RV SOLAR POWER – THE SHORT COURSE                                    	      by HandyBob 12/08

If you want to solar power your RV & don’t have the ability or inclination to install it yourself, the following is the minimum that you need to know.  Any RV solar dealer that argues with you on any of these points is clueless.  Unfortunately, I believe all of the dealers in Quartzsite will fail this test, even the ones with the “good” reputation.  I have seen their work, repaired a lot of it, and I get mad every time I drive by & see what is going on in their work bays.  Consider buying your equipment on line or mail order & then finding someone handy with wiring to help you install it.  Any good RV tech can do it, but you have to tell them where to put it and the size of wire to use.  I am NOT looking for work, so please find somebody else.  I do recommend Backwoods Solar as a good, honest supplier.  Phone 208-263-4290 - Catalogs are free and have a lot of good basic educational info for the solar power wannabe.  

1.	If you really want to successfully depend on battery power install a Trimetric 2020 battery monitor / recording amp hour meter (sometimes called E meter).  I have hooked up over a dozen of these & everybody loves them.  This is available for less than $200 and should add about $300 installed to the cost of a system.  Installing this before you buy solar & learning how to read it will show you how much power you actually use and help you size your solar system for your needs instead of spending a fortune on panels that some salesman tells you that you need, without knowing a thing about your life.  It will pay for itself.  If the company you are dealing with does not offer this meter or a similar one like the Link or the built-in one that comes in the Blue Sky IPN-PRO remote and tries to tell you that you don’t need it; walk away.

2.	Buy a three stage charge controller that is adjustable and set it as recommended by the battery manufacturer (14.8V if you have wet cell golf cart batteries).  I know of only one RV solar dealer that is doing this.  This controller does not have to be an expensive Blue Sky or Outback unit in order to work.  Both the Morningstar Tristar (my favorite) and the Xantrex C series non boosting “ugly box” units do a better job of charging for less than $200 than any of the little fancy looking flush mounted charge controllers with lights, bells & whistles that the RV solar guys are pushing.  Do not let anybody talk you into anything else.  The expensive Blue Sky Solar Boost 2000E is not a three stage unit and it reduces the power that your solar panels produce before the batteries are full.  A three stage charger keeps charging after reaching the voltage set point.  A $110 Xantrex C-12 (12 amps, only one panel) will do a better job of actually charging a battery until it is full.  Buy an expensive Blue Sky or Outback three stage controller if you have gobs of money, but it is not necessary and not worth the expense on small systems.  If the company you are dealing with tries to tell you that you must buy the small MPPT (boosting) controller or you are wasting the watts your panels produce; walk away.  Seriously, he is in the profit generating business, not the power generating business.

2.	Buy the temperature compensation sensor option ($30).  This will raise the voltage when your batteries are cold, so they will get a better charge & reduce the voltage when they are warm, to protect them from over charging and venting too much electrolyte.  If the company you are talking to does not have the temperature sensors in stock or tries to talk you out of it, they are clueless; walk away.

3.	Insist on the charge controller being located as close to the batteries as possible.  In no case should it be even six feet away.  The voltage drop between it and the batteries will prevent your expensive power from reaching your batteries & getting them fully charged.  Also, insist that the wire between the controller and the batteries be over sized, at least one size larger than required by the amp rating in order to limit the voltage drop to less than 1%.  The wire from the roof to the charge controller needs to be sized for a maximum of 3% voltage drop.  The overall drop, panels to charge controller needs to be close to 5 or 6%.  There are voltage drop tables in the manuals for the good controllers and guess what; they are missing in those for the pretty ones that don’t work.  The voltage drop from the panels to the controller doesn’t hurt if kept to a reasonable level, but from there to the batteries it is critical.  #10 wire is not big.  #4 is the correct size, not overkill, for four panel systems and the dealers in Quartzsite don’t even sell it, which should tell you something.  If the guy trying to sell you a system says that all systems have voltage drop & it doesn’t matter where in the system it is; walk away.

4.	Do not let anybody tell you that it is OK to have any shadows on your panels from antennas, vent covers, air conditioners, etc. no matter how small.  They are setting you up for failure.  Tiny shadows will reduce the power produced by 25 to 50% and covering one square shuts most panels completely off.  Many of the solar guys are clueless about this.  I have proven this time & again to many folks.  This is extremely important!  Again; JUST WALK AWAY!