1. How to Select a Fuse
For system safety, Renogy recommends installing fuses on both the input and output sides of power equipment to ensure safe operation.
1.1 Device → Solar Panels
Refer to the solar panel user manual for the operating parameters and calculate the fuse rating using the following formula:
Fuse Rating = Isc (or Total Isc) × 1.56, rounded up to the next standard fuse size
You may also refer to the table below:
| Isc (or Total Isc) Range | Calculated Value (Isc × 1.56) | Recommended Standard Fuse |
|---|---|---|
| 0–5 A | ≤ 7.8 A | 10 A |
| 5–8 A | 7.8–12.48 A | 15 A |
| 8–13 A | 12.48–20.28 A | 20 A |
| 13–16 A | 20.28–24.96 A | 25 A |
| 16–19 A | 24.96–29.64 A | 30 A |
| 19–23 A | 29.64–35.88 A | 40 A |
Note: When selecting a fuse, always check the Maximum Fuse Rating listed in the solar panel specifications. The fuse rating must not exceed this value.
Required quantity:
-
Single Panel or Single Series String (No Parallel Connection)
One fuse may be installed on the positive output of the string (optional but recommended). In a series-connected string, current flows through a single continuous path and remains essentially constant throughout the string. Therefore, installing one properly rated fuse at the positive output of the string provides overcurrent protection for the entire string. -
Multiple Panels or Multiple Strings in Parallel
Each string must have an individual fuse installed on its positive output (mandatory). When no more than two strings are connected in parallel, fuses may be omitted (optional but recommended). In parallel configurations, each branch requires independent protection. If one solar panel or sub-array develops a short circuit or fault, healthy branches may feed reverse current into the faulty branch, potentially causing damage or safety hazards. Installing a fuse on the positive output of each parallel branch isolates the fault locally and protects the remaining branches, maintaining safe and reliable system operation.
The following Renogy solar fuses are available for purchase as needed:
- 10 A Fuse (SKU: RNG-CNCT-FUSE10)
- 15 A Fuse (SKU: RNG-CNCT-FUSE15)
- 20 A Fuse (SKU: RNG-CNCT-FUSE20)
- 30 A Fuse (SKU: RNG-CNCT-FUSE30)
1.2 Device → Auxiliary Battery
Installation Location: To ensure the auxiliary battery, especially a LiFePO₄ battery, can reach 100% state of charge, install the equipment as close to the battery as possible. The recommended distance is within 20 cm (7.9 in), and no more than 1.5 m (4.9 ft), to minimize voltage drop during the final charging stage.
| Maximum Charging Current | Recommended Fuse Rating |
|---|---|
| 10 A | 15–20 A Fuse |
| 15 A | 20–25 A Fuse |
| 20 A | 25–30 A Fuse |
| 25 A | 35–40 A Fuse |
| 30 A | 40–50 A Fuse |
| 40 A | 50–60 A Fuse |
| 50 A | 60–80 A Fuse |
| 60 A | 80–90 A Fuse |
| 100 A | 130–150 A Fuse |
The following Renogy ANL fuses are available for purchase as needed:
- 20 A Fuse (SKU: RNG-SET-ANL20)
- 30 A Fuse (SKU: RNG-SET-ANL30)
- 40 A Fuse (SKU: RNG-SET-ANL40)
- 50 A Fuse (SKU: RNG-SET-ANL50)
- 60 A Fuse (SKU: RNG-SET-ANL60)
- 80 A Fuse (SKU: RNG-SET-ANL80)
- 100 A Fuse (SKU: RNG-SET-ANL100)
- 200 A Fuse (SKU: RNG-SET-ANL200)
- 300 A Fuse (SKU: RNG-SET-ANL300)
- 400 A Fuse (SKU: RNG-SET-ANL400)
1.3 Device → Starter Battery
Installation Location: The fuse must be installed on the positive side of the vehicle starter battery, ideally within 20 cm (7.9 in) of the battery terminal.
| Maximum Charging Current | Recommended Fuse Rating |
|---|---|
| 10 A | 15–20 A Fuse |
| 15 A | 25–30 A Fuse |
| 20 A | 30–40 A Fuse |
| 25 A | 35–40 A Fuse |
| 30 A | 50–60 A Fuse |
| 40 A | 60–70 A Fuse |
| 50 A | 70–80 A Fuse |
| 60 A | 80–100 A Fuse |
| 100 A | 150–180 A Fuse |
1.4 Inverter Device → Auxiliary Battery
Installation Location: The fuse must be installed on the positive side of the auxiliary battery, ideally within 20 cm (7.9 in) of the battery terminal. Class‑T fuses are recommended.
