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Cloning: Small cabin 800W 24V

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= -4F. Coldest clear morning your site sees; cold raises panel voltage.

Solar array

Panels + how they are wired (series x parallel)

Newpowa 200W 12V Monocrystalline Solar Panel (NPA200S-12J, 10BB)
200W, Voc 24.34V, Isc 10.31A
4 panels, 800W total

Charge controller

MPPT/PWM between array and battery

EPEver Tracer 6415AN 60A MPPT
MPPT, 150V max PV, 60A, 12/24/36/48V banks

Battery bank

Identical batteries in parallel

EG4 LifePower4 V2 24V 200Ah
25.6V 200Ah LIFEPO4, BMS 200A
5.1 kWh total

Inverter / all-in-one

DC to AC. All-in-one units include the charge controller.

Victron Energy MultiPlus-II 24/3000/70-50 120V
inverter/charger, 24V, 2400W (5500W surge)

Wire runs

One-way distances for wire and fuse sizing.

SegmentContinuousRun (one way)Copper wireV-dropFuse/breaker
Array to charge controller20.6A50 ft6 AWG1.96%30APV-rated (gPV) fuse or DC breaker
Charge controller to battery bank60.0A8 ft4 AWG0.93%80AClass T
Battery bank to inverter93.8A5 ft1 AWG0.45%125AClass T
Array to charge controller: show the math
Continuous current = 20.6A
Design current = 20.6A x 1.25 (NEC continuous) = 25.8A
Wire: 6 AWG copper (75C ampacity 65A); voltage drop 1.96% over 100ft round trip at 41.5V (target <= 3%)
Fuse/breaker: 30A - two criteria, both required:
  carry the load: fuse >= design 25.8A -> next standard size = 30A
  protect the wire: fuse 30A <= 6 AWG ampacity 65A - OK
  construction: PV-rated (gPV) fuse or DC breaker
Charge controller to battery bank: show the math
Continuous current = 60A
Design current = 60A x 1.25 (NEC continuous) = 75A
Wire: 4 AWG copper (75C ampacity 85A); voltage drop 0.93% over 16ft round trip at 25.6V (target <= 3%)
Fuse/breaker: 80A - two criteria, both required:
  carry the load: fuse >= design 75A -> next standard size = 80A
  protect the wire: fuse 80A <= 4 AWG ampacity 85A - OK
  bank BMS continuous 200A >= fuse 80A: the bank can hold the fuse's rated load
  construction: Class T (interrupt rating matters on battery mains)
Battery bank to inverter: show the math
Continuous current = 93.8A
Design current = 93.8A x 1.25 (NEC continuous) = 117.2A
Wire: 1 AWG copper (75C ampacity 130A); voltage drop 0.45% over 10ft round trip at 25.6V (target <= 3%)
Fuse/breaker: 125A - two criteria, both required:
  carry the load: fuse >= design 117.2A -> next standard size = 125A
  protect the wire: fuse 125A <= 1 AWG ampacity 130A - OK
  bank BMS continuous 200A >= fuse 125A: the bank can hold the fuse's rated load
  construction: Class T (interrupt rating matters on battery mains)

Mount the fuse close to the battery positive terminal - it protects the wire run, so the unprotected stub should be as short as possible.

Sized for 75C copper ampacity with the NEC 1.25 continuous factor and a 3% voltage-drop target. Round up when between sizes and verify against local code.

Balance of system - shopping list

ItemQtyFor
6 AWG copper wire1~115 ft total (50 ft one way, round trip + slack) - Array to charge controller
30A PV-rated (gPV) fuse or DC breaker1Array to charge controller
4 AWG copper wire1~20 ft total (8 ft one way, round trip + slack) - Charge controller to battery bank
80A Class T1Charge controller to battery bank - include the matching fuse holder/block
1 AWG copper wire1~15 ft total (5 ft one way, round trip + slack) - Battery bank to inverter
125A Class T1Battery bank to inverter - include the matching fuse holder/block

Derived from the wire and fuse guidance above. Wire lengths include round trip plus slack - verify against your actual layout, and verify ratings against local code. Buy fuses and wire from reputable electrical suppliers; marketplace listings for these items are a common source of counterfeit or mislabeled parts.

