Help choosing power supply

Widget
Widget Registered Users Posts: 1
in Off Grid Solar & Battery Systems #1
Hi I just joined here. I am after a little advice please. I need to run some lights and have no mains power. It is for horse stables. If I were on the mains I would need to run 5 light bulbs and would probably be ok with the light you get from a standard 60w bulb. I am on a budget! I thought maybe a 12v battery with an inverter and then 5 low energy bulbs. Would that work? What size inverter do I need? Do I use normal mains wiring?

I'm sure these are silly questions but I know nothing about the subject and am a non DIY proficient woman! I just need to see to care for the horses after dark. Power for a kettle and radio and a few more lights would be good but I can do without it so if it adds a lot to the cost I would do without and just have the 5 lights.

Thanks in advance for any advice.
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  • Photowhit
    Photowhit Solar Expert Posts: 6,006 ✭✭✭✭✭
    #2
    Re: Help choosing power supply

    To decide what your needs are and if solar can provide them most cost effectivly we need to know a bit more.

    What your power needs are, you say 5 lights, how long will they be on each day? Kettle as in a water heater? (solar doesn't heat and cool very easily)

    How close is grid power?

    Do you have unshaded southern exposure at the stables?
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
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  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    #3
    Re: Help choosing power supply

    Welcome to the forum.

    The first thing you need to do is determine how long you'll need those lights on for: the amount of energy you need to store is measured in Watt hours.
    A 60W incandescent can be replaced by a 13W CFL. One 13 Watt CFL run for 1 hour is 13 Watt hours. Five of them would be 65 Watt hours. As you can see, that's just a little bit more than what one 60W incandescent would use in the same time.

    The inverter just for these lights would not need to be very large as the total Watts here would only be 65. The big issue is how long you leave them on, because that determines the battery size. Roughly speaking you'd need about 12 Amp hours (minimum) of 12 Volt battery for every hour you run the lights. Adding a radio to the loads would not take much more power.

    Now if you throw an electric kettle into the mix you go completely off the deep end. They tend to consume on the order of 1500 Watts, meaning right away you'd need a much larger and more expensive inverter. Plus you'd need more battery power to back it up, even if you only boiled one pot a day.

    All that does not address the issue of recharging those batteries. Even small amounts of solar panel costs money. How far from utility power is it? If it's out in a field somewhere miles from standard electric it might be worth it. Otherwise it probably isn't.

    As with so many things the devil is in the details.
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