I'm building out a camper van with a solar powered electrical system.

My electrical knowledge is limited to a collage physics and an embedded systems class, so I would really appreciate it if I could get some feedback on a diagram I put together.

Campervan DC Solar Setup

System Overview:

  • 1x 100 watt dc solar panel (may expand to 300 watt in future)
  • EPEver Tracer MPPT 20a charge controller
  • 2x 110 amp AGM/SLA 12v batteries
  • DC water pump (without pressure switch)
  • Shurflo Switch Faucet
  • Various LED lights
  • USB charger
  • Black and Decker power inverter (might upgrade to sine-wave)

Key notes:

  • batteries connected in parallel
  • breaker switch to kill input from solar
  • master switch to kill output to peripherals
  • plan on using a fuse block between all peripherals


Is there anything blatantly wrong with my configuration?

Does it matter how I connect the positive inputs and outputs to my battery bank?

  • Should they just go directly to one of the terminals of the battery?
    • If so, which battery (one is much newer than the other)?
  • Or can I create a master pole in-between the two batteries?
  • Can the Input and output be connected to the same point?
  • 1
    \$\begingroup\$ Remember bypass diodes on each panel, and on battery to prevent it discharging into your panels. What software did you use to make your diagram? \$\endgroup\$
    – user400344
    Commented Dec 9, 2016 at 19:09
  • \$\begingroup\$ @user400344 lucidchart.com. Any additional information on where the bypass diodes exactly diodes should go? or specifically which one I should buy? An amazon search brought me to these: amazon.com/Toolmall-Schottky-Blocking-Diodes-15SQ045/dp/… \$\endgroup\$
    – NSjonas
    Commented Dec 9, 2016 at 19:14
  • \$\begingroup\$ @NSjonas you are asking a big multi facetted question (that to someone in the know will understand) but, the first thing mentioned is bypass diodes on the SPs and you are struggling to understand what the person is talking about. This might take X amount of time in explaining to you (yet to be done). But, there are 9 other major blocks in your diagram to potentially explain the pitfalls of, and this makes anyone thinking about answering think again. This question appears to be too big in relation to your lack of knowledge so maybe restrict it to smaller chunks. \$\endgroup\$
    – Andy aka
    Commented Dec 9, 2016 at 20:27
  • 1
    \$\begingroup\$ You need two vital things to protect your batteries. The MPPT must not overcharge them. I notice the MPPT you specify is 'smart', make sure you've programmed it correctly to not trash your batteries. Second you need an under-voltage lockout on your loads so you don't over-discharge the batteries, 11v is an absolute minimum, you might want to go higher. You might want to split your batteries, and keep one with a higher 'reserve' voltage than the other, depending on your paranoia and mission criticalness. Otherwise, can't see much wrong with it. \$\endgroup\$
    – Neil_UK
    Commented Dec 9, 2016 at 20:42
  • 1
    \$\begingroup\$ @NSjonas You don't need bypass diodes that is for a multiple panel series configuration. You probably do not need a reverse feed protection diode this is usually taken care of in the controller. Just make sure the controller is a reasonable quality true MPPT, there is a lot of Chinese rubbish on the market which claims to be MPPT and isn't. \$\endgroup\$
    – RoyC
    Commented Jan 10, 2017 at 11:13

1 Answer 1


The MPPT that you listed looks like it will work fine if set up properly. To answer your questions:

  • No, it does not matter how the wires are connected on each terminal of the batteries. Voltages are the same for an entire NODE, thus it does not matter what orientation the wires are connected.

Other than that, and as long as you are careful, your setup should work just fine.


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