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Energy Storage

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batalto

(@batalto)

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Topic starter 02/12/2021 9:25 am

I am looking at beefing up my battery storage as the ASHP loves power, my solar is big and I have a cheaper overnight tariff.

I've been reviewing batteries and settled on the Seplos Pusung 5kw batteries - https://www.seplos.com/sale-14177418-pusung-s-stackable-household-lithium-48v-100ah-lifepo4-10kwh-off-grid-3kwh-5kw-battery-power-home-so.html

They are LiFePO4, so very stable, they have good storage, 5kw and they can charge/discharge at 100A@51v so 5kw peak in and out. They are also stackable, so I could get 2 and have 10kw etc.

I've also spoken to them and they've told me its $2100 (£1500) per unit for 1, $1800 (£1325) per unit for 6, and $1200 (£900) per unit for 12 plus $350 USD shipping per battery to the UK. If I get them in a big order, it works out very reasonable from a good supplier. I will also need a 5kw hybrid inverter, and this will be £600-£1000

My question is... is anyone else thinking about batteries? If you are, would you consider a bulk order to lower the costs? Using Octopus Go, I could realistically charge 20kW overnight at 5p/kW

12kW Midea ASHP - 8.4kw solar - 29kWh batteries
262m2 house in Hampshire
Current weather compensation: 47@-2 and 31@17
My current performance can be found - HERE
Heat pump calculator spreadsheet - HERE

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George

(@george)

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02/12/2021 10:26 am

One thing to note would be if Octopus goes under or removes the Go tariff you would be left with a system that would only really work in summer provided you can fill all the batteries with excess solar and have expensive batteries doing nothing in winter.

Mitsubishi Ecodan 14kw ASHP + 500l Cylinder

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batalto

(@batalto)

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Topic starter 02/12/2021 11:18 am

@george there are plenty of other time of day tariffs and EV tariffs from many major firms. Currently my 14kw batteries provide 32% of all my power use. If you can buy them at the right price they make better financial sense than solar panels - which only work when the sun shines and if you don't use the power you give it away to the network operator

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MattEngineer

(@mattengineer)

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03/12/2021 6:37 pm

I’ve been seriously looking at battery storage, had a quote for Huawei 10kw and 19 405w panels at £14k. Just about to point out to the solar company that the panels won’t fit. There is a market for a decent national solar company.

what inverter are you planning on using?

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batalto

(@batalto)

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Topic starter 03/12/2021 6:42 pm

@mattengineer I've got a Sofar 3000 however that only charges/discharges at 3kw. Ideally I'd like 5kw to take full advantage. Then I'd have 8kw peak capacity. Also if I went 25kw I'd only get 20kw of storage at 80% DoD so I'd need 5kw to fill it at 5p octopus go

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MattEngineer

(@mattengineer)

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03/12/2021 7:12 pm

@batalto Are you able to parallel two sofar inverters? Giv energy ac coupled inverters can be paralleled (up to 3) but the ramp up of house loads takes a while (c15 secs) so you’re still drawing off the grid.

I’ve got two 80 amp supplies(in phase) coming in to the house, annoyingly western power wanted over £10k to upgrade to full 3 phase which would have been great for inverter choice and ev chargers etc. That could be 4 hours at 80a x 240v could be 153.6kw just need some grid scale batteries. (Wonder if they sell them 2nd hand).

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batalto

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Topic starter 03/12/2021 8:03 pm

@mattengineer yes from what I've seen you can have up to 3 in parallel.

You would 100% need grid scale batteries. Most inverters take batteries up to 52v at 100A (so 5kw). However they are usually limited less. It's all about the wire sizes as you would know as well as other things.

I looked at 3 phase - they wanted £5k to bring it across the road. Should have bought a house on the other side!

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MattEngineer

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05/12/2021 3:25 pm

@batalto Curious western power gave me a similar explanation (excuse) that they would need to upgrade the whole ABC from the transfer on the other side of the road.

If I had the time I would build a 16 prismatic cells (280ah) in series to give a 51.2v nominal battery c11.5kw at 80% depth of discharge.