Home Battery - No Solar

MerryChristmas

Looking at getting a home-battery installed to store economy7 electricity at night and use it during peak times.
I don't want to feed anything back into the grid. We will use it all.

Does anyone know what kit I'd require, and what the cheapest supplier / option would be?

We will attach a PV array to the battery at a later stage, but right now I reckon the cost it out of our reach, so just a battery to start.

We have an electric car that draws around 10kwh a night on Eco7. We also have an air source heat driven wet underfloor central hearting and hot water system.

The theory is a decent sized battery would help reduce our overall electricity costs immediately. Later on an additional PV array will mean we can reduce our reliance on the grid and reduce costs further still.

Any help much appreciated.

Thanks.

1961Nick

Hi MC,
When I installed batteries 3 months ago, the Pylontech US2000 Plus was the cheapest battery system on the market. I chose the Sofar ME3000SP inverter as it had software that recognised Pylontech batteries, thereby simplifying installation - other inverters are available. The modular nature of Pylontechs means that expansion is literally a 5 minute job with no setup necessary.

Batteries cost around £780 inc Vat if you're prepared to haggle.
Inverters are from £550 inc Vat with the aforementioned haggle.

Each battery has a capacity of 2.4kWh of which 85% is usable with the Sofar inverter. A software upgrade will eventually take that to 90% which is the maximum the battery will allow. Base your calculations on 2kWh per unit & you'll have an idea how many you will need.

There is also the Tesla PW2. The cost is higher but it has the advantage of a 5kWh discharge rate instead of the Sofar's 3kWh (with 3 or more batteries). That may or may not be important?

mmmmikey

Based on Internet research rather than personal expereince, I agree with 1961Nick if you're looking for the cheapest robust/sensible mainstream option the Pylontech/Sofar combination looks hard to beat (meaning that I'd steer clear of any unknown Chinese kit on eBay even if you can find it cheaper). The guy who just installed my PowerVault was of a similar view, and his business is based around servicing and maintaining these things rather than selling them so I would consider him a decent point of reference. Although I chose the PowerVault myself, that choice wasn't based on cost - you can see my reasoning on the battery thread.

As well as the inverter and battery, you'll need various sundry wiring bits, exactly what depends on what you have at the moment and how/where the batteries/inverter are connected in. I'd budget in the region of £300 for the cost of the electrician to do the work plus any bits needed, but this could vary quite a bit.

Also, as I understand it the Pylontech batteries are designed to be mounted in a rack so you may want to factor in something for the cost of that (guessing at £100 - anyone got an accurate price). This isn't essential, and if you're looking at minimising the cost I'm sure you could do something satisfactory yourself for very little cost if you've got time and DIY skills.

EricMears

MerryChristmas wrote: »

Looking at getting a home-battery installed to store economy7 electricity at night and use it during peak times.
....

The theory is a decent sized battery would help reduce our overall electricity costs immediately.

Suggest you look back through threads on this forum which dealt with batteries.

Whilst the idea of being able to buy all electricity at offpeak rates is attractive, those who'd done the maths reckoned that when you worked out how many charges & discharges you could expect before the battery stopped working, calculated what total kWh that would transfer and divided that into the (cost of the equipment + interest paid on loan to buy it or lost from a savings account) you'd get a storage cost/kWh which was bigger than the difference between E7 peak & offpeak rates !

i.e. although in the short term you could stop buying peak rate electricity, in the longer term your total costs would actually increase.

I don't have a battery and haven't done the calculations for myself.

1961Nick

EricMears wrote: »

Suggest you look back through threads on this forum which dealt with batteries.

Whilst the idea of being able to buy all electricity at offpeak rates is attractive, those who'd done the maths reckoned that when you worked out how many charges & discharges you could expect before the battery stopped working, calculated what total kWh that would transfer and divided that into the (cost of the equipment + interest paid on loan to buy it or lost from a savings account) you'd get a storage cost/kWh which was bigger than the difference between E7 peak & offpeak rates !

i.e. although in the short term you could stop buying peak rate electricity, in the longer term your total costs would actually increase.

I don't have a battery and haven't done the calculations for myself.

Some very good points here. I think it's fair to say that those that have installed batteries have done it knowing that the break even point is a long way in the future & beyond the 10 year warranty period of their batteries/inverter. Without solar the probability of breaking even is remote.

To have a chance of figuring out the payback period, we'd need to know...

~Total peak rate usage.
~Total off peak rate usage
~Peak rate usage during the winter months - relevant to battery sizing.
~Peak/off peak rate/kWh
~When & what size solar array is likely to be installed.