The capacity of this largest solar power plant in Finland is over 340 kW. The plant produces about 275 megawatt-hours of solar power each year, which corresponds to the electricity consumption of about 137 one-bedroom apartments. The solar power system was procured as a cooperative effort of VR Group's property unit and its subsidiary VR FleetCare that maintains the rolling stock. In summer a 420-kilowatt in Oulu facility will topple Helsinki from the throne, but another plant due to begin operations during the autumn will return the title to. Mar 17, The performance of solar generators is measured in kilowatts (kW), with variations depending on the design and intended application. Helen's plant will increase the. Its full capacity will be approximately 330 kWp (the maximum capacity produced by the panels under standard circumstances). To maximise efficiency in Finland's northern conditions, the panels must be carefully set up in the optimal direction.