About VoltCalcs
What This Site Does
VoltCalcs provides free, browser-based calculators for battery sizing, solar system design, and electrical engineering. Every calculator runs instantly in your browser with zero API calls, no account walls, and no paywalls.
The site serves DIYers, off-grid enthusiasts, RV owners, marine users, solar installers, and electricians who need quick, accurate answers to power and energy questions. Unlike general-purpose calculator farms that spread thin across thousands of topics, VoltCalcs goes deep on battery, solar, and electrical with real educational content.
Who Built This
Dan Dadovic — Commercial Director at Ezoic Inc. & PhD Candidate in Information Sciences
Dan is a PhD candidate in Information Sciences (in progress, EQF 8) at the Faculty of Organization and Informatics (FOI), University of Zagreb. He holds a Master's in Informatics and a Master's in Economics from FOI Zagreb (both EQF 7), and a Bachelor's in Informatics (EQF 6). He works professionally as Commercial Director at Ezoic Inc., leading revenue strategy across digital publishing. On the energy side, Dan has hands-on experience with residential solar panel installation, DIY battery bank construction, off-grid power systems, wind power, and EV ownership/driving — all from building, maintaining, and operating his own systems.
The practical experience that shapes the calculators on this site comes from years of hands-on builds: a residential rooftop solar array (string inverter, grid-tied), a DIY 12V LiFePO4 battery bank built from prismatic cells with an active BMS, a small-wind setup that taught him more about grid-tie inverters and dump loads than any spec sheet ever would, and the everyday electrical work that comes with maintaining a household — sub-panel additions, voltage-drop troubleshooting, and the occasional “why is the breaker tripping” detective job. Every calculator on this site was built because Dan needed the answer himself, then realized the closest tool online either cost money, walled it behind a sign-up, or skipped the variable that mattered most.
Dan is not a licensed electrician or certified solar installer. The calculators on this site are practical estimation tools built from hands-on experience and standard electrical formulas — not professional engineering software. For critical electrical work, always consult a licensed electrician. Read the full disclaimer and editorial policy.
Independence
VoltCalcs is independently owned and operated. It is not affiliated with any battery manufacturer, solar company, or electrical equipment brand. Calculator results are unbiased — the site does not push any particular product or brand.
How the calculators are built
Every formula on this site cites a verifiable source. Electrical calculators draw from the National Electrical Code (NEC 2023) for US-aligned math, IEC 60364 where international standards apply, IEEE technical papers for motor and transformer behaviour, and the fundamental laws — Ohm's, Kirchhoff's, Faraday's — for everything else. Battery and solar calculators use manufacturer-published discharge curves, the Peukert equation for high-current draw, and ASHRAE solar irradiance data when location matters. Where a real-world result has known uncertainty, the output is shown as a range, not a single number — discharge runtime, panel output across seasonal weather, and inverter efficiency all sit in this category. Estimates are estimates. The site never claims a calculator output is the exact value you'll measure on a meter, and never recommends a specific brand or product for the result.
Get in Touch
Found a bug? Have a feature request? Want to suggest a new calculator? Send us feedback. Every message gets read.