Solar Calculators
Free, no-signup tools for designing DIY and off-grid solar systems. Every calculator runs in your browser.
Solar Panel Angle Calculator
Find the optimal tilt angle for your location, plus seasonal and month-by-month settings.
Open calculator →Solar Wire Size Calculator
Get the right wire gauge (AWG & mm²) from voltage, current, cable length and voltage drop.
Open calculator →Solar Charge Controller Calculator
Size your MPPT or PWM controller from array watts and battery voltage, with a safety margin.
Open calculator →Built for DIY and off-grid solar
SolarSizr focuses on the calculations that come up when you build your own solar system, whether that is on a van, an RV, a boat, a cabin or a backyard shed. Instead of pushing you toward a paid installation, each tool gives you a clear, transparent number and shows the formula behind it.
New calculators are added over time. If there is one you would like to see, let us know on the contact page.