Watt am I doing?
New Member
Hi there all, I'm new here! (sorry for the long post)
I have 0 experience in DIY electronics or solar power, only basic installing new sockets & lights1
I would like to go fully off-grid eventually, but I am not looking to be silly with money - I think a 10% average return over 3-5 years would be reasonable, but otherwise not really feasible, so I am looking to install a system in stages (ensuring parts are suitable for future improvements)
Since doing the entirety in one go is not really feasible, and since I live in the UK with Octopus Energy, the first logical step seems to be to utilise the £0.075/kWh "Intelligent" tarriff (night rate) which lasts 6 hours to charge a battery, then utilise the battery during the day.
For reference, my house uses roughly 25 kWh per day.
Fogstar appear to offer a 30 kWh solution
Considering 6 hours overnight can be grid-tied on the night tarriff, 30kWh seems to be enough to cover the daily usage plus reserve.
My first thought was that the fogstar battery seems reasonable, all-in-one system with BMS built in...
Looking on alibaba though, this could potentially built for <£3000 so I am debating whether the extra £3000 is worth the time and chance of screwing up
Lets assume using the fogstar battery for now, which I think would be a negative yield over 5 years
UK mains single phase is 240V 100A according to the fuse
According to the battery on fogstar, the max discharge rate is 48V 600A, so converted this would be 240V ~120A (minus conversion losses)
I believe the 1C means it can charge at the maximum discharge rate? If we have 6 hours in which to charge the battery, it could therefore charge at a mains rate of 240V 21A (plus conversion losses) so we don't need to get close to that rate for charging.
I reckon that I spend £200/month although this varies quite a bit. Using only the standing charge of ~£0.59/day and the night rate of £0.075/kWh for 30kW, that would work out at £85/month + EV charging, maybe £25/month so £110/month meaning a reduction of £90/month or £5400 over 5 years, now this is not factoring in potential rises in price (which seem likely) or the removal of this tarriff - at which point I would be looking to entirely break with the grid.
Key points:
I have a few questions which I would really appreciate your support with:
1) Aside from the fogstar battery, which includes a BMS, what other components would be needed to tie this into my home system with instant grid-switch? (I do not want to feedback to the grid)
2) Does this look feasible?
3) If I was to go with the alibaba batteries & the same BMS that fogstar uses, are there any other considerations than wires, busbars & a case that would be required?
4) In future, what additional components would be needed to go completely off-grid (aside from panels, turbines, more batteries & their fixings/mountings/cables)? (I do not want to feedback, excess will be burned off more efficiently)
I have 0 experience in DIY electronics or solar power, only basic installing new sockets & lights1
I would like to go fully off-grid eventually, but I am not looking to be silly with money - I think a 10% average return over 3-5 years would be reasonable, but otherwise not really feasible, so I am looking to install a system in stages (ensuring parts are suitable for future improvements)
Since doing the entirety in one go is not really feasible, and since I live in the UK with Octopus Energy, the first logical step seems to be to utilise the £0.075/kWh "Intelligent" tarriff (night rate) which lasts 6 hours to charge a battery, then utilise the battery during the day.
For reference, my house uses roughly 25 kWh per day.
Fogstar appear to offer a 30 kWh solution
Fogstar Energy 30kWh 48V Rack Battery Bundle
30kWh 48v Rack Battery Lithium (LiFePO4) heating, pre-loaded inverter protocols, LCD touch screen, Grade A EVE Cells, a DC Rated Breaker and an 8 year warranty.
www.fogstar.co.uk
Considering 6 hours overnight can be grid-tied on the night tarriff, 30kWh seems to be enough to cover the daily usage plus reserve.
My first thought was that the fogstar battery seems reasonable, all-in-one system with BMS built in...
Looking on alibaba though, this could potentially built for <£3000 so I am debating whether the extra £3000 is worth the time and chance of screwing up
Eve Lf280k 8000cycles 3.2v Lithium Cells Lifepo4 320ah Eve 280ah Grade A 32v Rechargeable Battery Lifepo4 Batteries - Buy Eve 280ah Lifepo4 Lfp 32v Cells Battery lifepo4 320ah Battery Trade lifepo4 100ah 32v Product on Alibaba.com
Eve Lf280k 8000cycles 3.2v Lithium Cells Lifepo4 320ah Eve 280ah Grade A 32v Rechargeable Battery Lifepo4 Batteries - Buy Eve 280ah Lifepo4 Lfp 32v Cells Battery lifepo4 320ah Battery Trade lifepo4 100ah 32v Product on Alibaba.com
www.alibaba.com
Lets assume using the fogstar battery for now, which I think would be a negative yield over 5 years
UK mains single phase is 240V 100A according to the fuse
According to the battery on fogstar, the max discharge rate is 48V 600A, so converted this would be 240V ~120A (minus conversion losses)
I believe the 1C means it can charge at the maximum discharge rate? If we have 6 hours in which to charge the battery, it could therefore charge at a mains rate of 240V 21A (plus conversion losses) so we don't need to get close to that rate for charging.
I reckon that I spend £200/month although this varies quite a bit. Using only the standing charge of ~£0.59/day and the night rate of £0.075/kWh for 30kW, that would work out at £85/month + EV charging, maybe £25/month so £110/month meaning a reduction of £90/month or £5400 over 5 years, now this is not factoring in potential rises in price (which seem likely) or the removal of this tarriff - at which point I would be looking to entirely break with the grid.
Key points:
- Grid-to-battery instantaneous changeover i.e. would not affect a computer
- No interest in feeding back to grid
- Over a 24 hour period; battery must charge in 6 hours & cover 25kWh for the rest of the period
- Components should be future-proof against adding a high power solar (25kW) & wind system (10kW) for going off-grid eventually (more batteries in future)
I have a few questions which I would really appreciate your support with:
1) Aside from the fogstar battery, which includes a BMS, what other components would be needed to tie this into my home system with instant grid-switch? (I do not want to feedback to the grid)
2) Does this look feasible?
3) If I was to go with the alibaba batteries & the same BMS that fogstar uses, are there any other considerations than wires, busbars & a case that would be required?
4) In future, what additional components would be needed to go completely off-grid (aside from panels, turbines, more batteries & their fixings/mountings/cables)? (I do not want to feedback, excess will be burned off more efficiently)