Solar Design Attached / Comments?


New Member
Oct 21, 2020
Location: Western WA State / US
48v 10.4 kw battery:
Purpose: Emergency backup
Expect to move in next few years and plan to bring components with me toward full off-grid location. Want to expand the system accordingly thru linking inverters to increase power.

a) Backup / emergency power
b) Critical loads: esp in winter: 2 sump pumps. Heat: furnace carriage fan (gas furn)
c) Lights/Fridge/Freezer
Assuming dedicated/separate AC circuits attached to support critical loads.

1st Phase:
  1. (4) 435w 49.7 Voc / 40.5 Max Output volts) each. Bifacial, Half-cut Solar Panels. 3h direct sun; neighbors trees shade differently depending on season. Expect to produce bulk of power during that period. If 4 panels don't cut it, then will add 2 more.
  2. (2) x (2) Panel in-series. ~100v 10.5amps per series/circuit. Grounded panels.
  3. Each panel as NEC compliant 2020 Rapid Shutdown
  4. Combiner Box (3 in, 3 out for expansion)
    1. Each Circuit will have it's own DC breaker (Sizing: 120v 25-30a)
    2. Doubles as PV isolation - shut off each series to isolate
    3. Questions: Looking for a combiner box with 1 'shutdown' switch for immediate manual control, + Lightning Voltage Spike protection. Good quality, midrange price. What are you using? UL certified?
      1. My muni uses NEC2020. Q: Does this require UL cert on components?
  5. Each circuit goes to 100v/35a MPPT (atm Victron is assumed but pricey)
  6. Shutoff between MPPT and Battery.
    1. Q: Do I need a fuse here? 60v?
    2. Shut off switch capacity? 60v?
  7. Inverter charger. Your thoughts welcomed:
    1. Victron Multiplus II: 48v/3000/35a charger; supports combining GEN (syncs) to Honda EU2000 in emergent situation.
      1. Cost
      2. Somewhat concerned about motor startup for sumps (1/2hp) despite surge capacity
    2. Other Suggestions?
  8. Lightning rod / sep grounding rods away from GRID grounding rod.
Hoping the questions will help me and others. Found it difficult to find some components and understanding manufacturers over-charging and/or confusing / possibly misleading / UL and other certifications. Also tried 4 vendors to pay for solar design assistance but couldn't get anyone interested (fully expected to pay). Figured Solar Electrician / Design query on web would help. It didn't...

Thanks much!


  • Solar Design Cloudy Seattle area.pdf
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New Member
Nov 6, 2021
I can help you.

I was looking for a way to send you a private message directly but does this website allow that?