Quick reference tables you can keep on hand — wire sizing, peak sun hours, system voltage, and battery depth of discharge. Print them or save as a PDF for the workshop or the roof.
Approximate current a copper conductor can carry. Always confirm against your local electrical code, the cable's insulation rating, and derating for temperature and grouping.
| Cross-section (mm²) | AWG (approx) | Approx. ampacity (copper) |
|---|---|---|
| 1.5 mm² | 16 AWG | ~15 A |
| 2.5 mm² | 14 AWG | ~20 A |
| 4 mm² | 12 AWG | ~28 A |
| 6 mm² | 10 AWG | ~36 A |
| 10 mm² | 8 AWG | ~50 A |
| 16 mm² | 6 AWG | ~68 A |
| 25 mm² | 4 AWG | ~90 A |
| 35 mm² | 2 AWG | ~110 A |
Size a cable for your run: Cable size calculator · Voltage drop calculator
Rough annual-average peak sun hours (equal to daily kWh/m²). Use as a starting estimate; check local data for a real design.
| Region | Typical peak sun hours (annual avg) |
|---|---|
| Northern Europe, UK, Scandinavia | 2 – 3 |
| Central Europe, northern US, southern Canada | 3 – 4 |
| Humid tropics | 4 – 5 |
| Mediterranean, southern Europe, most of Australia, southern US | 4.5 – 5.5 |
| Deserts: Jordan, the Gulf, Sahara, US Southwest | 5.5 – 6.5 |
Learn more: Peak sun hours explained · Energy production calculator
Higher system voltage means lower current for the same power — thinner cables and less voltage drop. Bigger systems use higher voltage.
| Battery voltage | Typical system size | Best for |
|---|---|---|
| 12 V | Up to ~1–1.5 kW | RVs, boats, sheds, small setups, short runs |
| 24 V | ~1.5–3 kW | Medium off-grid homes and cabins |
| 48 V | Above ~3 kW | Larger homes and off-grid; most modern battery systems |
Related: Battery Ah to kWh converter · Cable size calculator
How deep you can safely discharge each battery type, and roughly how many cycles it lasts. Staying within the recommended DoD extends battery life.
| Battery type | Recommended DoD | Typical cycle life |
|---|---|---|
| Lead-acid (flooded) | ~50% | 500 – 1,000 cycles |
| Lead-acid (AGM / gel) | ~50–60% | 600 – 1,200 cycles |
| Lithium (LiFePO4) | ~80–90% | 3,000 – 6,000+ cycles |
Related: Battery calculator · Lithium vs lead-acid