I always wondered if you could use an Over/under fridge/freezer, cut a hole in the bottom of the freezer through to the fridge, secure the glass and reseal it, and run the lights in the freezer with the freezer on, cooling the light. Plants in the fridge part. If you removed the fridge load on the system(compressor and coil) and routed all the cooling power to the freezer, it might work for a 600 or so...