Voltcraft pl 110sm solar light meter voltcraft pl 110sm p the voltcraft pl 110sm is a robust and easy to operate solar radiation measuring instrument meter to measure the level of solar radiation this allows quick and reliable checking of the efficiency of pv and solar systems p p just measure the solar radiation per m sup2 multiply by the pv system s surface area and then compare to the current grid feed in the pl 110sm is also suitable for determining the ideal location of a new sy