MVP calculator for daily energy use, battery sizing, solar sizing, MPPT sizing, DC cable sizing (voltage drop), fuse suggestions, and a simple shopping-list export.
Tip: For lead-acid builds, pick 50% DoD. For lithium, 80% is a good default.
Loads
Add appliances and the calculator totals Wh/day and Ah/day.
Appliance
Watts
Hours/day
Qty
Wh/day
Total
0
Notes: For compressor fridges, use an average (e.g. 30–60W) or measure with a plug-in meter.
Solar assumptions
This uses “effective sun hours” and a system efficiency factor.
In UK summer, 3–5 hours is common. In UK winter, 0.5–1.5 can be more realistic depending on setup.
Results
Daily energy
0 Wh/day
≈ 0 Ah/day @ 12V
Battery recommendation
0 Ah
for 2 days, DoD 80%, incl. reserve
Solar recommendation
0 W
based on sun hours & efficiency
Inverter suggestion (rule of thumb)
0 W
= peak load × 1.25 (if you use AC loads)
Solar panel + MPPT sizing (Victron-style)
Enter panel specs and wiring. The calculator recommends the smallest common MPPT model that meets voltage + current headroom.
MPPT selection logic:
PV max voltage ≥ Voc_string × coldFactor and
MPPT output current ≥ (PV watts ÷ battery volts) × chargeFactor.
Always confirm with the panel datasheet and MPPT manual.
DC Cable & Fuse Quick Sizer
Voltage-drop sizing using copper resistivity. Good for 12V/24V DC circuits (lights, fridge, DC-DC, inverter DC feed, etc.).
Cable sizing formula: A(mm²) = (2 × L × I × 0.0175) / Vdrop(V). This is voltage-drop based, not thermal. Always check the cable's current rating, installation method, and the device manual.
Shopping list output (copy / CSV)
Enter a couple of key cable lengths and the tool generates a simple parts list you can copy into a quote or spreadsheet.
Tip: paste into Excel or your quoting template. The CSV uses Quantity, Item, Notes.