I am looking to run 2 basic shoplights, each with 2- 32 watt T8 flourecent tubes for 6 hours a day for an indoor garden. Location WI.
Excellent answer from Server Room above. I notice that you mention 45-watt panels, suggesting that maybe you are considering the kind of kit that comes with 3 5-watt panels. I'd recommend against that, as the type of panel that comes in those kits tends to be optimistically rated, and not durable, either. The best way to go for this sort of thing is to use grid power. Then if you want to offset your usage with grid-tied solar, that can be an independent consideration.
I doubt you will be able to get anywhere near the amount of light needed to run anything for 6 hours a day. You will probably need a battery or something as well. At the least, you will need 3 solar panels, but you will probably need more than that in order to charge the batteries to get it to last long enough.
Ok lets start with basics We need 28watts for the lights but due to efficacy we wont get that from the solar panels unless we increase the power.So I would say about 50watts of panels and that depends on if its sunny if its cloudy we wont get even 70 watts so I would say get 200watts of panels to overcome this problem. Then we need to run the lights for 6 hours so we need power to charge the battery I would say we will need 2x 0ah deep cycle battery's and as we need the lights on for 6 hours I would say we will need a charging capacity or total power from our solar panels to be around 300watts. So now that's the power sorted we need a device to allow us to power the lights at the right voltage. You will need a device that is called a inverter if the lights run on 240/0volts you will need a 2v to 240 or 0 depending on were you are so we can now convert are 2v dc power into 0/240 for the t8 lights. You will need a 500watt inverter as when fluorescent lights start they have a surge of power needed to start them So you will need 2x0ah deep cycle battery's 7x 45watt solar panels or you could just get 3x 00watt panels x500watt pure sine wave inverter I know it will be costly but it will be worth it in the long run.I did a similar project myself and it cost me over 600
Lets say, for a simple approximation, that the 45 watt panel produces 45 watts /3 of the time and nothing the rest of the time. Each day, this will produce 8 hours times 45 watts = 360 watt hours. Also assume the battery charge controller and inverter waste half of that power, leaving 80 watt hours per day. If you use compact fluorescent lamps, that would allow you to burn 80 watts worth for an hour every day, or 90 watts for 2 hours, etc. That is a lot of light for a shed. You might consider using much less efficient tungsten filament lamps, but eliminate the inverter and choose low voltage (automotive) lamps that can run directly across the battery and lower the total cost, but give you only about half the light times time. The main advantage of the inverter might be that it would allow you to use small power tools or appliances in the shed. -- Regards, John Popelish
