Home PV System
This is my long‑term project. It began when a friend told me that he had received a price quote for a photovoltaic system for his house, but the cost seemed too high. He asked me to research the options and propose an alternative solution. I analyzed the market, studied the available technologies, and suggested that I could build the system for him.
The solar power system is built using three Voltronic Axpert Max King 8 kW inverters, which operate exclusively in off‑grid mode. This means that no energy can be fed back into the public grid. The advantage is that there are no bureaucratic requirements or recurring fees to the distribution company.
The roof is equipped with 27 full‑black solar panels rated at 435 Wp each, resulting in a total installed capacity of 11.745 kWp. The panels are wired into three strings to stay within the maximum MPPT voltage of the inverters. There is also a prepared cable route for an additional string on the garage, which has not been connected yet.
For the battery system, we chose a cost‑effective but riskier option — two 200 Ah LiFePO4 battery packs from AliExpress. I tested the batteries thoroughly, and they turned out to be genuine and met all specified parameters. Later, an additional 300 Ah battery was added to extend the off‑grid runtime without needing power from the public grid.
I assembled and commissioned the entire system. After about three months of operation, it became clear that more detailed monitoring was needed. I researched the options again and decided to use Solar Assistant, running on a Raspberry Pi. All inverters are connected via USB, and the batteries via RS485. This upgrade enabled more precise charge control, better battery protection, and also revealed a weakness of the inexpensive battery packs — weak passive cell balancing. I therefore installed active balancers in the battery packs.
I am currently working on integrating Solar Assistant with the Home Assistant smart ecosystem. This integration enables monitoring of consumption and production, energy production forecasting, and intelligent control of household appliances to maximize the use of solar energy.
