SolarWattPro is a free resource for anyone sizing a solar power system, whether it is a 100-watt panel on a camper van, a battery backup for power outages, or a fully off-grid home. Our solar, battery and inverter calculator turns your daily energy use into a complete system blueprint in seconds, and our sizing guides explain the math behind every number.
Who runs this site
Yasir Hafeez
Founder & Editor, SolarWattPro
Email: secure.accesshub@gmail.com
Yasir Hafeez is the founder and editor of SolarWattPro. He writes straightforward, actionable guides on home and business solar, battery storage and backup power, and builds the site's free calculators, so readers can plan the right system with confidence and move towards true energy independence.
Why we built SolarWattPro
Sizing a solar system usually means sorting through sales pitches, forum arguments and spec sheets written for engineers. Most mistakes, such as batteries that die by midnight, inverters that trip on a refrigerator start-up surge or charge controllers that burn out on a cold morning, come from a handful of simple calculations done wrong. We wanted one place where those calculations are done correctly and shown in plain language.
How our calculations work
- Solar array size = daily watt-hours ÷ (peak sun hours × 0.80), allowing 20% for heat, dust, wiring and inverter losses.
- Battery capacity = (daily watt-hours × days of autonomy) ÷ (battery voltage × depth of discharge), using 85% for LiFePO4 and 50% for lead-acid.
- Charge controller current = (array watts ÷ battery voltage) × 1.25 safety margin.
Every article shows its formulas and worked examples so you can check the numbers yourself. You can read more about how we research and update articles in our Editorial Policy.
Important safety note
Our calculators and guides are for planning and education. Electrical installations involve real hazards and local code requirements, so always have your final design and installation checked by a qualified, licensed electrician.
Get in touch
Questions, corrections or suggestions for a new guide are always welcome. Email secure.accesshub@gmail.com or visit our contact page.