Solar Setup in VW camper- need a bit of advise

Re: Solar Setup in VW camper- need a bit of advise

Welcome to the forum Kevin!

Sorry for the late reply--Lots of stuff here. Let me see what I can do.

VW Kevin wrote: »

My questions are this: I've used the Perko through deck connector in the past and like it okay, but a sleek junction box may better suite my needs. It would keep everything mc4 and give me the option to remove the panel and add an extension cord if I don't want to park in the sun. I've tried researching a proper box that has option for 2 inputs and one output into the van. The tricky part here is I can't have any vertical inputs or outlets. Am I asking too much??

I am not sure I would use those Perko connectors... Depending on the actual panels you use and how they are wired up--You can see 10+ amps and 12-10 AWG cable--I don't think those connectors would take that amount of current or gauge of cable.

You might be better off with an access door that you can feed plugs/cables through.

An option would be a twist lock AC cord with rain cap (or similar--Twist lock to avoid plugging in standard shore power to DC circuits). You can get some pretty heavy duty plug sets (but they will not be cheap either).

Note that MC4 Connectors are not really designed to mate/break for a maximum of 100 cycles before they "wear out".

R&R'ing the panels from your roof--These are usually ~1/8" tempered glass. If you do move the panels around--Be very careful. Tempered glass is pretty tough until it breaks (scratches/chip a corner, etc.). At that point, the entire surface of the panel will usually shatter--Just like safety glass.

If you do make the panels removable--Make the mounting easy to do (if one person, you may not want panels much larger than ~140 Watts as larger panels will need to people to safely move about)--Plus you need a ground stake/framework/etc. to make sure the panels do not blow down and break.

Also, I'm interested in knowing more about placement of circuit breakers/ fuses. Inverter has built in protection, I've got a fuse panel with a breaker in between it and the aux battery, but that's all.

Lead Acid (and other) battery banks are very capable of 100's of amperes into a dead short. Every cable that leaves the positive battery bus should have a fuse or circuit breaker sized to the gauge of the wire--To prevent the wires from catching fire if there is short circuit somewhere.

For those who want more info on my setup design, here it is:

•Incoming Power source 1-(DC) -- alternator brings in power to the starting battery, it then will go through a Sure Power 1314 uni-directional combiner to then charge the house battery as well- house battery: most likely a Lifeline GPL-27T deep cycle, mil spec, AGM sealed house battery.

A 100 AH @ 12 volt battery for house power. AGM's are nice batteries.

Using the vehicle's alternator can help charge the house battery when driving--But monitor the actual charging voltage and current to the house battery. Alternators have been known to back down on the charging current/voltage when they get hot. Deep Cycle AGM batteries usually need around 14.2 to 14.4 volts for a good charge--The typical alternator is probably around 13.8 to 14.2 volts when charging--If the RV's alternator is an important part of your power needs/generation--You may have to revisit and use a marine alternator setup.

•Incoming Power Source 2- (DC)Power comes in from the sun through the 85w panel, through the Perko roof connection, into the charge controller which then has priority to 1 charge the house battery and when full will 2 switch to the starting battery. The tricky thing here was the combiner as most folks use a bi-directional combiner so the priority feature on the charge controller wouldn't function properly as the bi-combiner shares any incoming power from either battery with the other battery. Hence the uni-directional Sure Power. Any power coming to the starting battery will be shared but power coming into the Aux battery will not be passed through... Only works one way.

An 85 Watt panel should have Vmp~17.6 volts and Imp~4.8 amps... That is not very much and may be OK with the Perko connector...

For a 100 AH battery:

• 4.8 amps / 100 AH battery = 0.048 = ~5% rate of charge for the house battery

That is not a lot of charging current--If you could get a 10% to 13%+ rate of charge if you plan on a lot of dry camping--That would be a good idea (something like 2-3x 85 watt solar panels--if you can fit them and they are in your budget.

Charge controller--If you stay with "12 volt" panels, you can use this dual battery charger from MorningStar--Designed exactly for your needs:

SunSaver Dual Battery 25 Amp 12 Volt Solar Charge Controller

•Incoming Power Source 3: Shore power(AC)- plug in the van with an extension cord that goes directly into Dual Pro Charger to charge both batteries.

•Outgoing Power Source A: Main starting battery. It's sole job is to run the vehicle.

•Outgoing Power Source B: Auxiliary house battery. From the 100Ah battery will power the inverter and also will then come the fuse panel. The 6 locations on the panel will be set up for lights, solar panel, roof vent, fridge, and 12v outlets through out the van. House battery to fuse panel has 50A breaker.

I don't have much to say on the AC charger side--There are lots of options out there. Deep cycle batteries do better with a proper charging profile (voltage, time, current, etc.). AGM batteries do not like too high of voltage when charging/floating. They are sealed--And if over charged will vent--And cause them to fail early.

For me--The missing items are your loads--How many Amp*Hours @ 12 volts or Watt*Hours per day are you planning on using.

The 85 Watt panel is pretty much the minimum we would recommend for a deep cycle battery that is not used every day (i.e., weekend RV/cabin vs daily use over the entire year).

• 85 watts * 0.52 AC off grid system efficiency * 4 hours of sun per day (typical 9 month minimum sun in US) = 177 Watt*Hours of energy per day typical minimum

Or:

• 4.8 amps * 4 hours per day sun = 19 Amp*Hours @ 12 volts per day

In summer, you may get 5-6 hours of sun on a good day--But still not much power.

Will you need to run the RV's engine, a genset, or similar to meet your energy usage?

-Bill