[5] A three-phased PV system

[5] A three-phased PV system

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The PV system, installed on the south facing roof, consists of 24 panels of 160 W each from Shell and covers 30 m2. The cells are made of polycrystalline silicon and have a 25 year guarantee.

Kurt Hellemans: ‘The most delicate parts of the system are the invertors. If their power is too low, they become too hot and will have a shorter life span. If their power is more than necessary, their efficiency goes down. I divided the panels into three sections and installed three invertors to generate three-phased electricity. That was the best option to keep my residential network balanced, since the heat pump compressor is also three-phase. The invertors have an efficiency of 95-98 per cent. I installed them in the attic to be as close to the PV panels as possible, because the DC side of the system has higher losses.’

‘The system reaches its maximum production between eleven o’clock in the morning and three o’clock in the afternoon from April to September. On a nice sunny day, it can yield 22 kWh.’ Generating his own electricity does not mean he is spared from power cuts on the grid. ‘I can not use my photovoltaic system as an Uninterruptible Power Supply’, says Kurt. ‘It simply is not worth the additional cost to provide a UPS function. When the grid goes down, a safety switch cuts my system off and we are in the dark just like our neighbors.’ And what if a power cut happens on a cold winter’s day? ‘Then the heat pump turns off and we have to do without the heating system. But thanks to the excellent insulation of our house, temperature goes down very slowly. In the past six years, we have never had any problems with that.’