Parts list

PartQtyEst. priceWhere to buy
Newpowa 200W 12V Monocrystalline Solar Panel (NPA200S-12J, 10BB)
panel2 in series x 2 stringsdatasheet
4$560
EPEver Tracer 6415AN 60A MPPT
controllerdatasheet
1$250
EG4 LifePower4 V2 24V 200Ah
batterydatasheet
1$1,199
Victron Energy MultiPlus-II 24/3000/70-50 120V
inverterdatasheet
1$997
Estimated total$3,006
1 warning - review before buying12 passed / 0 errors / 1 warning / 0 notes / 1 not checkable
warningBank peak current limit unpublished - surge headroom unverifiedInverter surge vs battery peak limit

The Victron Energy MultiPlus-II 24/3000/70-50 120V can surge to 5500W (214.8A at 25.6V). EG4 LifePower4 V2 24V 200Ah does not publish a BMS peak discharge rating, so we cannot verify motor-start surges will not trip the BMS.

surge 5500W / 25.6V = 214.8A; BMS peak limit unpublished
12 passing checks - expand to see the math
passBattery matches the 24V systemSystem voltage coherence

EG4 LifePower4 V2 24V 200Ah (25.6V nominal) is a 24V-class battery.

battery nominal 25.6V is in the 24V class == system 24V
passInverter matches the 24V systemSystem voltage coherence

Victron Energy MultiPlus-II 24/3000/70-50 120V DC input is 24V-class.

inverter DC input 24V is in the 24V class == system 24V
passCharge controller supports 24V banksSystem voltage coherence

EPEver Tracer 6415AN 60A MPPT supports 12/24/36/48V battery banks.

controller battery voltages [12, 24, 36, 48] include 24V
passString Voc stays at 56.6V at -20C - cannot reach the 150V limit at any temperatureCold-temperature string voltage

2 x Newpowa 200W 12V Monocrystalline Solar Panel (NPA200S-12J, 10BB) in series stays below the EPEver Tracer 6415AN 60A MPPT max PV input voltage at your design low temperature. This string cannot reach 150V at any physically possible temperature.

Why this matters: Panel voltage rises as temperature falls. A string that measures fine in summer can exceed the controller's absolute maximum input voltage on the first cold clear morning, which can permanently destroy the controller - and at these DC power levels, failures can start fires. This is the mistake experienced builders catch most often in DIY parts lists.

Voc_string = Voc x N_series x (1 + tempCoeff/100 x (T_design - 25))
          = 24.34V x 2 x (1 + (-0.36%/100) x (-20 - 25))
          = 24.34V x 2 x 1.1620 = 56.6V
Controller max PV input: 150V
Crossover: string Voc reaches 150V at T = 25 + (150/48.7 - 1) x 100/-0.36 = -553.2C (below absolute zero - never reached)
passString Vmp 41.5V has healthy margin over the 24V bankMPPT voltage margin

Clears the start floor cold and the hot-weather floor with sag included.

Vmp_string = 20.74V x 2 = 41.5V
Start floor = V_batt + 5V = 24 + 5 = 29V
Hot Vmp (~11% sag) = 41.5V x 0.89 = 36.9V vs hot floor 32V
passController can pass the array's full output (31.3A of 60A rated)Array size vs controller charge output

No clipping at rated conditions.

Array = 200W x 4 panels = 800W
Potential charge current = 800W / 25.6V = 31.3A
Controller rated charge current: 60A
passArray 800W is within the controller's 1500W rating at 24VMax array wattage for battery voltage

Within the published maximum array wattage.

Array = 200W x 4 panels = 800W
Controller max array wattage at 24V: 1500W
passEPEver Tracer 6415AN 60A MPPT supports LiFePO4 chargingBattery chemistry support

Controller has a lithium profile or user-adjustable charge voltages.

battery chemistry = lifepo4; controller lifepo4_profile = true
passVictron Energy MultiPlus-II 24/3000/70-50 120V charger supports LiFePO4Battery chemistry support

Inverter/charger has a lithium charge profile.

battery chemistry = lifepo4; inverter charger lifepo4_profile = true
passBank BMS limit 200A comfortably covers the inverter's 93.8A drawInverter draw vs battery BMS limit

Healthy headroom at full inverter load.

Inverter draw = 2400W / 25.6V = 93.8A
Bank BMS limit = 200A x 1 batteries = 200A
Headroom band starts at 80% of limit = 160A
passCharge current 60A is within the bank's 200A capacityCharge current vs bank capacity

Charge rate within limits.

Controller rated charge = 60A
Bank max charge = manufacturer max charge 200A x 1 = 200A
passClosed-loop comms available via generic-canClosed-loop battery communications

The inverter can read state of charge and limits directly from the battery BMS. Enable closed-loop per both manuals.

inverter speaks [victron, pylontech, generic-can]; battery speaks [eg4, generic-can, rs485]; overlap [generic-can]
1 check not run (missing published specs)
not checkedNot checkedArray current vs controller input limit

EPEver Tracer 6415AN 60A MPPT does not publish a PV input current limit in our data. MPPT controllers generally current-limit safely, but verify against the manual.

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