System Design for Dock Lights
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Hey SunEagle, I was wondering if you could refresh my memory on why you said the following:
"Next to size your panel you need to use 1/10th the battery system Ah rating which would be 20 amps."
What's the math behind the 10% figure? From what I remember you should hope for 4 hours of sunlight a day and therefore multiply the sizing by 4 to get the panel wattage. I feel like I looked up your reasoning when you suggested it but I can't remember it now. I also couldn't figure out how to Direct Message you, hence the zombie post Here.Comment
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Hey SunEagle, I was wondering if you could refresh my memory on why you said the following:
"Next to size your panel you need to use 1/10th the battery system Ah rating which would be 20 amps."
What's the math behind the 10% figure? From what I remember you should hope for 4 hours of sunlight a day and therefore multiply the sizing by 4 to get the panel wattage. I feel like I looked up your reasoning when you suggested it but I can't remember it now. I also couldn't figure out how to Direct Message you, hence the zombie post Here.
Now to make sure you have enough time in the day to replace what you have used in your battery system will depend on where you live and the lowest value insolation hours of the year. So if you use 1000 watt hours in a day your pv system needs to put that back and about 15% more due to losses.
So for example if you need 1000wh a day and you have say 2 hours of use full sunlight then you can calculate the panel wattage. ie. 1000wh / 2hr * 1.15 = 575 watts.
To see if that panel wattage gets you the amount of charging amps then the approximate wattage, which with an MPPT CC, will yield 575w / 12volt ~ 48 amps of charging. That should be able to support a 480Ah 12volt battery system.Comment
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