DocD Posted February 4 Share Posted February 4 Hi everyone. I'm new to this site. What are your thoughts on a battery storage system with 5kw solis inverter and 15.5kwh seplos battery? Just want to utilise the cheap night tariffs to charge battery over night and use it during day. No solar panels. Look forward to comments on the hardware Thanks Link to comment Share on other sites More sharing options...
Dan F Posted February 4 Share Posted February 4 (edited) 13 minutes ago, DocD said: 15.5kwh seplos battery? Which battery? Do you have a U.K supplier? Have a look at https://www.fogstar.co.uk/collections/solar-battery-storage too. I have two 14.3kWh Seplos batteries, but using Victron. Allow me to use 7.5p electricty all day in the winter.. Edited February 4 by Dan F Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 Yes uk.. Fitter is advertising on ebay with 15.5kwh seplos battery. Are they reliable and good quality? Any issues? Thoughts on the solis inverter? Link to comment Share on other sites More sharing options...
AppleDown Posted February 5 Share Posted February 5 Have you done the calcs for ROI? Last time we did them it wasn’t worth the initial cost over the lifetime of the battery. Link to comment Share on other sites More sharing options...
Originaltwist Posted February 5 Share Posted February 5 Yes, ROI is challenging but if you have a heat pump to multiply the benefits then it heads into no-brainer territory. Link to comment Share on other sites More sharing options...
AppleDown Posted February 5 Share Posted February 5 1 hour ago, Originaltwist said: Yes, ROI is challenging but if you have a heat pump to multiply the benefits then it heads into no-brainer territory. I know it's subjective too. There's no ROI with plumbing or similar, so it gets down to whether it's something you can live with or without. Yes, if you've got the threat of power outages, you live off-grid, or you have a brilliant deal with your electrical supplier (export and night tariffs) then it's worth it in my eyes. But if you want it because you think it's going to help lower your bills significantly (and it's a cool bit of tech) then I don't think we're there yet. Link to comment Share on other sites More sharing options...
RobLe Posted February 5 Share Posted February 5 I have a 3.6kW sunsynk inverter + 15.5kWh Seplos battery (from fogstar). Building the battery was slow but easy, and I think should only be done by people with some electrical experience. It's so crucial not shorting stuff out! I got the vertical 280L battery - big recommend - it's got wheels! Once built, a 15kWh battery is insanely heavy, so wheels are very helpful. Only issue I noted was having to pack out the bottom myself to get good battery compression. We use 7.5p elecy always now too. Well - more like 7.5p/efficiency, and the round trip efficiency is 76% (round trip carefully measured AC-batt-AC averaged over 30 days with a mid certified meter), making it 9.9p/kWh. The sun is peeking out now, so it'll all be free soon! 1 Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 So I use around 20kwh electricity over 24 hours (when not charging my EV 5kwh off peak and 15kwh peak 15x30p = £4.50 daily = £1638 yearly 15x7.5p = £1.13 daily = £409.50 yearly Equates to £1230 saving per year If battery/inverter fees are £4500 for above system then just under 4yrs ROI If battery/inverter fees £6500 for pylontech instead of seplos then just over 5yrs ROI Battery life 6000 cycles so still should be good for a while (hope my calculations are correct!) Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 Next thing is about DNO. The electrician said no need to inform DNO as nothing is going back to the grid. Other companies are saying need to do an application for G99 Someone else said can just do G98 application Which is right? Link to comment Share on other sites More sharing options...
RobLe Posted February 5 Share Posted February 5 I think your electrician doesn't want to bother his a**e talking to the DNO. It doesn't matter if you do/will export - it matters if you can. So if that Solis inverter can export, then the DNO need to know - and if it's over 16A ACrms (which it sounds like it is), then you need to ask permission. If <=16A ACrms, then you just need to inform the DNO - hence a lot of inverters being rated at that limit rather than over it. Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 Thanks for explaining. Can a person like me who knows nothing about electricity apply? Or would the electrician need to? What would have happened if they installed without permission? Link to comment Share on other sites More sharing options...
