Technical Support

Please note, I am not a Sunsynk engineer and the advice provided is my understanding of how it should work - use at your own risk.

This quite a complex requirement, so my response is quite long.

I have a similar setup, but I try to not to export my battery power as I am trying to improve my self consumption.

None the less, I did try to see I could get the system to do what you are asking and it does appear to work.

If I understand it correctly, you have a number of PV Grid-tie inverters and between them they are able to produce excess power that is 50% more than you are allow to export during peak PV output and you would like to store this excess power in a battery using a Synsynk inverter and then export some of this stored energy leaving enough to power the loads when there is no PV available (or for a specified time).

Quite often, if the supply authority specifies a limit for export, the grid-tie inverters will use an energy meter to control the grid-tie inverter to reduce the power output so that it will not exceed the export limit. By adding a battery inverter the excess energy can be used to charge the battery and then used for self consumption and/or export any excess to the grid.

Basically this is done by adding an AC coupled battery inverter which can be Sunsynk hybrid inverter. This inverter will use the excess power from the PV Grid-tie inverters to charge the battery.

There are several things to consider for this to work:

1. The battery inverter must be able to be configured to sell power first to the grid.

2. Set the time that you want to discharge the battery. This should be set to a time when there is no excess grid-tie power available, otherwise you not be able to charge the battery properly.

3. Ensure the export limit is set to limit the export of power to the Grid and set it to a value that will meet your expected load and export the excess to the grid. If it is set to high, it will discharge the battery prematurely while you are still expecting it to supply power to the load.

Example: Using 2 * 5kW grid-tie inverters, Solar PV 15kW, 5kW Sunsynk Hybrid inverter (AC coupled) and a battery which will have enough capacity to absorb the excess energy.

Grid-tie Inverters maximum power generation is ~15kW.

Maximum export to the Grid (based on you suggestion that you produce 50% excess power) would be 10kW

Excess PV power would be 5kW that can be absorbed by the battery.

Assuming that the peak PV period is 3 hours, this would suggest that you would need at least a 15kW battery to absorb this excess power.

Assuming your expected load in the evening is 1.5kW and you battery is a 15kWh battery, it would be able to supply the load for 10hrs

Assume that you only need to supply the load for 5hrs, the load requires 7.5kWh and you would be able to export the remaining 7.5kWh to the grid.

To achieve this, set the power output of the inverter to 3.0kW, the inverter will be able to supply 1.5kW to the load and 1.5kW to the grid.

Sunsynk Inverter settings for the above example:

On the screen System Mode>System2

- Untick all the options. This will set the inverter to "Sell First" (This is not mentioned in the doco but is available via Sunsynk Connect)

- Set the value for "Inverter power limiter" to 3000W - This will limiter the inverter to maximum output to 3kW.

On the screen System Mode>System1

- Tick the setting "Use Timer". This will allow the inverter export power to the Grid.

- Set the time that you want to allow the battery to discharge. You can leave the SOC @ 100% as the options Grid and Gen are left unticked. This will specify the period that the system will export power.

- Set the "Power" value to 3000W (or larger). This is the maximum battery-power that can be supplied.

- Do not tick the Grid or Gen option. If you tick the Grid option it will recharge the battery from the Grid.

- Check the settings on the Battery Setup>Shutdown Setting screen are set to the desired discharge %SOC to shutdown the inverter, ie stop the inverter from discharging the battery.