, we use about £1.50-£3 of electricity a day (can't provide annual estimates as haven't had a bill since Avro went bust last year, have been chasing...) Gas has been about £3-7/day through this winter.
I would like to use the immersion via Iboost or similar to reduce gas useage but I'll look into that once I have an idea of what I am feeding back to the grid. We'd go on the Octopus Go tariff and I would force charge the batteries overnight when PV fails to fill them. We are about to order an EV which will live at home during the day most of the time so I could trickle charge that off the PV but I doubt there will be any power left after the house and immersion demand so that will probably be set on the cheap 4 hour overnight GO rate.
We are close to pulling the trigger on this system:
- PV: 14x JA Solar 395w Percium Half-Cell All Black
- Optimisers: 14x Solar Edge S500
- Inverter: Solar Edge 3.68 HD Wave
- Bird Prevent Mesh (+£750 :s damn wood pigeons!)
- Charge Controller: Solis 3.0 RAI AC coupled
- Storage: 2x Pylontech US3000 3.5kWh Li-Ion Battery
The SolarEdge system and the need it creates for a seperate charge controller is adding about £2,500 to the price, the issue is that I have dormers and and trees about.
South Array
Proposed System Rating ( kWp ) 2.77 kWp
Postcode Region Region 1
Array Orientation S/E 0 Degrees
Pitch of Mount 35 Degrees
Over Shading Factor Factor 0.95
Estimated Solar Radiation 934 kWh / Annum
Estimated Annual System Output Using MCS Standard Procedure 2,587 kWh / Annum
West Array
Proposed System Rating ( kWp ) 2.77 kWp
Postcode Region Region 1
Array Orientation S/E 90 Degrees
Pitch of Mount 35 Degrees
Over Shading Factor Factor 1.0
Estimated Solar Radiation 783 kWh / Annum
Estimated Annual System Output Using MCS Standard Procedure 2,169 kWh / Annum
I am having some second thoughts on the cost vs my current annual electricity useage which isn't all that much.
House is about as well insulated as is possible for a 1980s home that has been retrofitted (cavity wall insulation, 50mm kingspan added above ground floor beam and block 150mm kingspan in roof.
I would welcome all and any comments, thanks very much.
Yes they have, 0 VAT on there.
This is the output of the estimate on the energy saving trust website. It doesn't factor in the battery's role:
Potential annual benefit£545
Potential CO2 saving982 kg / year
Potential fuel bill saving£433 / year
Potential payments from SEG
(at 4.1 p/kWh)£112 year
Potential lifetime benefit£13,190
This is the output of the estimate on the energy saving trust website. It doesn't factor in the battery's role:
Potential annual benefit£545
Potential CO2 saving982 kg / year
Potential fuel bill saving£433 / year
Potential payments from SEG
(at 4.1 p/kWh)£112 year
Potential lifetime benefit£13,190