Current Calculation: Maximum Current = Inverter Power ÷ System Voltage
Select the fuse rating based on the calculated maximum current.
| Inverter Model | Recommended Fuse Rating |
|---|---|
| 12 V 1000 W | 150 A Fuse |
| 12 V 2000 W | 250 A Fuse |
| 12 V 3000 W | 350 A Fuse |
| 24 V 1000 W | 55–80 A Fuse |
| 24 V 2000 W | 105–160 A Fuse |
| 24 V 3000 W | 160–250 A Fuse |
| 48 V 1000 W | 30–40 A Fuse |
| 48 V 2000 W | 55–80 A Fuse |
| 48 V 3000 W | 80–120 A Fuse |
| 48 V 3500 W | 100–140 A Fuse |
The following Renogy Class‑T fuses are available:
- 150 A Fuse (SKU: RPD150CTF-SET)
- 250 A Fuse (SKU: RPD250CTF-SET)
- 350 A Fuse (SKU: RPD350CTF-SET)
2. How to Select Cables
- Cable Requirements: Use UL‑certified stranded copper cables rated for temperatures above 105°C (221°F). These cables provide superior high‑temperature performance and higher ampacity.
- Fuse‑to‑Cable Matching Principle: The fuse rating must always be lower than the maximum current rating of the cable to ensure complete cable protection. Under overcurrent conditions, the fuse must open before the cable overheats.
- Cable Length Definition: Cable length refers to the total combined length of both the positive and negative cables.
2.1 Device → Battery
Select the cable size according to the fuse rating using the table below. The table assumes a voltage drop of less than 8%. Applicability depends on system voltage, installation environment, and conductor routing.
| Fuse Rating | Cable Length | Recommended Cable |
|---|---|---|
| 15A-20A Fuse | 0-13 ft (0-4 m) | 16 AWG (1.32 mm²) |
| 13-18 ft (4-5.5 m) | 14 AWG (2.08 mm²) | |
| 18-23 ft (5.5-7 m) | 14 AWG (2.08 mm²) | |
| 23-28 ft (7-8.5 m) | 14 AWG (2.08 mm²) | |
| 28-40 ft (8.5-12 m) | 12 AWG (3.33 mm²) | |
| 25A-30A Fuse | 0-13 ft (0-4 m) | 14 AWG (2.08 mm²) |
| 13-18 ft (4-5.5 m) | 12 AWG (3.33 mm²) | |
| 18-23 ft (5.5-7 m) | 12 AWG (3.33 mm²) | |
| 23-28 ft (7-8.5 m) | 10 AWG (5.26 mm²) | |
| 28-40 ft (8.5-12 m) | 10 AWG (5.26 mm²) | |
| 30A-40A Fuse | 0-13 ft (0-4 m) | 12 AWG (3.33 mm²) |
| 13-18 ft (4-5.5 m) | 12 AWG (3.33 mm²) | |
| 18-23 ft (5.5-7 m) | 10 AWG (5.26 mm²) | |
| 23-28 ft (7-8.5 m) | 10 AWG (5.26 mm²) | |
| 28-40 ft (8.5-12 m) | 8 AWG (8.37 mm²) | |
| 40A-50A Fuse | 0-13 ft (0-4 m) | 10 AWG (5.26 mm²) |
| 13-18 ft (4-5.5 m) | 10 AWG (5.26 mm²) | |
| 18-23 ft (5.5-7 m) | 8 AWG (8.37 mm²) | |
| 23-28 ft (7-8.5 m) | 8 AWG (8.37 mm²) | |
| 28-40 ft (8.5-12 m) | 6 AWG (13.30 mm²) | |
| 55A-80A Fuse | 0-13 ft (0-4 m) | 8 AWG (8.37 mm²) |
| 13-18 ft (4-5.5 m) | 6 AWG (13.30 mm²) | |
| 18-23 ft (5.5-7 m) | 6 AWG (13.30 mm²) | |
| 23-28 ft (7-8.5 m) | 4 AWG (21.15 mm²) | |
