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We recently received an enquiry from someone having trouble with a competitor's solar power kit. So we did a complimentary review of the kit and its components to calculate why the leisure battery wasn't getting enough charge.

The battery in the Caravan was a 12 Volt, 120 Amp hour lead acid battery. To calculate the number of Watts this battery could store/deliver you multiply the Amps by the Volts

12 Volts X 120 Amps hours = 1440 Watt hours

It's not a good idea to completely drain a solar kit battery. More than 70% would be too much so that leaves 70% of 1440 which is approx 1kW hour. Equivalent to a 100 Watt TV on for 10 Hours

100 Watt TV X 10 Hrs = 1000 Watts or 1kW

If you've been running the TV, fridge and lights enough to drain the battery by 70% you need sufficient solar energy to put 1000 Watt hours (or 1kW hour) of power back in the battery. The solar panel in the kit is a 15 Watt panel and was in sunshine for about 6 Hours a day:-

15 Watt panel in sunshine for 6 hours is 6 X 15 = 90 Watt hours

To allow for losses and inefficiencies it's normal to reduce the output of all solar panels by a factor of 0.8 so:-

90 Watt hours X 0.8 factor = 72 Watt hours true production

We need 1000 Watt hours so the competitor's solar panel will take nearly 14 days to charge it. That's ok if you're not using the caravan, but definitely not if you're touring.

1000 Watts required at 72 Watts per day =  1000W / 72W = 13.89 Days

The solar panels we would include in a suitable kit would produce about 480 Watt hours and will therefore recharge the battery in less than 2 days.

  • Competitors kit charges the battery in 14 Days
  • Our kit charges the battery in under 2 days

We design and supply professional solar kits that won't let you down!

If you'd like some more information or help on any of the above please feel free to contact us here.
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