Great topic… I was actually going to ask something similar myself. The Powerwall (our neighbour has one) is fairly idiot-proof, which definitely has its appeal (despite its cost), but I’m really interested to hear what other options people are running and how they’re getting on with them. I known there’s a lot of threads on the go along similar lines, but it’d be good to discuss pure ease of use, installation and costs here.

Beyond simple ROI, which is obviously easier to achieve with cheaper, semi- or unbranded kit that isn’t always the most user-friendly, two things really stand out for me: how much storage you actually need and whether the system can properly “island” during an outage.

Taking heating and the heat pump out of the equation entirely, our base load sits just under 1 kWh. To keep the maths simple, call it 1 kWh an hour to run fridges, electronics, lighting, our home sewage treatment plant, etc. We both work from home, so that load is fairly constant.

In a prolonged power cut like the one we’ve just had, that means we’re looking at around 24 kWh of usable storage just to get through a day. PV might top that up a little, and yes, you could conserve by cutting lighting and non-essentials, but it’s still a lot of battery capacity, which means space, complexity and cost.

That’s why I’m really keen to hear what others are doing, especially around resilience rather than just payback. Grid reliance, outages and energy security feel like they’re going to become much bigger conversations in the months and years ahead.

FWIW I started a thread here  just a few days ago trying to understand the options for islanded (ie able to operate when grid disconnected) and non islanded systems.  This was quite technical and currently totals 11 pages.  It  turned into a deep discussion of earthing arrangements (which are rather important).  Suffice it to say its not trivial particularly if, like me, you also have solar with a FIT tariff which thus needs a separate generation meter. 

I haven't yet reached a conclusion but the viability (for me) rests on combining the work to install the battery with a CU upgrade that is anyway well overdue and doing the whole thing as one job.  This runs into the problem that the battery inverter people tend to be specialists and its as yet unclear to me where I can draw the line between a general electrician to do the bulk of the work, and a battery inverter specialist (or me) to do the remaining work.

The UK average house consumption (excluding EV and Heat pump) is less than 0.5kW (so 12kWh in 24 hrs) implying @editor, you must be running something high current for quite a long time!

Posted by: @jamespa

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The UK average house consumption (excluding EV and Heat pump) is less than 0.5kW (so 12kWh in 24 hrs) implying @editor, you must be running something high current for quite a long time!

We are, quite literally, power users!

The other question I have is around safety. Are the cheaper, no-name or white-label systems genuinely safe and stable over the long term when it comes to cell chemistry, battery management systems and the risk of thermal runaway?

I’m especially curious about how well these systems handle fault conditions (over-charging, deep discharge, cell imbalance, inverter failure or high/low ambient temperatures) and whether their protection mechanisms and certification regimes are truly comparable to the bigger, more established brands.

Cost and capacity are one thing, but when you’re putting a large amount of stored energy inside or attached to your home, I’m keen to understand where the real risks sit, what standards actually matter and whether paying more is buying genuine safety and robustness or just a logo.

Posted by: @editor

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The other question I have is around safety. Are the cheaper, no-name or white-label systems genuinely safe and stable over the long term when it comes to cell chemistry, battery management systems and the risk of thermal runaway?

...

There is, of course, the question of whether the more expensive branded systems are indeed all those things too.

All, of course, within the context of kit - cheap or expensive - that passes the necessary certifications for domestic installation in the UK.