| 28-40 ft (8.5-12 m) | 3 AWG (26.67 mm²) | |
| 80A–100A Fuse | 0-13 ft (0-4 m) | 6 AWG (13.30 mm²) |
| 13-18 ft (4-5.5 m) | 6 AWG (13.30 mm²) | |
| 18-23 ft (5.5-7 m) | 4 AWG (21.15 mm²) | |
| 23-28 ft (7-8.5 m) | 3 AWG (26.67 mm²) | |
| 28-40 ft (8.5-12 m) | 2 AWG (33.62 mm²) | |
| 100A–140A Fuse | 0-13 ft (0-4 m) | 4 AWG (21.15 mm²) |
| 13-18 ft (4-5.5 m) | 3 AWG (26.67 mm²) | |
| 18-23 ft (5.5-7 m) | 2 AWG (33.62 mm²) | |
| 23-28 ft (7-8.5 m) | 1 AWG (42.41 mm²) | |
| 28-40 ft (8.5-12 m) | 1/0 AWG (53.49 mm²) | |
| 140A–160A Fuse | 0-13 ft (0-4 m) | 3 AWG (26.67 mm²) |
| 13-18 ft (4-5.5 m) | 2 AWG (33.62 mm²) | |
| 18-23 ft (5.5-7 m) | 1 AWG (42.41 mm²) | |
| 23-28 ft (7-8.5 m) | 1/0 AWG (53.49 mm²) | |
| 28-40 ft (8.5-12 m) | 2/0 AWG (67.43 mm²) | |
| 170A–190A Fuse | 0-13 ft (0-4 m) | 2 AWG (33.62 mm²) |
| 13-18 ft (4-5.5 m) | 2 AWG (33.62 mm²) | |
| 18-23 ft (5.5-7 m) | 1 AWG (42.41 mm²) | |
| 23-28 ft (7-8.5 m) | 1/0 AWG (53.49 mm²) | |
| 28-40 ft (8.5-12 m) | 2/0 AWG (67.43 mm²) | |
| 190A–220A Fuse | 0-13 ft (0-4 m) | 1 AWG (42.41 mm²) |
| 13-18 ft (4-5.5 m) | 1 AWG (42.41 mm²) | |
| 18-23 ft (5.5-7 m) | 1/0 AWG (53.49 mm²) | |
| 23-28 ft (7-8.5 m) | 2/0 AWG (67.43 mm²) | |
| 28-40 ft (8.5-12 m) | 3/0 AWG (85.01 mm²) | |
| 220A–260A Fuse | 0-13 ft (0-4 m) | 1/0 AWG (53.49 mm²) |
| 13-18 ft (4-5.5 m) | 2/0 AWG (67.43 mm²) | |
| 18-23 ft (5.5-7 m) | 2/0 AWG (67.43 mm²) | |
| 23-28 ft (7-8.5 m) | 3/0 AWG (85.01 mm²) | |
| 28-40 ft (8.5-12 m) | 4/0 AWG (107.22 mm²) | |
| 260A–300A Fuse | 0-13 ft (0-4 m) | 2/0 AWG (67.43 mm²) |
| 13-18 ft (4-5.5 m) | 3/0 AWG (85.01 mm²) | |
| 18-23 ft (5.5-7 m) | 3/0 AWG (85.01 mm²) | |
| 23-28 ft (7-8.5 m) | 4/0 AWG (107.22 mm²) | |
| 300A–350A Fuse | 0-13 ft (0-4 m) | 3/0 AWG (85.01 mm²) |
| 13-18 ft (4-5.5 m) | 4/0 AWG (107.22 mm²) | |
| 350A–400A Fuse | 0-13 ft (0-4 m) | 4/0 AWG (107.22 mm²) |
If the recommended cable size cannot be installed due to terminal size limitations, the minimum safe cable sizes listed below may be used under the following conditions:
- Use a larger cable whenever possible
- Cable length must remain below 13 ft (4 m)
- Regularly inspect the cable for overheating, as smaller cables experience higher temperature rise and greater voltage drop under full load current
| Fuse Current | Cable Size |
|---|---|
| 0–18 A | 18 AWG |
| 18–24 A | 16 AWG |
| 24–35 A | 14 AWG |
| 35–40 A | 12 AWG |
| 40–55 A | 10 AWG |
| 55–80 A | 8 AWG |
| 80–105 A | 6 AWG |
| 105–140 A | 4 AWG |
| 140–165 A | 3 AWG |
| 165–190 A | 2 AWG |
| 190–220 A | 1 AWG |
| 220–260 A | 1/0 AWG |
| 260–300 A | 2/0 AWG |
| 300–350 A | 3/0 AWG |
| 350–405 A | 4/0 AWG |
Compatible Renogy cables are available below:
