Which Solar Panel kit to buy?

[Dan Grec]

Does anyone have a link that explains why exactly I need a charge controller in such a small 'RV' setup?

I understand the idea completely (from a friend's setup at his cabin), but I've seen RV and 4x4 setups that don't bother with a charge controller, they just have the solar panel wired directly to the battery. Obviously this will shorten the life of the battery... anything else?

I'm also wondering if charge controllers allow for the aux battery to be charged from the alternator when the engine is running?

Thanks,
-Dan

 

[pods8]

Not sure if I like the automatic EQ though. I'll have to look at a manual and see what's actually going on there.

It has two settings, flooded and sealed. Only the flooded EQs. The sealed does not, has a slightly lower bulk charge at 14.1V though. I plan to run it sealed for my AGMs.

Does anyone have a link that explains why exactly I need a charge controller in such a small 'RV' setup?

I understand the idea completely (from a friend's setup at his cabin), but I've seen RV and 4x4 setups that don't bother with a charge controller, they just have the solar panel wired directly to the battery. Obviously this will shorten the life of the battery... anything else?

I'm also wondering if charge controllers allow for the aux battery to be charged from the alternator when the engine is running?

Thanks,
-Dan

Because a solar panel at full power can be putting out 17-18V+, a tiny panel (IE those little 5-10watt deals) the battery would likely be fine but that isn't going to do well (edit: with a large panel). I suspect it'd likely over charge and cause an AGM to outgass, don't know for a fact just suspect it, and if that happens your battery life/capacity will be drastically reduced.

You charge controller has nothing to do with the alternator, they're completely independent and no you can't use one to condition altenator voltage. You need a DC-DC charger for that if you want. powerstream makes a 7.5amp one and promariner makes a 40(45?)amp one. Each charge source is wired to the battery terminals (or bus bar connected by large gauge wiring thus essentially connected to the terminals).

 

[Dan Grec]

Because a solar panel at full power can be putting out 17-18V+, a tiny panel (IE those little 5-10watt deals) the battery would likely be fine but that isn't going to do well on a large battery. I suspect it'd likely over charge and cause an AGM to outgass, don't know for a fact just suspect it, and if that happens your battery life/capacity will be drastically reduced.

You charge controller has nothing to do with the alternator, they're completely independent and no you can't use one to condition altenator voltage. You need a DC-DC charger for that if you want. powerstream makes a 7.5amp one and promariner makes a 40(45?)amp one. Each charge source is wired to the battery terminals (or bus bar connected by large gauge wiring thus essentially connected to the terminals).

Hmm. Thanks.

I ask about charging the battery because I know many people have the setup where when the engine is running, the alternator changes the aux battery, but when the engine is off, that circuit is cut so the primary vehicle battery will not be drained by aux devices (sorry, I don't remember the name for that setup).
I'm curious about this because if you wire the alternator to the aux battery, it will "overcharge" the aux battery the same way a solar panel will.
If a charge controller is really needed, then surely one is needed for the solar panel AND the alternator charging circuit.

-Dan

 

[dwh]

any suggestions on a kit with a slighly higher standard of panel and controller - any vendor recommendations. I've been burned once buying a cheap fridge, the Edgstar, so willing to spend a bit more at the beginning to have trouble free operation.

Morningstar is one of the top manufacturers of solar charge controllers. Maybe even THE top manufacturer. No worries there. They, and others, do make more expensive controllers, but they generally aren't worth the money for a sub-200w solar array.


Solar panels are all crap when it comes to watts harvested per square foot. There are some that have a slight (like 2% or 3%) higher harvest, but they cost a good deal more and usually aren't worth the money unless you are deploying a couple of acres of them.


The only real issue with the Chinese stuff is whether the aluminum frame is flimsy. Some are, but it's easy to beef up the mounting to add a little extra support.

 

[dwh]

Hmm. Thanks.

I ask about charging the battery because I know many people have the setup where when the engine is running, the alternator changes the aux battery, but when the engine is off, that circuit is cut so the primary vehicle battery will not be drained by aux devices (sorry, I don't remember the name for that setup).

If it's done with a diode-type isolator, it's called a battery isolator.
It it's done with a solenoid, it's usually called a split-charge relay - though some also call it an isolator.

