About SolarBatterySizing.com
An open-access electrical engineering suite built to provide homeowners, RV builders, marine electricians, and off-grid DIYers with mathematically rigorous, unbiased sizing tools.
Why We Built This: Eliminating Sales Bias
Most online solar and battery calculators are commercial sales funnels operated by retail equipment distributors or affiliate blogs. Their formulas are frequently distorted in two directions:
Inflating inverter surge wattages and recommended battery capacities to push buyers into purchasing larger, high-margin retail kits they do not need.
Ignoring inverter conversion losses, voltage drop over low-voltage DC cables, and Depth of Discharge (DoD) electrochemical limits—leading to tripped inverters, dead battery banks, and fire risks.
SolarBatterySizing.com was created by Gourav to solve this problem. Our calculation engines are completely non-commercial, unbiased, and independent. We sell no hardware, take no equipment sponsorships, and display objective engineering truth derived directly from established electrical standards.
Our Engineering Calculation Doctrine
Every tool across our suite adheres strictly to recognized international electrical engineering codes:
3% Voltage Drop & 125% Overcurrent
All wire gauges are sized using exact copper Circular Mils formulas (CM = (2 × K × I × L) / V_drop with K = 12.9 Ω·cmil/ft) to guarantee maximum 3% voltage drop per NEC recommendations, paired with 125% continuous overcurrent protection sizing.
Metric Conductors (mm²)
For international and marine installations, metric wire cross-sections (S = (2 × ρ × L × I) / V_drop) are calculated using 75°C operating resistivity (ρ = 0.0215 Ω·mm²/m) and validated against standard European conductor cross-sections.
Chemistry-Specific Usable Capacity
Calculations enforce chemistry protection: 85% usable capacity for Lithium Iron Phosphate (LiFePO4) and 50% for Lead-Acid (AGM/Gel) to safeguard against rapid cell degradation, cycle loss, and premature battery death.
Dynamic Discharge Derating
Our Battery Run Time engine compensates for non-linear high-amp draw on lead-acid batteries (Ik × t = C, with k = 1.15 for AGM and 1.25 for Flooded), preventing sudden unexpected power cutoffs under heavy appliance loads.
Automated Testing & Mathematical Verification
Code quality and calculation precision are not taken on faith. Every mathematical engine on SolarBatterySizing.com is covered by automated unit test suites running in CI on every code deployment:
Creator Transparency & Contact
SolarBatterySizing.com is designed, built, and maintained independently by Gourav. If you spot a calculation discrepancy, have a question regarding specific electrical code interpretations, or want to suggest new electrical tools, you can reach out directly.
Explore Our Engineering Sizing Tools
Ensure your entire off-grid power architecture is safe and properly balanced using our companion engineering calculators.
Master Solar & Battery Sizer→
Complete off-grid system sizing: appliances to battery bank, inverter, and solar array.
Battery Run Time Calculator→
Calculate operating hours and days for 12V, 24V, or 48V batteries under continuous loads.
Solar Charge Time Calculator→
Determine peak sun hours and days required to charge batteries with solar panels.
Solar Panel Sizer & Output→
Calculate total solar array kW, panel count, and roof area needed for daily energy needs.
Solar Wire Gauge & Fuse Sizer→
NEC 3% voltage drop AWG and IEC mm² cable sizing with fuse rating recommendations.
Watts to Amps Calculator→
Instant 2-way DC & AC single-phase converter with wire gauge and fuse recommendations.
Ah to kWh Battery Converter→
Convert Amp-Hours to kWh and Wh across 12V, 24V, and 48V battery systems with DoD.