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Old 03-31-2019, 03:51 AM   #1
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Solar install

Greetings all....I just completed the solar install on our 2015 38RL....I went with one large panel (150 watt)...My primary concern is to have off grid battery charging to keep things in top shape....Those out there thinking of this option....advice I could give you is.....MAKE SURE you don't go cheap on the charge controller.....I have an RV tech background and have installed many solar systems...large and small....some need / want considerable "collection" (many panels) as they use res fridges and large house bat banks.... and drag down there power storage quite fast....We are not power hungry and also have an on-board gen for those times when we need more power and we are not on the grid....
These units (atleast our vintage) have no solar prep (wiring pre installed)....I have found many times the wire size is not adequate anyway from the factory...(bigger is better) as voltage drop from the panel(s) is a real problem....Just inside the door we have the control center.....with gen start...tank status....etc....so I installed the controller in that location....With our 38RL the cabinet just inside the door is mounted on the back wall of the bathroom.(looking forward)...this wall has two plumbing vents in it....So I managed to position the solar panel in the center of the roof....basically above the entrance door....Inside the trailer beside the entrance door I accessed the upper cabinet...Its a shallow-ish cabinet that does not go to the ceiling but inside it is the Back side of the Bathroom wall.....I used a razor knife and cut a 10" square hole thru the panelling and the two plumbing vents were directly behind it...drilled a hole thru the vent shroud on the roof and fed the solar wires beside this vent pipe into the top of the cabinet where I had the paneling cut out.....After that it was a short trip to the controller which is located on the side of this cabinet..(beside the steps going forward)...
Remember to feed the + solar wire to a on/off switch first before you go to the controller....heavy enough switch to easily take the full rated "DC" power of the panel....(careful.... AC rated switches need to have a considerable higher rating to deal with DC)....This Bathroom Wall is hollow and has many wires traveling down to the basement....so fishing the wires down then across heading forward to the battery compartment is not hard but does take some patience....again use heavy wire (I used #8....but #6 would have been better).....attachment to the battery bank is straight forward.....Please don't forget to put a fuse in the + line going to the batteries.....(double the rating of the panel(s)...I used a 20 amp fuse....This is for fire protection....In case there is a short somewhere/sometime the fuse blows before the full load of your battery bank starts a fire(locate this fuse close to the battery bank )....I have a large boat also and nothing in regards to wiring moves around a boat with out a fuse ! Tough specs that I wish the RV industry would adopt....but they are getting there...
Solar controllers....I have used many different types / brands....dont get sucked into no name brand ...cheap stuff found on ebay....from off shore....My (3) personal installs I have 30 amp Samlex controllers...I really like these units....you can change battery profiles(for different battery types....they have a (4) stage battery charging routine and many custom charging profiles can be entered by the user...plus they have a LCD screen that provides any data you need to keep an eye on things.....all "musts" for me....but there are many good controllers out there....advice....don't go cheap....find something from a solar company that is feature rich....Don't under rate your controller...so more panels can be added if you feel the need....Our boat has 400 watts....enough that in the summer on the west coast I start our genset rarely when we are on the "Hook"..
Take care all...Safe Travels....
Wes
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Old 04-06-2019, 10:24 PM   #2
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More Considerations

The available solar components haven't changed that much over the years..... but thankfully things have come down in price....With China being by far the biggest producer of panels (all types)....prices have really gone down on this expensive item....as with anything...."start - up " production of solar panels had growing pains....poor quality...toe to toe with non offshore made panels they produced less power....and degraded far faster (yes panels do degrade and go down in output over the years)...However....for the last few years China made panels have had a good run...no real issues....efficient as any....and a great price...Solar was once regarded as a fool hardy addition to an RV because of its total cost recovery..Now having solar system on an RV makes sense....whether you are a boondocker or site to site traveler...(maybe not that important to a full timer...parked in a full time RV lot....plugged into the grid)..
The two controller "types" most commonly available today are PWM and MPPT units...Both have their pros and cons..
The PWM type controller (Pulse Width Modulation) is the "chevy" of these controllers....basic in how it performs....does not charge your batteries as fast...not as efficient....but very reliable....cost less....and usually is smaller in size (lack of any real "heat sink" attached)....Its also old tech in regards to controllers and is slowly being replaced ...
The MPPT type controller ( Max Power Point Tracking) is the high end "Caddy" in regards to its charging ability....uses a processor and algorithms to track output power....really do get the job done better and faster than its low tech cousin...However there is a cost for everything....These units can cost 2-3 times more than a PWM unit....have a higher failure rate (thermal stress )...usually have a bigger footprint....While failure rate data is true....a quality MPPT controller is very reliable as internal components have improved and larger heatsinks to control temps....
One more thing that is a very common question is : One controller with two battery banks ? A common scenario for many of us that also have an on board genset that has its own battery...up until recently this was not an easy problem to solve with out adding another controller to the system to deal with the second battery bank....Running one solar system into a splitter / combiner is a poor option....with the diode pack in the splitter stealing considerable voltage in its operation (nature of diodes)...resulting in lower voltages reaching the batteries which can cause premature battery failure thru sulfation....The good news is....some of the solar component manufacturers are listening...."GO POWER" for example has some of their controllers with two outputs....so they can deal with two battery banks....solves this issue (somewhat)....they are a "priority" type set-up.....your house bank should be plugged into the #1 output terminals and the lesser used bank (gent set) is attached to the #2 output terminals...The secondary bank will receive no charging until the #1 bank is charged....What it is , is a "voltage sensing relay" (solid state) built into the controller...so not the magic we were hoping for.....but it does work...We have had VSR relays in the marine industry for years and they are reliable...however they are often in a high charge rate application (lots of amps coming from a high output alternator)..
Another way to charge two banks is to simply install a battery switch that has two outputs and one input....that way you can manually take care of things if needed to divert charging to another source...
Wes
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