Dan F Posted February 5 Share Posted February 5 £3k (if i found the round the right publication) for 15kWh battery, inverter, installation and DNO application is a bit too good to be true! Wouldn't be suprised it cutting some corners.. Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 49 minutes ago, Dan F said: £3k (if i found the round the right publication) for 15kWh battery, inverter, installation and DNO application is a bit too good to be true! Wouldn't be suprised it cutting some corners.. Been quoted £4500 installed Link to comment Share on other sites More sharing options...
Dan F Posted February 5 Share Posted February 5 1 hour ago, DocD said: Been quoted £4500 installed That makes more sense. Remember shouldn't be charged VAT now. As others have said, I'd avoid anyone that suggests you don't need a G99 application, you do. Link to comment Share on other sites More sharing options...
Jenki Posted February 5 Share Posted February 5 4 hours ago, DocD said: So I use around 20kwh electricity over 24 hours (when not charging my EV 5kwh off peak and 15kwh peak 15x30p = £4.50 daily = £1638 yearly 15x7.5p = £1.13 daily = £409.50 yearly Equates to £1230 saving per year If battery/inverter fees are £4500 for above system then just under 4yrs ROI If battery/inverter fees £6500 for pylontech instead of seplos then just over 5yrs ROI Battery life 6000 cycles so still should be good for a while (hope my calculations are correct!) Who supplies your power, your e7 rate is really low Link to comment Share on other sites More sharing options...
Dan F Posted February 5 Share Posted February 5 5 hours ago, DocD said: So I use around 20kwh electricity over 24 hours (when not charging my EV 5kwh off peak and 15kwh peak 15x30p = £4.50 daily = £1638 yearly 15x7.5p = £1.13 daily = £409.50 yearly Equates to £1230 saving per year If battery/inverter fees are £4500 for above system then just under 4yrs ROI If battery/inverter fees £6500 for pylontech instead of seplos then just over 5yrs ROI Battery life 6000 cycles so still should be good for a while (hope my calculations are correct!) Battery will do more than 6000 cycles, will just degredate in terms of usable capacity with use. The one assumption you are making is that you peak usage is never more than 21A (5kW). If you have peak usage above this, then you'll be pulling from the grid at 30p. BTW, do you have or plan to get PV too? Link to comment Share on other sites More sharing options...
Wil Posted February 5 Share Posted February 5 17 minutes ago, Jenki said: Who supplies your power, your e7 rate is really low Octopus Intelligent Go gives 7.5p from 23.30- 05.30 @Originaltwist are you the author of this website? https://originaltwist.com/2018/11/14/diy-fan-coil-heater/ Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 2 hours ago, Jenki said: Who supplies your power, your e7 rate is really low Octopus intelligent go tariff Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 2 hours ago, Dan F said: Battery will do more than 6000 cycles, will just degredate in terms of usable capacity with use. The one assumption you are making is that you peak usage is never more than 21A (5kW). If you have peak usage above this, then you'll be pulling from the grid at 30p. BTW, do you have or plan to get PV too? Not planning on getting PV. Don't want to risk anything on the roof. I'll be happy with 7.5p peak charges with battery. DNO just came back to me following my EV charger install last month.. Saying they will need to do fuse upgrade (currently 100amp) and also service cable replacement to cope with increased demand. Also they're saying I'm looped so will need to do neighbour as well 🤣😭. Lucky me 4 month wait. Looks like battery install might have to be delayed? Link to comment Share on other sites More sharing options...
Dan F Posted February 5 Share Posted February 5 10 minutes ago, DocD said: they will need to do fuse upgrade (currently 100amp) I thought 100A was max for residential supplies. 11 minutes ago, DocD said: Looks like battery install might have to be delayed? Not necesarily, you could get something G98 compliant and just install it. You don't need to ask for permission, just notify. Also, just because they want to reinforce supply, doesn't mean you'd necesarily have 5kW inverter denied. Link to comment Share on other sites More sharing options...
