Michael Jahrer’s ambitious off-grid solar power plant in Graz, Austria, stands as a testament to the power of meticulous planning and the effective use of cost-efficient components. Developed since 2020 and remaining largely unchanged since October 2022, this system is one of the most robust residential off-grid setups in the region, powering two large properties and supporting sustainable living.
Solar achievement
Michael Jahrer's strategic focus on utilizing cost-effective PowMr components has resulted in a stable and highly efficient power system.
The scale and consistent performance of this system are truly impressive. Since commencing operation in October 2022, the setup has demonstrated exceptional reliability, consistently delivering substantial energy output.
As per the latest statistics, the system has cumulatively delivered 74,606 kWh of AC energy. The year-over-year production highlights the tremendous value of this investment:
- 2023 Production (Self-consumed AC Energy): 21,928 kWh
- 2024 Production (AC Energy Delivered): 30,824 kWh
2023 Performance and Efficiency Metrics
This high level of energy generation enables the system to operate with near-total energy independence.
Based on the 2023 performance alone, it achieved direct economic savings of approximately €6,600 at a rate of €0.30 per kWh while drawing only 137.3 kWh from the public grid, which was used exclusively for battery charging during extremely poor weather conditions.
- 22 solar arrays supplied a total DC input of 26,140.5 kWh to the 48V charge controllers and batteries.
- 60 charge controllers then delivered 25,684.4 kWh of DC power to the inverters.
- 6 inverters produced a total AC output of 21,928.1 kWh to power two houses.
Solar system overview
This massive system is an off-grid, 3-phase configuration built around 86 kWp of photovoltaic capacity and over 100 kWh of LiFePO4 battery storage.
276 solar panels (total 86kwp)
The core energy source consists of 276pcs solar panels, delivering a massive 86 kWp (kilowatt-peak) of power. To maximize power harvesting and simplify current management, the panels are intelligently divided into 22 distinct arrays. The largest of these arrays is sized at 5.7 kWp.
22 solar charge controllers of 60A
The system consists of 22 solar panel arrays, each connected to a dedicated 60A modified PowMr charge controller. This arrangement ensures that each array feeds directly into its own controller, allowing for precise and safe management of the substantial currents.
To manage the substantial currents, all charge controllers, batteries, and inverters are centrally connected to a robust 400mm² busbar, rated to handle a continuous current of 500A, flowing into the inverters and battery bank.
6 inverters connected in parallel for three phase
The 33kw three phase AC power supply is managed by 6 PowMr inverters (POW-HVM5.5K-48V-LIP), which are connected in parallel (two inverters per phase). This modular design allows the system to easily distribute power across all three phases of the electrical supply, such as heating via deep-drilling heat pumps, and charge three electric vehicles.
During the summer months, the system comfortably operates multiple air conditioning units in two houses, as well as a dedicated air-conditioning unit in the plant room to maintain optimal operating temperatures and ensure the longevity of all power system components.
14S LiFePO4 system of 82kwh capacity
The energy storage backbone is a huge 82 kWh lithium battery system built using a 14S LiFePO4 configuration. This setup operates within a functional voltage range of 42V to 47.5V. To safely manage the substantial currents inherent in a system of this size, Michael implemented a crucial "divide-and-conquer" approach across the entire battery and charge controller setup.
