LiFePO4 Solar FAQ

A typical camper van uses 1000–2000 Wh/day. A 12V 100Ah LiFePO4 stores 1200 Wh, of which 90% is usable = 1080 Wh per battery. Formula: (daily Wh × autonomy days) ÷ 1080. Example: 1500 Wh/day × 2 days = 3000 Wh ÷ 1080 = 3 batteries minimum.

12V — under 500 Wh/day. 24V — 500–2000 Wh/day. 48V — above 2000 Wh/day. Higher voltage = lower current = thinner cables, less heat, lower cost. A 1000W inverter at 12V draws ~83A; at 24V only ~42A.

Formula: Wp = net daily Wh ÷ peak sun hours ÷ 0.78. The 0.78 factor accounts for MPPT efficiency, wiring losses, and charge/discharge losses. Example: 1000 Wh ÷ 3.5h ÷ 0.78 = 367 Wp for year-round NL use.

Cable sizing depends on current (A), run length (m), and maximum voltage drop (%). Example: 12V, 1000W inverter (~83A), 1m run, 3% max drop → minimum 16mm². Same with 3m → 35mm². SOLARIS calculates every segment automatically.

Key specs: ✓ 4000+ guaranteed cycles at 80% DoD, ✓ BMS current exceeding 1.5× inverter peak, ✓ Self-heating if charging below 0°C, ✓ 5–10 year warranty. Top EU brands: LiTime, Power Queen, Redodo, Timeusb. For the US: SOK Battery, LiTime.

DoD is the percentage of capacity used per cycle. LiFePO4 handles 100% DoD technically, but 90% is recommended. At 90% DoD, quality LiFePO4 lasts 4000+ cycles — roughly 10 years of daily cycling.

W/kW = power (instant). Wh/kWh = energy (power × time). A 45W fridge running 24h = 1080 Wh. Ah without voltage is meaningless — always compare batteries in Wh.

Fit score (0–100) rates match quality. Deductions: −30 wrong voltage, −40 insufficient capacity, −10 oversized, −50 BMS too low. Score above 70 = Best Match.

Autonomy days = consecutive days without solar. Camper: 1–2 days, Off-grid cabin: 3–5 days, Home backup: 1–2 days. More days = more batteries = higher cost.

DIY — custom battery bank with MPPT, inverter, BMS, cables. Lower cost/Wh. All-in-One — portable power stations (EcoFlow, Jackery, Bluetti). Plug-and-play, zero wiring, higher cost/Wh.

PVGIS is a free EU satellite database for solar yield. Use it for fixed installations with unusual shading/elevation. For mobile use (camper, boat), the regional profile is usually sufficient.

Batteries, MPPT controller, inverter, DC cables (mm² per segment), fuses (ANL/MIDI/Mini), and regional installation standards. Each item has affiliate buy links and coupon codes where available.

Series wiring adds voltage (e.g. 2× 18V = 36V) while current stays the same. Parallel wiring adds current while voltage stays the same. Series is preferred for long cable runs because higher voltage means lower current and less voltage drop. Use series when your MPPT can handle the combined Voc, and parallel when you need to stay below the MPPT input voltage limit. SOLARIS generates an interactive wiring diagram showing your exact S/P configuration.

Size your inverter based on peak load, not average consumption. Add up all appliances that may run simultaneously. A 1500W coffee maker + 100W fridge + 50W lights = 1650W peak. Choose an inverter rated at least 20% above peak → 2000W minimum. Must be pure sine wave for sensitive electronics. SOLARIS sizes the inverter automatically from your appliance table.

Formula: Battery Wh = daily consumption (Wh) × autonomy days ÷ DoD. Example: 1200 Wh/day, 2 autonomy days, 90% DoD = 1200 × 2 ÷ 0.9 = 2667 Wh minimum. Convert to Ah: 2667 ÷ system voltage. At 12V = 222 Ah, at 24V = 111 Ah. The SOLARIS calculator does this automatically and matches compatible LiFePO4 batteries.

The MPPT must support a LiFePO4 charge profile (14.2–14.6V absorption for 12V systems). Size by: Voc of your solar array (must be below MPPT max input voltage) and charge current (solar Wp ÷ battery voltage). Example: 400W panels on a 12V bank = ~33A charge → choose a 40A MPPT. Victron SmartSolar and EPEver Tracer are popular LiFePO4-compatible options.

Basic wiring order: Solar panels → MC4 cables → MPPT input terminals → MPPT battery terminals → fuse → battery bank. Always connect the battery to the MPPT first, then connect solar panels. Use appropriately sized cables: minimum 4mm² for solar-to-MPPT runs (industry standard for outdoor wiring). SOLARIS generates a complete wiring diagram with cable sizes for every segment.

A solar wiring diagram shows how all components connect: panels, MPPT charge controller, battery bank (series/parallel configuration), inverter, fuses, and cables. You need one to ensure correct polarity, proper cable sizing per segment, correct fuse ratings, and safe installation. SOLARIS generates an interactive wiring diagram based on your specific system — including drag-and-drop component layout and a cable sizing table.

Yes. Wire them in series (+ to −) to double voltage, or in parallel (+ to +, − to −) to double current. Both go through an MPPT controller before the battery. Series is generally preferred: higher voltage = less current = thinner cables and less loss. Check that combined Voc stays below your MPPT maximum input voltage.

12V for small systems under 500 Wh/day (single battery, camper). 24V for medium systems 500–2000 Wh/day (off-grid cabin, larger camper). 48V for large systems above 2000 Wh/day (whole-home off-grid, commercial). Higher voltage means less current, thinner cables, and more efficient inverters. SOLARIS recommends a voltage based on your consumption.

Seven steps: 1. Calculate daily energy consumption in Wh. 2. Choose system voltage (12V/24V/48V). 3. Size solar panels based on location and consumption. 4. Size battery bank for autonomy days. 5. Pick an MPPT charge controller. 6. Pick a pure sine wave inverter. 7. Size cables and fuses per segment. SOLARIS walks you through all seven steps and generates a complete bill of materials with buy links.

Depends on three factors: daily consumption (Wh), peak sun hours at your location, and panel wattage. Formula: panels needed = daily Wh ÷ (peak sun hours × panel Wp × 0.78). Example: 3000 Wh/day, 4 peak sun hours, 400W panels = 3000 ÷ (4 × 400 × 0.78) = 2.4 → 3 panels. Use the SOLARIS calculator with your exact location for NASA satellite data.