In the past, numerous homes had PV systems installed. Nowadays, home owners are concerned that the photovoltaic (PV) system on their roof may not only have advantages, but could possibly cause health risks, because of the electromagnetic fields caused by the system.
PV systems in operation generate both, static and alternating electric and magnetic fields. The strength of the fields depends on the design of the inverter, the performance of the system and also the way, in which the modules, in series or parallel, are interconnected.
Due to the direct current of electricity in the PV cells, the fields are mainly static fields and therefore less critical for the health. Electrical fields can hardly penetrate into buildings and moreover, can be shielded easily. Magnetic fields on the other hand penetrate building envelopes full force and are very hard to shield. The electric field generated by the PV system can therefore be neglected.
Biologically much more effective than static fields are alternating fields. These arise in PV systems in addition to the static fields by reactions from the network and by superposition of the DC current in the PV-circuit with AC shares rom the grid.
For the lowest possible release of electric smog by a PV system, the inverter should have a transformer to decouple the PV system from grid perturbations (galvanic isolation). Due to higher costs and somewhat lower efficiency, inverters with a transformer are rarely installed.
In case of large systems, the installation of the low voltage grid should be carefully considered. The greater the power of the system, the more energy is being fed into the network. The associated currents can create a remarkable magnetic field. This situation can be solved with the appropriate location of the inverter and/or with the application of a magnetic shield.
In this example a PV system was installed onto the roof of a barn. The inverters were installed next to a wall towards the animals. With a magnetic shielding installed on the wall and on the floor, the magnetic fields were kept away from the animals.
behind and below
|PV panels on roof of a barn|