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Old 09-26-2016, 10:04 AM   #1
Join Date: Mar 2011
Location: Eagle, Idaho
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Solar Panel Wattage

Now that I have decided to buy new batteries, it's time for a solar panel redo. How many watts are enough? My coach has a residential fridge and we do our share of "dry" camping. I also have 6 6 volt house batteries(t-105s). 400 seems like the minimum. I understand that the inverter takes a tremendous amount just to "invert", let alone power things. I would like to do this only once, which is not normally how I do things. Please tell me your experiences and/or ideas.

Pat and Cathy
2005 Alpine 40FDQS
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Old 09-26-2016, 10:48 AM   #2
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There is no definitive answer to this.

You have to weight the cost, complexity and weight on the roof of the additional solar panels and smart controller against additional generator run time.

For many, house battery banks are sized to provide overnight power without supplemental electricity from solar or generator. 400 amp-hrs should do that.

Adding more battery capacity is the same trade-off: cost and weight vs additional generator run time.

Brett Wolfe
2003 Alpine 38FDDS
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Old 09-26-2016, 05:28 PM   #3
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Solar Panel Wattage

Pat, we have a '05 with residential fridge and two 50 watt solar panels (standard from WRV). We have no problems (with a battery bank in new condition) running 2 - 3 days without running the genny. Obviously, if the battery bank has aged or we do not get a full day of sun, this will be less, it also depends upon what else we run during this time.
Dave, Bobbi and Fenway
2005 38' FDTS Alpine Limited, 2016 Jeep Grand Cherokee Limited
Cape Cod, MA
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Old 09-26-2016, 06:00 PM   #4
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How many solar watts do you have now? How long does your battery bank last on average until you reach 50% SOC ?
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Old 09-26-2016, 06:06 PM   #5
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I have 400 watts of solar and 4 8D batteries. How long can I go boondocking?
I don't know yet. Due to the DW's poor health we never got to find out. Now that she died I haven't yet had the time to go anywhere.
I know overnight, then a 600 mile drive then overnight is no problem.
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
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Old 09-26-2016, 06:27 PM   #6
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6, 6 Vdc batteries
1000 watts solar

The ratio of AC to DC is 1 to 10, 1 AC = 10 DC. The inverter uses at least 5 amps.
Do i have to run generator? yes because every few days, the batteries need a good charge. Starting in Bulk mode 80 amps, then 2.5 Hrs in absorption.
Every 12 to 24 hours it will make ice and defrost. That will jump up power consumption to 20 Amps DC by itself.

My system cost me around $2000, this includes the Midnite 150 Classic Controller.
Misc part $200. Made brackets out of angle aluminium.

For those of you bean counters
Generator 3/4 Gal full load. Since my generator does not run with a full load, I use about 1/2 gallons Diesel.
Ok, without solar, I would run the generator in the morning 2 hours. At this time I would use all the heavy electric items. Next run at night, watch TV and anything else. Run for another 2 to 4 Hrs.

Currently, I do not like to elevate panels, so this year I am adding 600 additional watts
Cost less then $1 a watt.

By the way I run 45 Voc panels.
Dale&Susan, 08 Alfa Gold, DaGirlsRv Blog
2015 F-150XLT_1600W Solar_880 AmpHr
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Old 09-26-2016, 07:05 PM   #7
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Depends on what you want to do. Just battery maintaince or never run generator with lots of power usage? I had 600 watts on previous coach. Planning 1200-1600 watts on current coach.
Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.
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Old 09-27-2016, 08:21 AM   #8
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Location: Eagle, Idaho
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paspad1, I currently have only one 50 watt panel (it's what the coach came with). I also am in the process of replacing my house batteries because they are shot. I just returned from 12 days of dry camping in Reno(air races) and the generator got a workout. I'm new to this coach so it's a learning curve but I don't want to go through the whole generator running constantly thing again. Trying to figure out the best battery/solar panel combo for my lifestyle.
Pat and Cathy
2005 Alpine 40FDQS
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Old 09-27-2016, 08:46 AM   #9
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Our rig has 1380 watts of flat mounted roof panels (~ 2 inches off roof) and 660 amps of batteries. In good (as in poor - fair - good - excellent) sun we can sit indefinitely w/o generator if we do not need A/C and reach full charge state by 1 - 2 PM.

Loads include:
- PSW 2800 inverter always on
- RR w/icemaker in steady use
- MW in 3 - 5 minute runs ~ 4 times/day
- Water pump
- Sat TV antenna up - TV on 2 - 3 hours a day
- LED lights as needed
- AH to provide hot water and rare heat
- Phone/computer charge ups every other day

We could do this with less solar wattage - but - when conditions are less than 'good' we still do OK with generator runs of ~ 2 hours a day. Let us know how you proceed and what experience you have - thanks ...

2015 Itasca Ellipse QD | 2014 Jeep Grand Cherokee
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panel, solar, solar panel

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