Calling Solar Gurus
It's time to pull the trigger and install solar on our 1181. I'm planning to order within the next month to be ready for a trip near the end of summer. The TC is pre wired for solar. I've decided to w...
Forum Discussion
I agree HandyBob is a lot of rant and mostly dated advise that is not consistent with current, state-of-the-art equipment that is available.
WANNABEGONE
Don't overthink this whole thing too much. I'd go with your current equipment selection - wire in parallel (more on you wiring below) and enjoy your solar. That's a good, sound setup that should yield between 800 - 1000 watts per solar day. Manage your loads accordingly.
If your existing wiring is 10ga. you'll see a 1.59% voltage drop over 12 feet and if it's 12ga. you'll see a 2.53% voltage drop over 12 feet. While it's always best to shoot for the lowest possible drop - these are within the accepted "Maximum 3% overall for a feeder circuit" common in solar systems. Trying to squeeze out another 1% voltage drop will yield you an extra 8-10 watts (0.8 amps) per day. I'm sure you can find plenty more than that in wasted loads.
The best thing you can do for the optimum (off-grid) solar design is to design a well balanced system. Balance between charge capability and battery storage size. Most folks are "over-batteried" for the amount of panel. If you have (2) Trojan T-105 6V batteries you'd want to design a system with about 280watts of panel in order to fully replenish the batteries after 50% depth of discharge. (Keep in mind that at 50% DoD is usually first thing in the morning when there is little or no sun and you need some power). Still, you'll need a generator or some A/C (assuming you have a good triple voltage converter) to perform a regular equalize as you don't have enough real estate to put that many panels up on the camper.
If you feel you need to have the optimum system for the least cost (assuming about 225Amp (20 hour) battery capacity) then I'd go with a single 300Watt (high voltage) panel into an appropriate MPPT controller (that can handle 36-44Voc panels) with your existing wiring. Otherwise - just buy what you intended and wire in parallel.
Dan (the OTHER Solar guy)
WANNABEGONE
Don't overthink this whole thing too much. I'd go with your current equipment selection - wire in parallel (more on you wiring below) and enjoy your solar. That's a good, sound setup that should yield between 800 - 1000 watts per solar day. Manage your loads accordingly.
If your existing wiring is 10ga. you'll see a 1.59% voltage drop over 12 feet and if it's 12ga. you'll see a 2.53% voltage drop over 12 feet. While it's always best to shoot for the lowest possible drop - these are within the accepted "Maximum 3% overall for a feeder circuit" common in solar systems. Trying to squeeze out another 1% voltage drop will yield you an extra 8-10 watts (0.8 amps) per day. I'm sure you can find plenty more than that in wasted loads.
The best thing you can do for the optimum (off-grid) solar design is to design a well balanced system. Balance between charge capability and battery storage size. Most folks are "over-batteried" for the amount of panel. If you have (2) Trojan T-105 6V batteries you'd want to design a system with about 280watts of panel in order to fully replenish the batteries after 50% depth of discharge. (Keep in mind that at 50% DoD is usually first thing in the morning when there is little or no sun and you need some power). Still, you'll need a generator or some A/C (assuming you have a good triple voltage converter) to perform a regular equalize as you don't have enough real estate to put that many panels up on the camper.
If you feel you need to have the optimum system for the least cost (assuming about 225Amp (20 hour) battery capacity) then I'd go with a single 300Watt (high voltage) panel into an appropriate MPPT controller (that can handle 36-44Voc panels) with your existing wiring. Otherwise - just buy what you intended and wire in parallel.
Dan (the OTHER Solar guy)