- Battery to Charge Controller Tray Cables for 3/8 in Lugs
- Battery Inverter Cables for 3/8 in Lugs
- 1ft/2ft ANL Fuse Cable with Double Ring Terminals for 3/8 in Lugs
2.2 Device → Solar Panels
PV cables with MC4 waterproof connectors commonly available on the market are typically 12 AWG (4 mm²) or 10 AWG (6 mm²).
When the total current is ≤20 A, Y‑branch connectors may be used directly.
When total current exceeds 20 A, connect panels in parallel through a combiner box or busbar, then use a larger main output cable to connect to the power equipment.
Only weather‑resistant, UV‑resistant PV1‑F photovoltaic cables certified to local regulations shall be used.The minimum bending radius must be ≥ 43 mm (1.69 in).
The table below is based on copper‑core PV cables rated for 90°C (194°F), with DC voltage drop controlled within ≤3% and ambient temperature ≤40°C (104°F).
When ambient temperature >40°C(104°F), ampacity must be derated according to NEC 310.15(B). For example, 90°C-rated insulated cable at 40°C ambient temperature requires a correction factor of 0.91, equivalent to approximately 9% derating.
Additional derating of 15–25% is required when multiple cables are installed in conduit.
| Fuse Current | Cable Length | Recommended Cable Size |
|---|---|---|
| 0–10 A | 0–5 m (0–16.4 ft) | 12 AWG / 4 mm² |
| 10–20 A | 0–8 m (0–26.2 ft) | 10 AWG / 6 mm² |
| 20–30 A | 0–10 m (0–32.8 ft) | 8 AWG / 10 mm² |
| 30–40 A | 0–12 m (0–39.4 ft) | 6 AWG / 16 mm² |
| 40–50 A | 0–15 m (0–49.2 ft) | 4 AWG / 25 mm² |
| 50–60 A | 0–18 m (0–59.1 ft) | 3 AWG / 30 mm² |
| 60–70 A | 0–20 m (0–65.6 ft) | 2 AWG / 35 mm² |
| 70–80 A | 0–25 m (0–82.0 ft) | 1 AWG / 42 mm² |
| 80–90 A | 0–30 m (0–98.4 ft) | 1/0 AWG / 50 mm² |
| 90–100 A | 0–35 m (0–114.8 ft) | 2/0 AWG / 70 mm² |
| 100–150 A | 0–40 m (0–131.2 ft) | 4/0 AWG / 120 mm² |
This table provides general recommendations only. Final cable selection should be verified based on actual system voltage, cable length, and allowable voltage drop. For precise calculations, refer to NEC 310.16 ampacity tables (United States) or CSA C22.1 Tables 2/4/5 (Canada).
Renogy offers compatible solar extension cables:
- Solar Panel Extension Cable with Male to Female Solar Connectors (Single)
- Solar Panel to Charge Controller Adaptor Kit
3. Recommended Terminal Sizes
The terminal sizes listed below are general recommendations. Refer to the applicable product user manual for the exact required terminal specifications.
| Equipment Terminal | Recommended Cable Lug Size |
|---|---|
| M6 | M8 Terminal / 5/16 in Lug |
| M8 | M10 Terminal / 3/8 in Lug |
| M10 | M12 Terminal / 1/2 in Lug |