Cooeyswell Posted February 5 Share Posted February 5 18 hours ago, DocD said: Hi everyone. I'm new to this site. What are your thoughts on a battery storage system with 5kw solis inverter and 15.5kwh seplos battery? Just want to utilise the cheap night tariffs to charge battery over night and use it during day. No solar panels. Look forward to comments on the hardware Thanks I am in the process of self-installing just such a system. In my case the hardware is A Seplos Mason 280L (14.4 kWh, A-grade cells) £2156 A Solis RAI-3.0KW 48ES 5G AC Coupled Inverter £640 I don't have or plan to install PV. I will be using this system to shift the majority of my power usage onto E7. Just finished the wiring today, tomorrow is the big switch on Wish me luck Link to comment Share on other sites More sharing options...
Dan F Posted February 5 Share Posted February 5 3 minutes ago, Cooeyswell said: A Seplos Mason 280L (14.4 kWh, A-grade cells) £2156 Is the 280L the vertical one? I've got two of them. 3 minutes ago, Cooeyswell said: A Solis RAI-3.0KW 48ES 5G AC Coupled Inverter £640 Can't you go one size up with inverter? With 3kW inverter, you will only get cheap/e7 electricity if your consumption is below 3kW. Put the kettle/oven on, and you'll likely be paying peak rate.. Link to comment Share on other sites More sharing options...
Dillsue Posted February 5 Share Posted February 5 7 hours ago, DocD said: Thanks for explaining. Can a person like me who knows nothing about electricity apply? Or would the electrician need to? What would have happened if they installed without permission? Yes you can and its straight forward- download the form and see what info you need. You'll likely need to supply a single line diagram of your house distribution but Google it and you'll likely find something you can doctor. If you installed without permission, you'll be breaking the terms of your electricity supply contract and the national terms of connection which I think are legally enforceable. A G99 is straight forward so why would you want to not do the right thing. No ones going to check up on you unless there's a problem. If you go for a 3.68kw G98 inverter instead of the 5kw one, then all the G99 paperwork, and fee, go away but you'll likely be drawing on the grid more often than with a 5kw unit Link to comment Share on other sites More sharing options...
Cooeyswell Posted February 5 Share Posted February 5 30 minutes ago, Dan F said: Is the 280L the vertical one? I've got two of them. Can't you go one size up with inverter? With 3kW inverter, you will only get cheap/e7 electricity if your consumption is below 3kW. Put the kettle/oven on, and you'll likely be paying peak rate.. I did look at 5kW inverters, most of these seem to be hybrids and cost around £500 more. Bizarrely several 5kW hybrids will only provide/source 3k to the battery (Growatt). They also (as mentioned) require a G99 sign-off prior to the install along with payment. G98 is a lot simpler. I think this size gives the best "bang per buck" for my purposes. I am not attempting to cover all power consumption scenarios. From observation I expect to cover 80-90% of my peak usage with a 3kW system. Link to comment Share on other sites More sharing options...
DocD Posted February 5 Author Share Posted February 5 3 hours ago, Dan F said: I thought 100A was max for residential supplies. Not necesarily, you could get something G98 compliant and just install it. You don't need to ask for permission, just notify. Also, just because they want to reinforce supply, doesn't mean you'd necesarily have 5kW inverter denied. I don't know what's max for residential, but they email me today saying will need to upgrade/increase my fuse So the only issue with G98 compliant is that the inverter would be 3.68kw? I'm looking at my bill and most of the day I'm always less than 1kw usage. Only goes over 3kw when charging car at night. Maybe 3.68kw inverter will be ok for my needs Link to comment Share on other sites More sharing options...
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