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How many Solar panels do I need?

Yahoo Message Number: 89762
I have a 200 CC Affinity 42' and LOVE IT! One thing I miss that my old Safari had was solar power. I have been researching what I need and have come across all sorts of formulas etc that all give different answers. I figure I would poll all my Country Coach brethren and see what everyone is running, AND what brands/ good deals you found on them.
Our coach has NO PROPANE. There are 4 house batteries (8D model I think) and 2 starting batteries (also 8D). Does have aquahot, and a household refrigerator. I am interested in enough solar to run fridge, and maybe a tv during the day and night. Any AC we would fire up the generator.
Thanks so much!

Boyd May

2000 CC Affinity 42'
LA (Lower Alabama)

Re: How many Solar panels do I need?

Reply #1 –
Yahoo Message Number: 89767
A general rule of thumb, is figure 1 watt for each Amp Hour of battery power. You have 4 8D's (Not knowing which one, like lead vs AGM, makes a difference on what size AH they may have.), so perhaps a range of from 800-960AH capacity battery bank.
A few other considerations/opinions for you to think thru and answer:

1) Percentage of Boon Docking vs Park power to Park power usage. The more you Boon Dock, the more you will probably want Solar Panels to handle your charging needs.

2) If for occasional Boon Docking, say up to 25%, then I would put in a less substantial Solar Panel system, and augment with the generator.

3) When working with an installer, ask them to 'upward upgrade proof' some of the components. Go with large gage wires then you may need to start with. Go with a larger charge controller then you need, to allow the addition of more Solar Panels if you want to upgrade in the future.

4) Since you are starting from scratch, I suggest you go with a higher voltage 24v or above, set of panels. And though some recommend to shop for the lowest cost per watt on panels. I found in my research that you can see dramatic differences in yield of power output between different solar panels. An area where you 'get what you pay for', as unless you plan to get up on the roof and 'tilt' the panels for optimum power production, you will want good quality.

5) If you decide you want to be as Solar Panel dependent as possible. Then I would add a contingency of 20-25% on the solar panel total wattage. This would allow for partial shade, less then sunny days, and the difference in sun power based upon the time of year, and how far North you may be. (Say you have 800AH of batteries. Instead of 800 watts of Solar Panels, bump that up to 1000 or above, to give you a bit more contingency.)

Work with a professional installer. AM Solar up in the North West gets good reviews (though they seem to have smaller size panels of 150 watts, to target smaller real estate roof space then you have.)Another outfit is Starlight Solar in Yuma (a company that I've started to work with on the upgrade of our Solar Panel system.) Regarding my comment 5, if you future proof some of the components, you can start with say 800 watts, and see how things go. Add more if needed, or just because you want them:)!
If you want to dig a bit deeper, the AM Solar site has very good overall education information. Escapees Jack Mayer also has a good site with good reading info. Send me a PM if you would like some links.
I also know many members on this board have great Solar Panel systems, and they should be able to give you some great input.

Best of luck,
Smitty

04 Allure 31017, 40'

(800ah Lifeline Battery Bank. Going with Panasonic 240S HIT panels (X's 4 = 960 Watts) and Midnight Classic Lite 150 controller.)
04 Allure Sold to a nice new owner! Now enjoying a 07 Magna Rembrandt 45' ISX600 #6775
"We're ONDROAD for THEJRNY!" (Toad and Coach license plates, say Hi if you see us!)
 

Re: How many Solar panels do I need?

Reply #2 –
Yahoo Message Number: 89774
Boyd - Here's my 3 part chronicle on our solar system.
http://www.muniac.com/Power1.html Perhaps one of the biggest systems you'll see on any bus. A quick power balance. At the equator at solar noon (vertical stick wouldn't cast a shadow) the sun produces 1 kW per square meter. Figure solar panels run at a nominal 10% efficiency.
That means 90% of the power doesn't get captured. Also solar panels are less efficient when they are hot. So figure 100 watts per every square meter of solar array area. De-rate for heat, location, trees, shadows and sun angle. As for lead acid batteries, you'll put in 100 watts of charge and get 50 watts back, maybe.

All this said, solar has some merit as a niche electric power source when sun is available. Sadly so much BS abounds with green power agendas, environmentalism and government subsidies. The article I wrote attempts to dis-spell the myths. Design is complex and the best designs will be intelligent compromises and calibrated expectations of what's reasonable given current technology. The goal here is to understand what you're getting and more importantly what you won't get. Solar is very expensive electricity, indeed. I suggest you do some testing with your batteries first. In other words, pull the plug and see what you can run and for how long. Estimate how much power you need to charge them back up. This should give you a ballpark number of what will be required of a solar array. In some situations solar may be best as a supplemental charging source. Not to replace the generator but to reduce its usage. Also our bus is a pig with phantom loads at about 250 watts. The diligent owner can run most of these down and make HUGE improvements. For example, CC installed a solenoid high current switch for the house battery disconnect. The coil sits there and cooks away to keep the connection closed. There are better ways to handle this.
Hidden wall warts in the hi-fi system are other loads. They all add up.
Good luck.

Best - Scott

2006 Allure 430 40' #31349

(Bus-Stead Lemon) My Allure Page http://www.muniac.com/Allure%20Page.html