solar

'Heat' and light are really just different parts of the whole electromagnetic spectrum, all of which can, potentially be converted to other forms of energy. There are several common ways of converting the radiation from the sun into energy which we can use and store. One is to use a series of mirrors to heat water to steam which can then be used to drive a turbine which generates electricity. This method uses mainly the infra-red part of the spectrum - the part which we cannot see and which is commonly called 'heat'. A more recent method, now found everywhere from the smallest pocket calculator to huge arrays generating megawatts of power is to use a silicon cell array which is sensitive to light and converts mainly the visible part of the spectrum directly to electricity. The answer to your question is therefore 'both heat and light, depending on the method used'.