system design

wastwast Posts: 33Registered Users ✭✭
2 x 24 volt agm batteries @170 ah.. 40 amp mttp charge controller.. 2 190 watt solar panels in series.. 1500 watt aims pure sine wave inverter... 26 amp 24 volt 3 stage charger for use when batteries need charging... system to be used for refrigerator only.. refrigerator is a 10 cu ft danby with a 297 kwh rating... weekend cabin.. need help with wire sizing and fuse sizing and anything else that is needed... will add more panels in future to whatever charge controller can accommodate... I have 2 gravity feed water systems at camp that I may be able to configure into system with a small micro system is for camp water and the other I have to irrigate small garden as needed but most of the time is running freely and has about 50 psi... 


  • EstragonEstragon Posts: 2,431Registered Users ✭✭✭✭
    Wire and fuse/breaker sizes should be as spec'd by inverter and controller manuals. Wire size from panels to controller depends on distance and current. Using a voltage drop calculator online, you can figure out what size wire is needed for something like a 3% voltage drop. For current, use the current (Imp) you'll eventually have with the string config with the controller maxed out.

    You don't need it now, but will likely need a combiner box to parallel multiple strings later. My preference is to use breakers vs fuses as the make handy disconnects, and don't need to keep spare fuses.

    Don't know much about microhydro. 50psi sounds like enough head, so if you can measure GPM you should be able to figure viability.
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • mcgivormcgivor Posts: 1,878Solar Expert ✭✭✭✭
    When installing an electrical system it is usually wise to provide room for future expansion, more so if that is what is projected. Electrical rules and regulations are based on minimum requirements, this doesn't mean over sizing is unacceptable, in fact in the case of conductors it's benificial to install larger than required, especially when dealing with low voltage.

    Points to remember, overcurrent protection is for the sole purpose of protecting the conductors, not the devices connected to them, when using circuit breakers which are polarized the input should be connected to the source with the highest energy potential, batteries are an extremely high potential, pay attention to this when using a circuit breaker connected to a battery.

    Without distances between components being known, it is impossible to suggest  conductors which would be appropriate, as well as the overcurrent protection needed to protect them, more details would be helpful.
      1500W, 6× Schutten 250W Poly panels , Schneider 150 60 CC, Schneider SW 2524 inverter, 8×T105 GC 24V nominal 

  • wastwast Posts: 33Registered Users ✭✭
    distance from battery to inverter will be less then 3 ft... I plan on using 2/0 wire with a 150 amp fuse and a quick disconnect key..From panels to controller will use 10awg multi strand (approx. 15 ft) and from controller to batteries will use 6awg (about 4 ft).. refrigerator will be pluged directly into inverter and will be able to plug to generator when gen set in use
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