WHAT MATH?!?!? Electricity doesn't have any thing to do with it except in very tiny amounts. You need light coverage not heat wattage! There is no math to do! Photosynthesis doesn't work like that. It's a chemical reaction to light wavelengths. I posted numerous papers detailing this. The unit of measure is PPFD Photosynthesis Photon Flux Density, that's the coverage of the number of light wavelengths the plant can absorb. LED's provide plenty of PPFD's, exactly the same as the Sun. So all you need is the correct amount to cover your growing space with a minimum amount.