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Battery Storage Update - 2 years in


MikeGrahamT21

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Where on earth has that 2 years vanished?

 

So coming up on the 2 year installation of the inverter and single module battery, and as with most things these days, the gradual improvements to firmware over time have made a huge difference.

 

So at the last update I'd managed to get the power leakage down through an offset, and the whole system was a lot more accurate, but nonetheless still had a small amount of leakage throughout the day which was averaging around 0.5-0.6kWh, certainly not insignificant.

 

image.png.2f87f476c714f8c1fde70b7bb9ccf6d4.png

 

It turns out that not long after i bought this setup, Solis released a Version 2 of the inverter, which came with an external RS485 Meter, to connect the CT clamp to, and i believe this was done to improve accuracy, gutted i missed out on it, and theres no way of adding it without swapping the inverter, so thats a definite non-starter. I got back in touch with them to see if there was anything more they could do, and it was decided that I would move away from the firmware which supported the fixed offset (A1 branch), to the generally available firmware and ended up on version 17014, which was clearly much improved as now the leakage looks like this...

 

image.png.35a22abc44870ef3d732e2ee5c321ffb.png

 

At the end of september I decided to move over to Octopus Flux to take advantage of the cheaper rate during the night to charge the battery up.

 

To compare both scenarios i have taken the same December - January Period (clearly at this time of year, solar input will be minimal), last year and then this year.

 

Neither of these include any standing charge, this is purely for energy alone.

2022

Electricity 8th Dec. 2022 - 31st Dec. 2022 - Total amount after reimbursement from goverment £44.45
Energy Used 141.3 kWh @ 48.45p/kWh £68.47
Energy Price Guarantee 141.3 kWh @ 17.00p/kWh -£24.02

 

2023

Electricity 8th Dec. 2023 - 31st Dec. 2023

Energy Imported
15.15p/kWh 130.2 kWh £19.731
25.26p/kWh 17.8 kWh £4.491
35.36p/kWh 3.4 kWh £1.188
Total consumption 151.3kWh @ 16.79p/kWh (Average unit rate)  £25.41

 

So taking into account the government reimbursement from last year, the energy pricing on standard variable tariff this year is around 4p cheaper than the same period last year. I've not included the amounts for export, as they are minimal at this time of year also. Otherwise the battery has saved me almost £20 in that single month, by being able to use cheaper electricity, and in effect shift my load.

 

Maybe another month, or thereabouts and I should be able to stop charging from the grid again until autumn, and rely wholly on the excess Solar PV to run the property. The better months of the year for Solar should be really interesting, as at the peak i'll likely be able to totally drain the battery, and still charge it up enough after peak export period to keep me til the next morning, should be able to accrue a good amount of credit from export. I shall report back in the autumn!

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That leakage has improved even further since, why I’m not quite sure as the firmware is still the same, but my power curve now looks like this on a daily basis:

 

image.png.02f71f538c6902a1b3f7648dc7a6b367.png
 

Having not needed to charge from the grid so far this month, from 1st to 12th I’ve only imported 1.38kWh, and the majority of that will have been small spikes over the max output of the inverter, which are few and far between but can happen on a real dark day which we’ve had quite a few of lately.

 

Estimated cost is £0.33 for import so far this month (exc standing charges) and I’ve been paid almost £10 for my export to the grid.

 

Gas usage is slightly elevated this year due to the old bathroom being ripped out and rather cold air coming up from under the floor, which stands around £6 exc standing charges, so I’m in a small profit so far this April 

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