Free tool
MPPT Sizing · Array Configuration · ROI vs Generator
Three precision tools in one. Size your MPPT charge controller correctly using absorption voltage (not nominal), find every valid panel array configuration for your specific MPPT, and calculate exactly how fast your solar system pays back against a generator — with real Nigerian fuel price escalation built in.
How to use this calculator
Tool 01
MPPT sizing
Enter your total array wattage, battery voltage, and panel datasheet specs. Get the minimum MPPT current rating and safe Voc tier — with temperature-corrected worst-case voltage.
Tool 02
Array configurator
Enter your panel count, datasheet values, and MPPT limits. Every valid series/parallel combination is evaluated and the best configuration highlighted automatically.
Tool 03
ROI vs generator
Enter your system cost, generator running costs, and fuel escalation rate. Get payback period, 10-year savings, and a year-by-year cumulative savings breakdown — all in Naira.
Solar & MPPT Calculator
MPPT Sizing · Array Config · ROI vs Generator
Eneronix
Your Energy, Our Precision
1 MPPT Sizing
2 Array Config
3 ROI / Payback
I_MPPT ≥ P_array / V_charge × 1.25 · V_charge = absorption voltage (14.4 / 28.8 / 57.6V)
Voc_array = Voc_panel × N_series × (1 + α/100 × (T_min − 25)) · α negative for silicon
Voc_max_needed = Voc_array × 1.20 · 20% safety margin (Victron / industry standard)
Voc_array = Voc_panel × N_series × (1 + α/100 × (T_min − 25)) · α negative for silicon
Voc_max_needed = Voc_array × 1.20 · 20% safety margin (Victron / industry standard)
15°C
Engineering estimates only. MPPT sizing results are design minimums — always round up to the next standard commercial rating. Array voltage calculations assume STC conditions; real Voc varies with temperature and irradiance. ROI projections are based on user inputs and do not account for battery replacement cycles, currency fluctuation, or changes in fuel subsidy policy. Verify all designs with a qualified solar engineer. © Eneronix — eneronix.com
Eneronix
Your Energy, Our Precision
Understanding your results
Why absorption voltage, not nominal?
MPPT output current is calculated at the actual charging voltage (14.4/28.8/57.6V), not nominal (12/24/48V). Using nominal underestimates current by up to 20%, which could undersize your controller and cause overheating.
Voc rises when it’s cold
Silicon panels have a negative temperature coefficient — the colder the panel, the higher the open-circuit voltage. The 20% safety margin on top of this cold-temperature Voc is the industry standard to prevent overvoltage damage to the MPPT.
Why does Vmp need headroom?
The MPPT can only push current into a battery when the array’s operating voltage (Vmp) is above the battery’s charging voltage. A minimum of 5V headroom is required — below this, the controller stalls and no charging occurs.
ROI with fuel escalation
Nigerian fuel prices have historically risen 10–25% per year. The escalation slider compounds this annually — making each year’s generator cost higher and the solar payback shorter. A conservative 10% gives a realistic baseline.