Solar electrical diagram critique

Hello all,

This is my first post here. I am in the early stages of building out a promaster, and I am getting ready to start installing/connecting all my electrical components. I already have my solar panels installed on the roof (3 100w monocrystalline panels wired in series). I have already purchased my charge controller, inverter, and batteries. I have been researching like crazy to learn how to hook everything up. I put together a diagram of what I THINK will work, but I would really appreciate feedback and/or critiques on it. Anything that is incorrect, redundant, or if I’m missing something completely. Please disregard the directions of the arrows in the diagram, I meant for those to just be straight lines.

Thanks,
Eric

Greetings!

300 watts of solar is barely enough for a 100ah of battery in the winter, except maybe in the desert. With a 400 ah battery bank, you’ll want a bare minimum of 800 watts of solar. Hours of usable sun are less than half in the winter, not even taking into account cloudy or stormy weather.

Regardless of how much solar you have, I wouldn’t be caught dead without my generator. My $99 generator guarantees that rain or shine, or even darkness, I can always have power and properly charge my batteries, even when shore power isn’t available.

Your fuse block should be connected directly to your battery bank, not the controller, and each line to/from your battery bank needs a fuse or circuit breaker directly off your battery bank, before anything else.

Cheers!


"Smiles are contagious, pass it on!" ~ Van_Dweller


Thanks for the tip about connecting fuse block directly to batteries. Unless I misunderstood what you meant, I believe I do have a fuse or breaker first off the battery bank between everything connected. I guess I’d just need to add a fuse between the battery bank and fuse block then.

I do plan to have a small generator. Can I just plug the output of generator into the input of my shore power outlet?

Greetings!

Yes, you can plug your generator in that way.

I went cheaper with a $29 battery charger instead of a converter charger. It’s portable, so I can also use it and the generator to charge my starting battery if needed, plus it is handy to charge other people’s batteries, which is where it gets most of it’s use.

I ditched the solar, in favor of just charging while driving, and 99.9% of the time that’s all I ever need unless I’m camped out and not moving for over a couple of weeks. Then my generator & battery charger earn their keep. Since I refuse to park in the sun during the summer, solar never worked for me.

Cheers!


"Smiles are contagious, pass it on!" ~ Van_Dweller


(novice speaking here) This seems to be crazy expensive and complicated to me. But if you have a promaster you can probably afford it. We do not have an inverter and haven’t had the need for one yet although we plug in a lot. I am ready to rip the charger/converter out of my old van entirely and simply replace it with a promariner/prosport charger (http://www.promariner.com/en/43020). Not sure of the implications yet or if I need to do anything to plug it in to my 30amp connection. Although, I don’t think I will. I had great success with these chargers on my old sailboat. I guess I don’t see the need for a converter/charger combo, but I do not know a lot about this yet and am still learning.

Are you going to use the body of your vehicle to complete the circuit? My van does and I do not like it, I would rather run the negative back to its source or back to a fuse panel.

Also not that it is wrong but why would you run the fuse block off or your solar charge controller and not off of the battery bank itself? I’m adding in a monitor this week (https://www.renogy.com/500a-battery-monitor/), but for it to work correctly all negatives hook to it then it hooks to the batter. Wondering how this would work in this setup and how you are going to monitor actual amps in and out or amp hours total? This to me is the most important part of it all and it seems like you’re missing it unless one of these devices does that already?

Greetings!

Rather than worrying about amps in/out, I have battery protectors that will automatically cut off the batteries if they get too low. I have one on my house battery, and one on my starting battery as well. My starting battery is also a deep cycle battery, and I get about a week out of each battery (used separately). Even after cut-off, the starting battery still has plenty of power to start my rig.

In my life, worrying about my power system constantly is a huge waste of time, so I keep things as simple as possible, and basically never run out of power. Normal city driving every few days usually keeps my house battery happy, but if I’m out camping for longer than a couple of weeks without driving, I have a generator to charge my batteries with an el cheapo $29 house style automatic battery charger. “Automatic” is the key word here, it will never over charge a battery, so it doesn’t need constant babysitting.

Cheers!


"Smiles are contagious, pass it on!" ~ Van_Dweller


Taking some of the suggestions I got, I updated my diagram to reflect a few changes.

I have a couple of follow up questions now:

  1. For the batteries other things that need to be physically grounded to the vehicle, can those all share the same ground location/screw? Or should they all be separate? Also, should the gauge of that vehicle ground wire be the same as the ones that connect it to the battery?

  2. What’s the best way to decide what size fuse to use between the 12v fuse block and battery?

Greetings!

You size your wires according to the power they need to carry, you size your fuses according to capacity of the wires. Your fuse should be at least 10% lower than wire capacity, 20-25% even better.

Cheers!


"Smiles are contagious, pass it on!" ~ Van_Dweller


I do not understand the whole fuse sizing thing myself. I believe I read once that if you have something that pulls 5 amps you need a 15 amp fuse. Essentially 3x the draw, but I think that might simply be wrong (as most info on the internet these days). One thing to maybe look at is something like this instead of fuses though, it might save you some money as you won’t have to replace them over and over as they don’t burn out:

https://www.delcity.net/store/12V-Auto-Reset-Circuit-Breakers/p_198669.h_198847.r_IF1003?mkwid=sIDeGB8L5&crid=38094426869&mp_kw=&mp_mt=&gclid=EAIaIQobChMIpfarhprq5AIVAeDICh3PjA0nEAQYASABEgLAxvD_BwE

Essentially when there is an overload this will trip and attempt to reset itself over and over until the load is gone. My van camper was built in 83’ and they installed these between my isolator and my battery. I have 100 amp alternator and they used a 30 amp breaker. There is also one between my battery and my shore charger/converter. You can easily tell if they are tripped by testing continuity from pole to pole.

Hope this helps and good luck.

Greetings!

Fuses are meant to prevent too much power going through the wire, where it will heat up and possibly melt and start a fire. Dead shorts can cause this, as well as something trying to draw more power than wire was designed to carry.

Cheers!


"Smiles are contagious, pass it on!" ~ Van_Dweller


Hey Eric,
Looks like a great set up, thank you for posting your diagram. I just bought a Promaster and am looking at an almost identical set up, though I’m not using Gel batteries simply because of expense. Please post a follow up on whether this set up is everything that you had hoped for. I’ve seen several people that have diagrams with the fuse box coming out of the charge controller…more info on whether it should be that way or out of batteries would be appreciated, it’s very con-fuse-ing.
Travis

Greetings!

There should be a fuse between the controller and the battery(s), but the fuse box and ALL loads should always hooked up to the battery, not the controller.

Cheers!


"Proper Planning is preferable to premature failure" ~ DreamLife


300W of panels will be plenty if you drive around a little bit as the fuel battery system charges the second battery a lot lot quicker than the solar system will. Also, instead of a 150a battery isolator (which is not overly efficient) and use a continuous duty solenoid. You just connect it to a windscreen wiper wire or radio or something that draws power when the key is turned. This way the second battery will be connected when driving but disconnected when you are not. You will have way less energy loss this way. Hope that makes some sense. I’ll try draw up a diagram if not.