Suggestion needed for a Battery Backup System

saayinla

Hi All,

Given the rising energy prices, I have been looking at ways to reduce ongoing cost. I live in a 5 bedroom property with 3 adults and 4 teenagers. Our electricity usage is about 20-26KW daily. Both adult work from home and at least 1 adult will always work from home .

I was planning a DIY battery backup option, but then I realised if I can get Octopus Go tarriff to charge at night (planning to get EV also), then I can do without panels at least for now, save the money for panels and put it towards Batteries. I can buy 6 x Pylon 3.5kWh US3000C Li-Ion Battery - 48V Lithium (Total:£6,594.00) from Bumble Solar  to get 21KWH of battery storage which is about my daily usage. will cost me just about £1.50 effectively saving me at least £4 daily, going by Octopus Go Tariff.

Seeing as the Pylon Batteries are modular and not much to them, what kind of cost should I be looking at for installation plus inverter.

Thanks in advance.

Edit:-  Since the start of this Thread, I have now reconsider going battery alone from the start and looking to add about 4KW of panels so that charging will partly be done in the 4 hour window of Octopus Energy, because I have a Single Phase meter I am not sure I can charge faster than 7WK, but hopefully I will use part Solar to charge the battery prior.

Solarchaser

I'd say honestly if you have someone at home all day, yeah batteries will help, but solar will be much quicker to pay you back.

Perhaps worth getting quotes for solar with a hybrid inverter and then you can plug the pylontech on when it's all installed.

Anyway an inverter without solar will probably be about £800, something like the lux 3600 acs and then maybe £4-500 for installation,  but it very much depends on the local installers in your area.

Also worth noting that even if you have batteries enough to cover your home usage in a day, you will still import some electricity in peak times, things like having a washing machine and tumble dryer etc in at the same time will potentially use more than the 3.6kw of an ac inverter.

94JDH

saayinla said:

Hi All,

Given the rising energy prices, I have been looking at ways to reduce ongoing cost. I live in a 5 bedroom property with 3 adults and 4 teenagers. Our electricity usage is about 20-26KW daily. Both adult work from home and at least 1 adult will always work from home .

I was planning a DIY battery backup option, but then I realised if I can get Octopus Go tarriff to charge at night (planning to get EV also), then I can do without panels at least for now, save the money for panels and put it towards Batteries. I can buy 6 x Pylon 3.5kWh US3000C Li-Ion Battery - 48V Lithium (Total:£6,594.00) from Bumble Solar  to get 21KWH of battery storage which is about my daily usage. will cost me just about £1.50 effectively saving me at least £4 daily, going by Octopus Go Tariff.

Seeing as the Pylon Batteries are modular and not much to them, what kind of cost should I be looking at for installation plus inverter.

Thanks in advance.

I initially looked at this for the same reason, did some further research and realised combining solar with batteries will be more economical in the long run - same as your first reply above.
Although I'm going to be spending more initially the payback should be much better, however over how long depends on the pricing of electric.

arty688

Also if you add solar you will be charged 5% vat, with a budget of £7.5k ish you should be able to get a mix of solar and batteries which would save you more than just batteries.But it depends on what roof you have.

Also is that 20-26Kwh and average over the year or is it 20 in the summer and 26 in the winter ?

You will not be able to use the whole battery , not sure what the DOD is if that one.

and you will need an inverter that will charge 21.4kwh of batteries in 4 hours

There are also losses to take into account of maybe 15 to 20%.

Unfortunately the calculations are more complicated when it comes to ROI.











5

[Deleted User]

arty688 said:

Also if you add solar you will be charged 5% vat…

VAT on solar panels was increased to 20% in 2019. This blog explains how it is still possible to reduce the VAT down to 5%:

https://blog.spiritenergy.co.uk/homeowner/get-5-vat-solar-panels

saayinla

Solarchaser said:

I'd say honestly if you have someone at home all day, yeah batteries will help, but solar will be much quicker to pay you back.

Perhaps worth getting quotes for solar with a hybrid inverter and then you can plug the pylontech on when it's all installed.

