Adding battery to PV System Help (EDF)

Reed_Richards

mmmmikey said:

Coincidentally I installed an Eastron SDM230 this afternoon as a way of getting solar generation data into Home Assistant - my solar inverters are about 13 years old and there's no convenient way of getting data from them.

Just a point of interest but are you using it to claim FIT payments, and which supplier do you use? My FIT payments use readings from a regular looking Landis and Gyr meter which has a tamper proof seal like a normal supply meter. Given the ease with which you could fiddle the payments with the Eastron I'm surprised it's approved for claiming FIT payments? I didn't notice but does it have a serial number for identification purposes?

The Eastron meter was what came with my solar panel installation in 2019 so yes, that is what I use to submit net generation readings for my FIT payments.  It has a serial number written on the top surface of the meter.  After supplying readings quarterly for over 5 years it ought to be easy to predict what each successive reading should be with only a small margin for error.  So there isn't much scope to fiddle the readings unless I had been doing this from the outset (I have not).  A metal plate covers the rail into which it is mounted so I suppose there could be some sort of seal inside which I cannot see.

My FIT supplier was Bulb so I was force-migrated to Octopus.  I use Eon Next as my electricity supplier as I prefer their EV tariff to the "Go" tariffs from Octopus.

BradWales

mmmmikey said:

ThisIsWeird said:

Hi Jason.

I presume you are on a FIT which pays you for everything generated, but also gives you a fixed rate for export to the grid? Ie, they don't actually measure how much you actually export, but have an 'assumed' %-age, for which they pay you at a much smaller rate than the FIT?

(More recent PV arrangements do actually pay you for everything you actually export, so that would likely be affected by you pinching this for storage.)

So, assuming this is the earlier FIT arrangement, then installing batteries shouldn't affect anything. This is because you are allowed to use every drop of generated electricity in any case, and still get the wee %-age of 'assumed' export.

Hi - my apologies for contradicting you but I don't think it is correct in all cases that batteries shouldn't affect anything. By way of explanation....

If you connect batteries direct to the inverter (called a DC configuration in some places), which is upstream of the generation meter, there is an additional consideration. The issue is that if you charge the batteries from the grid, when you discharge them the energy used will be measured as generation so in effect you would get a FIT payment for charging and discharging the batteries. You either need an approved and certified meter that runs backwards when the batteries are charged (to cancel out the FIT payment from the discharge), or the batteries need to be installed downstream of the meter using their own inverter (an AC configuration). Both configurations are, as far as I know, allowed (or at least they used to be) but you do need to be aware of the metering implications if you connect the batteries to the same inverter as the solar panels.

So it can be done but it may require installation of a different approved meter.

So if I want to connect my solar panels with a FIT should I use a hybrid inverter or an AC converter? The converter appears to be a cheeper option, but I'm not sure it is as efficient. If I do this which tariff, provider should be used to charge the battery? 

pete-20-11

BradWales said:

mmmmikey said:

ThisIsWeird said:

Hi Jason.

I presume you are on a FIT which pays you for everything generated, but also gives you a fixed rate for export to the grid? Ie, they don't actually measure how much you actually export, but have an 'assumed' %-age, for which they pay you at a much smaller rate than the FIT?

(More recent PV arrangements do actually pay you for everything you actually export, so that would likely be affected by you pinching this for storage.)

So, assuming this is the earlier FIT arrangement, then installing batteries shouldn't affect anything. This is because you are allowed to use every drop of generated electricity in any case, and still get the wee %-age of 'assumed' export.

Hi - my apologies for contradicting you but I don't think it is correct in all cases that batteries shouldn't affect anything. By way of explanation....

If you connect batteries direct to the inverter (called a DC configuration in some places), which is upstream of the generation meter, there is an additional consideration. The issue is that if you charge the batteries from the grid, when you discharge them the energy used will be measured as generation so in effect you would get a FIT payment for charging and discharging the batteries. You either need an approved and certified meter that runs backwards when the batteries are charged (to cancel out the FIT payment from the discharge), or the batteries need to be installed downstream of the meter using their own inverter (an AC configuration). Both configurations are, as far as I know, allowed (or at least they used to be) but you do need to be aware of the metering implications if you connect the batteries to the same inverter as the solar panels.

So it can be done but it may require installation of a different approved meter.

So if I want to connect my solar panels with a FIT should I use a hybrid inverter or an AC converter? The converter appears to be a cheeper option, but I'm not sure it is as efficient. If I do this which tariff, provider should be used to charge the battery? 

A standalone AC connected inverter would be best as it would mean no changes to your FIT equipment.