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How to Monitor and Manage MPP Solar Inverter

How to Monitor and Manage MPP Solar (Voltronic Axpert) Hybrid Inverter/Solar Battery Charger with Enapter EMS Toolkit and ESP32.

Few time ago I decided to put some efforts for building my small solar power plant. The main purposes were to learn little bit more about solar technologies and as a result to get a setup which can handle following use-cases:

To power outdoor lighting from batteries during the night and charge battery from solar during daytime;
To use an outdoor power outlet to charge my Ryobi One+ tools;
Backup power in case of rare outages.
The calculation was rather simple because outdoor lighting was build using LED lights with total required power of 110W. The average lighting time is 8 hours, so I need 0, 9 kWh storage system. My Ryobi One+ battery charger is 55W and if I would like to connect two of them, I need around 110W during daytime + reserve to charge the batteries.Before I started to choose equipment, I needed to take into account following points:

The system should be compact as I wanted to use outdoor enclosure rather than put it inside my house;
There is a period during the year when there is not enough sun. Therefore I need batteries which can be charged from the grid as an option;
The equipment should stay fine when it’s below 0°C temperatures.
The first challenge was to find the right place to put my solar pannels on. The trial was done on the ground with 60° angle as recommended for my region but it was not conviniet, so i’ve decided to go with mounting pannels on the fence around my land - luckily we have side which looking directly to the south.

The next step was to mount inverter and batteries. It was also rather long story with a lot of cabling and boring visits to the shops :)

I decided to go with hybrid inverter which combines solar charge controller, battery inverter and grid inverter. So in general it is like UPS with additonal solar input. The advantage is compact size and possiblity to select energy source for battery charge and output to the load.

You can find many of such inverters on the market under different names. What is unites all of them is similar communication protocol with PC which is called “Watchpower”.”

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