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Old 09-24-2018, 01:07 PM   #1
Join Date: Sep 2017
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Question Cloudy weather and solar

I live on the wet side of Oregon and it is sunny 3 months and rainy/cloudy 9 months. Solar sellers keep telling me panels are better than they use to be but hey, they are trying to sell me something. Anybody in cloudy Oregon or Washington tried solar in the winter? Plan to have small wood burning stove for heat and to dry the humidity out but would love to have energy efficient freezer. Talking about living in year round and lots of boondocking. Plan to insulate the heck out of bus when I get one. Need to charge phone,kindles, couple of lights, and freezer if possible. Have 2 nice Honda generators (2000 +2000i) but would really like solar. Cannot think of any place cloudier in USA besides Oregon and Washington.
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Old 09-24-2018, 02:22 PM   #2
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You just need a lot more of them to get the power you need, compared to someone in Phoenix.

Same for heading farther away from the equator, no matter how sunny, google

Insolation Map
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Old 09-24-2018, 06:29 PM   #3
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It has been a rainy summer here in Virginia. so far it seems I get about 1/5 wattage on cloudy days. Voltage goes up to about 13.6~ 13.9. This is 400 watts of panels. This is not really enough voltage for a good deep charge. I need good sun every 3-4 days to get a good charge on the batteries, then voltage will get to 14.8.

Hopefully others with a lot more experiance with solar will speak up.
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Old 09-25-2018, 06:52 AM   #4
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Solar panels do produce power when cloudy. The amount varies and as others have noted, it won't be a tremendous amount.

Here's a cloudy day post I put together back in 2015 with my last motorhome.

It's likely that you'll need to use your generator in these conditions but solar will still work (depending on conditions) to finish the charge so you don't have to run the generator all day long to get the final 10-15%.

Ditto on solar insolation research - that'll provide the facts.
JD - Full timer out west
Missy - 1998 MCI 102-EL3 - 1.7kW Solar - 10kWh Lithium
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Old 09-25-2018, 10:31 AM   #5
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That answered a lot of questions! I am wondering what it will do to batteries to undergo long term undercharging- we have weeks of cloudy weather, not days.
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Old 09-25-2018, 10:39 AM   #6
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Greatly reduce their longevity. A top-notch bank that can last 10+ years properly cared for can be murdered in a few months if very deep discharging is combined with PSOC abuse

Even with unlimited amps, it might take one hour to get to 85-90% SoC, but amps trails off due to climbing resistance, so to get to 100% Full takes another 6+ hours.

Lead anyway, LFP has no such problem, in fact prefers PSOC cycling, but costs 7x more per AH.

Best solution is an inverter genny, run in the early AM to get to that 85-90% SoC point before solar starts. Then solar to finish the long tail at low amps.

Of course the solar watts must be much greater than any concurrent loads running in order for the bank to get any charge.
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Old 09-25-2018, 10:43 AM   #7
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The goal should be to get to 100% Full at Absorb voltage

as defined by the maker's endAmps spec

before dropping to Float voltage

at least a couple times per week, ideally most cycles.

Need an ammeter to verify and adjust charge source regulators.

An SoC and/or AH counting battery meter can help avoid discharging too deeply.
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