Abstract: The invention provides a method and apparatus for measuring and recording the amount of solar energy falling at a place over a given period of time, comprising means for producing a frequency signal representative of the energy falling at the place, the provision of the frequency signal being controlled in response to the level of solar energy falling exceeding a morning threshold and falling below an evening threshold, and the frequency signal being applied to a counter, preferably fitted with print-out means, whereby the counter may record the total energy falling between the morning and evening thresholds.