I am moving from an old Solax SU3700E hybrid contoller which has a built in 2.5Kw charger and 4.2Kw of Solar panels to a Mutiplus 48/5000 GX. I will be retaining the Solax on the grid side of the Mutiplus to service the Solar Panels. I have a very cheap electricity 7p kWh electricity between 23:30 and 5:30 and charge the batteries 5 x Pylontec US300C 90% during this time. I also run an Air Source Heat and do not want the batteries discharging during the cheap electricity period.
So I need to setup the following (same every day)
23:30 to 05:30 charge batteries to 90% (no discharge)
05:30 to 23:30 use PV / Batteries / Grid
I assume that this is an easy setup but don’t have the system to try this out. Can somebody help me out with a programmed example for this.
I understand how to load the ESS Assistant and how the system is installed and configured etc.
Yes, it is easy. You set up one of these, but change the numbers to:
start time 2330, duration 6h, SOC limit 90%,
The rest of the time you need to set your minimum SoC very low (like 10%) to avoid using the grid. But you don’t want to run your batteries flat either.
With ESS during the day, PV goes to loads first, battery second, and export to grid third.
If PV isn’t covering all of the loads, it will draw from battery to make up the difference, until the minimum SoC is reached. Then the grid is used (importing power). There is still some small grid use when big loads switch on and off, and that can annoy some people, but it isn’t really significant.
You can set the maximum amount of power to export to grid, but it is fixed unless you want to change it programmatcially (which is possible).
Once you start getting into optimizing payment calculations, if you are in Europe, Dynamic ESS (DESS) has an algorithm to optimize when you export based on pricing. I’m not familiar with all of the details there, check the documentation.
Pretty easy to do with node red. Here is a flow with a function that checks the SOC is below 90% and the time between 23:30 and 05:30. If its between the hours and SOC is below enable charge otherwise disable the charger. This does not switch of the MPPT just the internal charger.
JSON code is in the text file. I have not seen anyone or myself be successful with the ESS programmed charging it seems to do weird things a never what you want.
I now have a better understanding of what is and isn’t possible. I will start with the simple which is what I have been using for the last 5 years and work my way up from there.
