Solar / Battery Storage considerations

Yes, the card will work for Agile Outgoing too, I’ve just tested it, see below, albeit we’re on fixed but it’s getting each period successfully

When you setup teh card you have to include the entity. Just change to the export entity, i.e.


Change the XXXX’s to your own Octopus values.

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No reason why anyone should be interested but the scaffolding is now all up. Install next week!


Thanks. I’ve been too busy with gardening to play with HA. Where is the Octopus tariff integration?

Flux is the best tariff for me export wise. I won’t be importing until October and then at the cheap rate.


The Octopus integration is available from within HACS ( Home Assistant Community Store). If you don’t have HACS you’ll need to get that first and then you can get the integration add-in…

The rate card is also in HACS and is called octopus-energy-rates-card.

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What spec is it?


Total 8.2kW, with 4.6 to the rear and 3.6 to the front. Rear is east north east facing with much larger roof area available and front is west south west

I think the batteries are around 14kWh. The inverter is going to be a single 8.2kW unit. I think we are having an Eddi to use surplus generation for hot water

Here is a view of the rear

The house is not detached and the split is not symmetrical - at the rear we have more width at ground floor / rear (35 feet) and much less in the loft / front (20 feet)

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Some statistics for May verified by Smartmeter
and the Net meter for the inverter. The panel production is from SolarEdge.

Panels 842.27 kWhp
Grid Import 188.77 kWh (168.2 to Batteries, 20.57 to house while batteries charging)
Grid Export 484.52 kWh
Inverter Out 912.25 kWh
Inverter In 168.2

Self Consumption = 912.26 - 484.52 + 20.57 = 448.31kWh of which
EV charger 62.2kWh
ASHP 92.9 kWh

Inverter Efficiency = 912.25 / (842.27 + 168.2) = 90.28%

I don’t entirely trust the figures from the SolarEdge App.

@TimOopNorth I would advise having an Import/Export (Net) meter as you are having battery as the extra cost now is minimal. Better still one with a digital interface for reading either via Modbus or Mbus.


All a bit frustrating - installer hasn’t commissioned the panels etc which were all installed yesterday. Pleased they managed to fit 10 on the front (and 10 rear) as front is a bit more south facing. They held off as they persuaded themselves that we are imminently getting the supply split but there is no date set for that and brother in law is dragging his feet a bit to avoid having to pay a full standing charge (rather than one third).

I am not sure what say we will have in smart meter being installed - will worry about that nearer the time

Anyway, being commissioned a week tomorrow

It takes time to issue the MCS certificate and get the DNO approval letter. I’d certainly recommend Octopus Flux tariff. Octopus are fussy about meters so you might need another if it is fitted by another supplier.

As my figures show we hardly use much at this time of year. I have been waiting for some sun the last two days to charge the car which needs 54kWh. Meanwhile we export 11kWh/ day at 36p/kWh.


I will certainly be signing up with octopus when we get the supply split. My only problem might be the export of wind turbine surplus as we have deemed 50% export on that. Might be worth losing for a better price but then that overlaps with the neighbours’ share of fit including export so unsure what the practicalities will be. The others won’t want overnight tariff differences I don’t think

Hope you are making progress getting your DNO to split your supply. I suppose you are benefiting from the solar already.

I’m gradually managing to eliminate the solar wastage from having a 3.68kW export limit by using the Zappi in ECO mode from 8 am - it exports at 1.3kW while the battery is charging before dumping all the solar. It’s only from noon till 3pm when the solar exceeds the export limit. We don’t do a high mileage at the moment so it just a matter of spreading the EV charging out as much as possible. At least I’m not dumping into the hot water cylinder when the heat pump can do that more efficiently (2kWh every two or threes days is enough).

The SolarEdge inverter is sneaky by reducing the Solar reporting to the amount it can process when the battery is full.

I do feel that with better design I wouldn’t have these problems. SolarEdge are in the process of releasing a new App that allows the owner to update the battery import and export. All I really need is a button to tell it to export at the maximum rate when there is enough on the battery. There is no AI or even intelligence in their software!


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Good news, the hot water wasn’t connected properly to the solar meter, so the solar app wasn’t reading the hot water consumption. So we have that fixed and the solar and main meters pretty much match each other now. No refunds though, as the power companies meter was the correct one.

Our solar generation has tanked getting close to the shortest day, nudging 20 to 25 KWH on a good day.


Frustratingly the solar installers didn’t commission it last week - coming back tomorrow. For some reason they got it in their head that the split was imminent so they were going to wait for that. I think the MD is doing too many things at once…. And no idea when the split will happen. Difficult to get a straight answers from my bro in law

Should know more after the weekend with a couple of days post commission experience

But, got someone to check out and service the ASHP yesterday (found someone local who seemed very competent and knowledgeable so pleased with that). Discovered that the installers hadn’t set up the weather compensation :person_shrugging:. So that all seems like a good step forward

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I wish ours might or at least proportionally at 6.3kWp. But we are 52 North!

It very frustrating that that installers don’t do enough checks. Good that it is resolved.


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ASHP WC is a matter of trial and error. It can be a can of worms! Much depends on whether the system has been properly designed. If you have a good monitoring system with heat and electric power & energy meters displaying minute by minute data you should be aware of how well your system is performing. Short cycling is a big issue.


Is this to show the correct export? How close now?


Yesterday the solar app shows 31.1 imported and 6.0 exported (20.2 generated). The power company meter shows 31.7 and 6.6 respectively, so pretty close. Actually, both show a net import of 25.1.

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That’s about as close as I get. I also have an Emporia Vue 2 energy monitor on 16 circuits which seems to show about 0.6kW difference.

The worse error is between the import:export meter on the inverter and the SolarEdge App house consumption. I concluded that their consumption is based on the difference between the inverter, the import and the export. So now I use the reliable energy meters.

I need confidence in the various figures to be able to calculate the return on investment for the EV, ASHP and Solar+Batteries.


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I’m interested to know how long it takes to fill a battery. In the south uk and hot weather a high sun. Also can battery be filled by cheap Octopus tarrifs of 3/4 hours overnight. Appreciate lot of variables of course!

It depends on whether you have AC or DC coupled batteries. If AC then the battery inverter controls the rate of charging up to it limit. Both depend on the panel production, but DC is not limited by the inverter.

Charging off the grid is determined by the inverter power.