@transparent Eleven Energy have a full Sodium-ion system with inverter, no recommendations

Posted by: @scalextrix

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I'm hopeful that the newer Sodium Ion chemistry launched by BYD for their small affordable domestic car market may soon find it's way into stationery battery storage.

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16 sodium atoms walked into a bar, followed closely by a masked man in a cape.

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Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Na Batman!

Sorry; couldn't resist. Taxi's already on its way.

@majordennisbloodnok I’m not sure you will be able to receive treatment on the NHS!

Posted by: @transparent

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The concepts behind running inverter, BMS and battery combinations are just as important as the 'rules'.
You gradually get a feel for the subject matter.

That gut-feel is crucial in the learning curve to making decisions which are 'safe'.

Hats off to the ones that persist, @Transparent ! 😀

Not saying never again, tempting to think learnt enough and the next battery DIY assembly would be quick..😉

But those pleasant moments packing the cells into the box will not be easily decoupled from the weeks leading up to it... 😃

@jamespa I have 5kW PV and 5kW battery. By using the 8pus cheap rate and PV to charge the battery, for the months April thru October I averaged 98% on the cheap tariff, the battery was supporting the house after PV declined avoiding paying higher rates standard hours.

Now the temps have dropped below 8C, the HP is working harder and the battery is not big enough to support the house load.

I calculated adding a second 5kW battery would support the HP at 1.6kW max load Nov-Mch. The payback for this extra battery would be twice that of the first battery as it only pays back Nov-Mch, approximately 18 years assuming static electricity charges, 14 years if you assume 2.5% increase per year.

If I can get a second hand battery at half the cost of new and avoid fitting charges by installing it myself, I could justify a second battery. 

Posted by: @agentgeorge

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@jamespa I have 5kW PV and 5kW battery. By using the 8pus cheap rate and PV to charge the battery, for the months April thru October I averaged 98% on the cheap tariff, the battery was supporting the house after PV declined avoiding paying higher rates standard hours.

Now the temps have dropped below 8C, the HP is working harder and the battery is not big enough to support the house load.

I calculated adding a second 5kW battery would support the HP at 1.6kW max load Nov-Mch. The payback for this extra battery would be twice that of the first battery as it only pays back Nov-Mch, approximately 18 years assuming static electricity charges, 14 years if you assume 2.5% increase per year.

If I can get a second hand battery at half the cost of new and avoid fitting charges by installing it myself, I could justify a second battery. 

Personally, each extra 16kWh costing £1000, when adding battery capacity to the inverter, I am looking to minimise space near the inverter.  

On ROI, by exporting mostly at peak times, return from future PV production can also be improved.  

Posted by: @agentgeorge

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Now the temps have dropped below 8C, the HP is working harder and the battery is not big enough to support the house load.

I calculated adding a second 5kW battery would support the HP at 1.6kW max load Nov-Mch.

That comment is welcome, but can be read in two different ways.

Since others will be reading here in future, I'd like to add some clarity.

If you need more power into the home from your battery storage system, then you add another inverter.
That allows more watts to be delivered.

If you want more stored energy, then you add another battery.
That allows you to supply the home for a longer period of time. 

You might need to do both, because these two concepts interact.

Adding a second inverter will drain the battery faster, potentially leaving you without enough stored energy to last through the night.