I have a Sunsynk 3.6 Ecco with rack mount batts. 

I have it set to charge from the grid 0030-0430 when off-peak, but I would like to top the battery up later in the day with exported solar if its available to top up ahead of the evening. My solar is on another grid-tied inverter, not through the Sunsynk. The Sunsynk CT is on the grid and correctly reads import/export.

My solar is very unpredictable, so if I set the system mode to say 80% for a timeframe and the battery is below this then it will charge using the grid export only, without importing from the grid, as I'd like. But if there's no or insufficient solar and I'd like to support the house loads, it will of course only do this down to 80%. This doesn't really help and I may as well just leave the battery to drain, but it seems a shame to export to then import expensive electricity later in the evening when the batt could have charged.

I have the battery set up in HA and so could find an automation to tinker with the battery %s based on current grid, but this seems quite overcomplicated.

I understand if the Sunsynk has the strings it will charge the battery using excess solar regardless of the battery SoC set in system mode. Is there a way to replicate this with a separate grid-tied solar inverter?

1 hour ago, terribleocotopus said:

I have a Sunsynk 3.6 Ecco with rack mount batts. 

I have it set to charge from the grid 0030-0430 when off-peak, but I would like to top the battery up later in the day with exported solar if its available to top up ahead of the evening. My solar is on another grid-tied inverter, not through the Sunsynk. The Sunsynk CT is on the grid and correctly reads import/export.

My solar is very unpredictable, so if I set the system mode to say 80% for a timeframe and the battery is below this then it will charge using the grid export only, without importing from the grid, as I'd like. But if there's no or insufficient solar and I'd like to support the house loads, it will of course only do this down to 80%. This doesn't really help and I may as well just leave the battery to drain, but it seems a shame to export to then import expensive electricity later in the evening when the batt could have charged.

I have the battery set up in HA and so could find an automation to tinker with the battery %s based on current grid, but this seems quite overcomplicated.

I understand if the Sunsynk has the strings it will charge the battery using excess solar regardless of the battery SoC set in system mode. Is there a way to replicate this with a separate grid-tied solar inverter?

Without knowing all your details I would start by making sure you use all your PV for own use before exporting via the 2nd grid tied inverter. Without knowing your area or size and number of panels as well as kwh of daily self use power it remains a shot in the dark. 

One would like to have a complete picture. Yes knowing the whole system one can perhaps start with keeping the minimum panels on the grid tied for operation and moving some to the Sunsynk. This can get you to reduce or not use grid to charge the battery during the night. One can perhaps with low PV for charging use the grid to top up latish in the afternoon to discharge during the whole night and recharge after sunrise. 

I would rather run from the grid to preserve battery power than charging in the early morning slot. 

I would also emmploy a good time of day sunshine APP instead of the typical PV forecast APPS. 

Edited February 18, 20242 yr by Scorp007

On 2024/02/18 at 11:12 AM, Scorp007 said:

Without knowing all your details I would start by making sure you use all your PV for own use before exporting via the 2nd grid tied inverter. Without knowing your area or size and number of panels as well as kwh of daily self use power it remains a shot in the dark. 

One would like to have a complete picture. Yes knowing the whole system one can perhaps start with keeping the minimum panels on the grid tied for operation and moving some to the Sunsynk. This can get you to reduce or not use grid to charge the battery during the night. One can perhaps with low PV for charging use the grid to top up latish in the afternoon to discharge during the whole night and recharge after sunrise. 

I would rather run from the grid to preserve battery power than charging in the early morning slot. 

I would also emmploy a good time of day sunshine APP instead of the typical PV forecast APPS. 

Hey - thanks.

It's a 5.2kw array, split into a south-string with 7 panels and a west-string with 6 panels. The grid tied is a Growatt MIN 4600TL XE. Start voltage on that is 100V.

I get paid more for export (15p) in the day than I do for import overnight (8p), so topping the battery up with excess solar is really to avoid heavier use evenings where I may end up importing on the on-peak rate (29p), saving some money even with the opportunity cost of lost export. Because of the export rate, I would lose money using only solar to charge the battery instead of making the most of charging off-peak, and using grid to top up the battery late in the afternoon I'd really like to avoid as that cycles the battery without really saving me anything, as I could just use that import later in the evening directly if no battery available.

Noted re: sunshine vs PV forecast, I'll check that out! Thanks. If I end up automating SoC % via Home Assistant I'll play with that.

 

Edited February 19, 20242 yr by terribleocotopus
correct off-peak