Anyway an inverter without solar will probably be about £800, something like the lux 3600 acs and then maybe £4-500 for installation,  but it very much depends on the local installers in your area.

Also worth noting that even if you have batteries enough to cover your home usage in a day, you will still import some electricity in peak times, things like having a washing machine and tumble dryer etc in at the same time will potentially use more than the 3.6kw of an ac inverter.

Thank you so much for the insight and input, thinking about it based on the responses form everyone, I think it does make sense to go Solar from the start and then add batteries as time goes by. I ll probably be looking at a higher Capacity Inverter as we sometimes have the kettle, toaster and fryer going at the same time albeit for a short time. 

94JDH said:

I initially looked at this for the same reason, did some further research and realised combining solar with batteries will be more economical in the long run - same as your first reply above.
Although I'm going to be spending more initially the payback should be much better, however over how long depends on the pricing of electric.

Yes I have realised this after taking your comments into consideration, make sense for me to spend more upfront the payback time will be much quicker.. my energy tarriff is increasing originally from 13.2p to 20.7p now and then to 30p+ in April. so the earlier the better I can start reaping some savings. and the weather is looking amazing already!

arty688 said:

Also if you add solar you will be charged 5% vat, with a budget of £7.5k ish you should be able to get a mix of solar and batteries which would save you more than just batteries.But it depends on what roof you have.

Also is that 20-26Kwh and average over the year or is it 20 in the summer and 26 in the winter ?

You will not be able to use the whole battery , not sure what the DOD is if that one.

and you will need an inverter that will charge 21.4kwh of batteries in 4 hours

There are also losses to take into account of maybe 15 to 20%.

Unfortunately the calculations are more complicated when it comes to ROI.











5

There is only one part of my Roof that is south facing and I ll be limited to putting solar on just that bit, I nned to get survey done to determine my roof space so I can have an idea how many panels will fit, will prob be looking at 390W+ capacity panels to make full use of the roof space.

[Deleted User] said:

arty688 said:

Also if you add solar you will be charged 5% vat…

VAT on solar panels was increased to 20% in 2019. This blog explains how it is still possible to reduce the VAT down to 5%:

https://blog.spiritenergy.co.uk/homeowner/get-5-vat-solar-panels

Thanks, interesting info on their. Much appreciated.

arty688

Dolor said:

VAT on solar panels was increased to 20% in 2019. This blog explains how it is still possible to reduce the VAT down to 5%:

https://blog.spiritenergy.co.uk/homeowner/get-5-vat-solar-panels

In theory yes its 20% but everybody works the quotes to be 5% so in practice 5%

arty688

Also you roof doesn't have to be south facing. East and west are also good in fact can be better as they extend the generating hours in the day.

Dave_Fowler

You'd have to take a serious amount of energy from the mains to charge a 21kWh bank of batteries using the Octopus GO tariff.  The GO tariff is only 4 hours.  You would also need to have sufficient charging capability from your chosen inverter(s).  The GO FASTER tariff has a longer off peak time but it would still require a high charging rate.

94JDH

Dave_Fowler said:

You'd have to take a serious amount of energy from the mains to charge a 21kWh bank of batteries using the Octopus GO tariff.  The GO tariff is only 4 hours.  You would also need to have sufficient charging capability from your chosen inverter(s).  The GO FASTER tariff has a longer off peak time but it would still require a high charging rate.

Quite correct, I'm going for a 7.2kW solar system with two hybrid 3.6kW inverters and two 8.2kW batteries. This gives me the option of fully charging from the grid in the 4 hour period and also 5kW discharge from them as and when required.

Solarchaser

Dave_Fowler said:

You'd have to take a serious amount of energy from the mains to charge a 21kWh bank of batteries using the Octopus GO tariff.  The GO tariff is only 4 hours.  You would also need to have sufficient charging capability from your chosen inverter(s).  The GO FASTER tariff has a longer off peak time but it would still require a high charging rate.

It's not as bad as you may think.
I use go faster 3 hours.
I have 2x lux3600 parallel, they fill up nicely within the 3 hours. 

However you would certainly struggle to do more than 3.5kw an hour on one inverter