Cloning: Backup blackout kit 24V
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Solar array
Panels + how they are wired (series x parallel)
Charge controller
MPPT/PWM between array and battery
Covered by your all-in-one: Growatt SPF 3000TL LVM-24P includes MPPT charging.
Battery bank
Identical batteries in parallel
Inverter / all-in-one
DC to AC. All-in-one units include the charge controller.
Wire runs
One-way distances for wire and fuse sizing.
| Segment | Continuous | Run (one way) | Copper wire | V-drop | Fuse/breaker |
|---|---|---|---|---|---|
| Array to all-in-one PV input | 8.9A | 25 ft | 14 AWG | 1.49% | 15APV-rated (gPV) fuse or DC breaker |
| Battery bank to all-in-one | 117.2A | 5 ft | 1/0 AWG | 0.45% | 150AClass T |
Array to all-in-one PV input: show the math
Continuous current = 8.9A Design current = 8.9A x 1.25 (NEC continuous) = 11.2A Wire: 14 AWG copper (75C ampacity 20A); voltage drop 1.49% over 50ft round trip at 75.7V (target <= 3%) Fuse/breaker: 15A - two criteria, both required: carry the load: fuse >= design 11.2A -> next standard size = 15A protect the wire: fuse 15A <= 14 AWG ampacity 20A - OK construction: PV-rated (gPV) fuse or DC breaker
Battery bank to all-in-one: show the math
Continuous current = 117.2A Design current = 117.2A x 1.25 (NEC continuous) = 146.5A Wire: 1/0 AWG copper (75C ampacity 150A); voltage drop 0.45% over 10ft round trip at 25.6V (target <= 3%) Fuse/breaker: 150A - two criteria, both required: carry the load: fuse >= design 146.5A -> next standard size = 150A protect the wire: fuse 150A <= 1/0 AWG ampacity 150A - OK bank BMS continuous 200A >= fuse 150A: 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
| Item | Qty | For |
|---|---|---|
| 14 AWG copper wire | 1 | ~60 ft total (25 ft one way, round trip + slack) - Array to all-in-one PV input |
| 15A PV-rated (gPV) fuse or DC breaker | 1 | Array to all-in-one PV input |
| 1/0 AWG copper wire | 1 | ~15 ft total (5 ft one way, round trip + slack) - Battery bank to all-in-one |
| 150A Class T | 1 | Battery bank to all-in-one - 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.
12 passing checks - expand to see the math
passBattery matches the 24V systemSystem voltage coherence
LiTime 24V 100Ah LiFePO4 (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
Growatt SPF 3000TL LVM-24P DC input is 24V-class.
inverter DC input 24V is in the 24V class == system 24V
passString Voc stays at 96.8V at -15C - safe down to -226.7C (-376.1F)Cold-temperature string voltage
2 x Renogy 320W Monocrystalline Solar Panel (RSP320D) in series stays below the Growatt SPF 3000TL LVM-24P max PV input voltage at your design low temperature. The string would not reach the 145V limit until the temperature drops below -226.7C (-376.1F).
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))
= 43.82V x 2 x (1 + (-0.26%/100) x (-15 - 25))
= 43.82V x 2 x 1.1040 = 96.8V
Controller max PV input: 145V
Crossover: string Voc reaches 145V at T = 25 + (145/87.6 - 1) x 100/-0.26 = -226.7CpassString Vmp 75.7V has healthy margin over the 24V bankMPPT voltage margin
Clears the start floor cold and the hot-weather floor with sag included.
Vmp_string = 37.85V x 2 = 75.7V Start floor = V_batt + 5V = 24 + 5 = 29V Hot Vmp (~11% sag) = 75.7V x 0.89 = 67.4V vs hot floor 32V
passController can pass the array's full output (25A of 80A rated)Array size vs controller charge output
No clipping at rated conditions.
Array = 320W x 2 panels = 640W Potential charge current = 640W / 25.6V = 25A Controller rated charge current: 80A
passArray 640W is within the controller's 2000W rating at 24VMax array wattage for battery voltage
Within the published maximum array wattage.
Array = 320W x 2 panels = 640W Controller max array wattage at 24V: 2000W
passGrowatt SPF 3000TL LVM-24P supports LiFePO4 chargingBattery chemistry support
Controller has a lithium profile or user-adjustable charge voltages.
battery chemistry = lifepo4; controller lifepo4_profile = true
passGrowatt SPF 3000TL LVM-24P 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 117.2A drawInverter draw vs battery BMS limit
Healthy headroom at full inverter load.
Inverter draw = 3000W / 25.6V = 117.2A Bank BMS limit = 100A x 2 batteries = 200A Headroom band starts at 80% of limit = 160A
passBank BMS peak 560A covers the inverter's 234.4A surgeInverter surge vs battery peak limit
Surge loads within the bank's published peak rating.
Surge draw = 6000W / 25.6V = 234.4A Bank BMS peak = 280A x 2 batteries = 560A
pass2 in parallel is within the manufacturer limit of 4Battery parallel count
Supported parallel configuration.
2 in parallel vs manufacturer max 4
passCharge current 80A is within the bank's 200A capacityCharge current vs bank capacity
Charge rate within limits.
Controller rated charge = 80A Bank max charge = manufacturer max charge 100A x 2 = 200A
2 checks not run (missing published specs)
not checkedNot checkedArray current vs controller input limit
Growatt SPF 3000TL LVM-24P does not publish a PV input current limit in our data. MPPT controllers generally current-limit safely, but verify against the manual.
not checkedNot checkedClosed-loop battery communications
Comms protocols for LiTime 24V 100Ah LiFePO4 are not in our data. The system will still work open-loop with manually set charge voltages.
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