A light would be like 130 watts 2.1 amps 12vdc
This is just a normal light, so I can work in the evening. It is not for the plants. I am sure I can find suitable lighting elsewhere because the greenhouse place only offers this light.
I would like the battery to store power for the lights and maybe something else like a small fan.
I bought a "shed light" from my local Bunnings store (hardware chain store) for $12.50. It has a 15cm square Solar Cell, 3 AA rechargeable batteries and a 10 led light. Ih has a tiny "battery charging" circuit which I suspect just shuts off the solar cells when there is not enough ligth. Runs for about 4 hours on an 8 hour charge. Enough light to work but not enough for my old eyes to read with.
Not sure what I will do with it, either replace the batteries on my weather station or build an insolation meter.
Point is I could hardly buy 3 rechargeable batteries for $12.50! The solar cell is free.
On your fan, remember it will need extra boost to cover the start up current. If you don't already have the circuit for that google "DIY solar air conditioning" you will find a bit of experience there in running fans from solar cells. The most popular fan seems to be a car 12v radiator fan. Pick one up cheap from a wreckers yard.