I'm curious about this because if you wire the alternator to the aux battery, it will "overcharge" the aux battery the same way a solar panel will.

Nope.
A diode isolator has a voltage drop through the diode, so in fact, the aux battery will always be slightly undercharged.
With a split-charge relay, the batteries are tied into a single bank, and both are charged to the exact same voltage.

If a charge controller is really needed, then surely one is needed for the solar panel AND the alternator charging circuit.

A charge controller is needed to keep the solar panel from overcharging the battery. IF the solar panel is big enough to overcharge the battery. A little panel and a huge battery usually won't have a problem - other than the problem of the little panel will never get the battery charged.

An alternator is controlled by a voltage regulator. The voltage regulator turns the alternator on when the voltage of the "12v bus" (the whole 12v system - battery, wires, loads, etc.) drops to around 13.5v, and turns the alternator off when the voltage of the bus rises to around 14.5v.

An alternator/voltage regulator setup is not designed to be a good battery charger, and it isn't. It's designed to hold the voltage at a certain level, and when it does, a little juice trickles into the battery to replace what was lost when the engine was started.

To recharge a low aux battery with that setup, you'll have to drive all day.

Or, get a DC-DC charger which IS a good battery charger and gets its power from the 12v bus that the alternator is supplying.

There are also special "battery charging" voltage regulators available.

 

[zidaro]

Been running a 100W panel from AM Solar and their Mounts for 2 years on the top of my Northstar popup. Love the panel and mounts too. We have beat them up on hundreds of miles of off-road and theyve seen crazy desert high winds at highway speeds without ever giving any issue. Not to mention 2 Winters of Sierra snow loads and monster pinecone drops.
I also run a Morningstar sunsaver MPPT 15L charge controller that has never let me down.
Lights, ARB fridge, Stereo, h20 pump, whatever we want- if we have sun our battery is charged.
AM Solar is great, check the prices at http://www.solar-electric.com/ for charge controller stuff too

 

[dags]

is it worth buying a solar panel tilt system for the roof?

 

[timber]

Make it removable so you can pull it down and track the sun if you are base camped for a couple days, easier and more efficient than a movable roof mount. Plus you can park in the shade and put the panel out in the sun.

 

[dags]

Thanks to all for the great advice!!!!


Anyone got roof photos showing the location of their installs for a FWC or ATC?

I was thinking of putting a 125W panel at the front of the camper on the cabover part

 

[Pest]

Thanks to all for the great advice!!!!


Anyone got roof photos showing the location of their installs for a FWC or ATC?

I was thinking of putting a 125W panel at the front of the camper on the cabover part

The best place to locate a panel is where you will have the shortest amount of cable between the panel and charge controller or battery. Longer cables of equal wire gauge will produce a small voltage drop. You would have to get larger gauge wire or just shorten the distance for the best performance.

 

[bobDog]

Hmmm.....this is great info for me so I have a question I have never seen asked ......what about hail? from my LS670 using Tapatalk 2

 

[dwh]

Tempered glass. Pretty tough to break. Takes a really serious hail to do it.

 

[pods8]

I was thinking of putting a 125W panel at the front of the camper on the cabover part

Plan for gas shocks to help lift the roof if you don't already have them with a panel hanging out there, probably will weight about 30lb.

 

[dags]

Plan for gas shocks to help lift the roof if you don't already have them with a panel hanging out there, probably will weight about 30lb.

I will probably end up getting the Gas shocks - i did however put 27lbs of weight on the roof, was not too bad to pick up.

 

[Jeff Wanamog]

What year is your camper? The reason I ask is the later campers already have the cables run to the roof and with your id#, FWC can tell you exactly where to drill to find them. That is why almost all of your FWC & AT campers have the panels mounted in front of the roof vent.
FYI, I am running a 125 watt panel with a Blue Sky MPPT controller on my Eagle. But, I also have two 80 amp hour batteries. I have never had any problems and my isolator between the truck and camper has never worked so I do not charge off of the truck.
Here is a shot of the trailer I am building so you can see the mounting.

It is as simple as attaching 2" X 2" X 1/8" aluminum angle to the perimeter of the panel and then locating the roof supports of the camper.
Use sealant under the angle where you will be attaching to the roof and then on top of the screws.

Jeff