Home Battery with Solar

Screwdriva

pensionpawn said:

I'm just looking at minimising my import and maximising my export with the minimal amount of cost, effort and stress.

If you have a SolarEdge inverter, you likely have optimizers? If so, the PW3 can be AC coupled till that inverter fails. It will offer whole house backup with a maximum of 7.4kW of Solar PV. 

The PW3 does not support optimization, so you will need to replace the SolarEdge system OR delete the optimizers when the existing inverter fails. 

If it was me, I would delete SolarEdge entirely (unless you have shading) and replace with the PW3 which should cost £7.3K installed. 

pensionpawn

Screwdriva said:

pensionpawn said:

I'm just looking at minimising my import and maximising my export with the minimal amount of cost, effort and stress.

If you have a SolarEdge inverter, you likely have optimizers? If so, the PW3 can be AC coupled till that inverter fails. It will offer whole house backup with a maximum of 7.4kW of Solar PV. 

The PW3 does not support optimization, so you will need to replace the SolarEdge system OR delete the optimizers when the existing inverter fails. 

If it was me, I would delete SolarEdge entirely (unless you have shading) and replace with the PW3 which should cost £7.3K installed. 

Interesting. I have micro-optimisers under each panel working with my 6kW Solaredge inverter, which I wouldn't be looking to remove just to add a certain type of battery. When my inverter fails I will be looking to replace like for like unless there is a compelling reason not to.

One thing I can't get my head around at the moment is, with an 8kW export limit, how is a battery throttled to limit export on sunny days, without limiting power delivery within the house?

Martyn1981

You should be fine. With 7.12kWp of PV split E/W, I assume your sustained peak is ~5.5kW, so less than the 6kW inverter, and less than the 8kW export limit. So even if the batt is full, and house demand is low, you'll still be under the export limit.

If you mean battery export and PV export at the same time, perhaps for export payments, then that'll depend on the output of the battery, but presumably you can set the battery export, so that it monitors total export, and doesn't add enough to raise total export above 8kW?

pensionpawn

Martyn1981 said:

You should be fine. With 7.12kWp of PV split E/W, I assume your sustained peak is ~5.5kW, so less than the 6kW inverter, and less than the 8kW export limit. So even if the batt is full, and house demand is low, you'll still be under the export limit.

If you mean battery export and PV export at the same time, perhaps for export payments, then that'll depend on the output of the battery, but presumably you can set the battery export, so that it monitors total export, and doesn't add enough to raise total export above 8kW?

Yes, my maximum generation is around 5.75 kWs. However, yes, it's the (automated and dynamic?) management of the combined export, compared to the DNO limit, that intrigues me. Hard coding the battery not to export more than a set amount isn't a solution I'd be happy with. This would result in wasted export opportunity during peak time. So what device monitors the instantaneous combined export value and how does that device throttle the battery export to prevent the combined export exceeding 8kWs? So as the solar inverter is exporting 2kWs, 3kWs, 4kWs etc the battery reduces from 6kWs, 5kWs, 4Kws etc.

Basically what I would like to be able to do is tell the system to export at 8kWs (24 kWhrs, or to the remaining charge level) from 16:00 - 19:00 every day.

So many things to consider....

Screwdriva

pensionpawn said:

Interesting. I have micro-optimisers under each panel working with my 6kW Solaredge inverter, which I wouldn't be looking to remove just to add a certain type of battery. When my inverter fails I will be looking to replace like for like unless there is a compelling reason not to.

As expected. Unless you have shading on either aspect, I would remove all SolarEdge components when the inverter goes belly up and use the PW3's built in inverter + DC inputs for the most efficient solution possible. Till that day comes, the PW3 can continue serve as an AC coupled battery in conjunction with your SolarEdge setup. 

badmemory

Are you sure the max export isn't just the max they will pay you for.