Lead-acid-battery regulator for solar panel systems

The design of solar panel systems with a (lead-acid) buffer battery is normally such that the battery is charged even when there is not much sunshine. This means, however, that when there is plenty of sunshine, a regulator is needed to prevent the battery from being overcharged. Such controls usually arrange for the superfluous energy to be dissipated in a shunt resistance or simply for the solar panels to be short -circuited. It is, of course, an unsatisfactory situation when the energy derived from a very expensive system can, after all, not be used to the full.