🔆 Solar Recharge Reality Check Calculator

Estimate how much energy your solar panel can realistically add per day, how long it takes to refill a battery, and whether you’re actually gaining energy once you account for real-world losses (and optional loads).

Inputs

Solar panel watts
Common: 100W, 200W, 400W

“Good sun” hours per day
Typical: 2–6 (winter lower)

Losses / derate
Covers clouds, angle, heat, MPPT, cable loss

Power station solar input cap (W)
If unknown, leave 9999

Battery size (Wh)
Example: 256Wh, 512Wh, 1024Wh

Starting battery %
How full it is when charging begins

Optional continuous load (W)
Example: Wi-Fi 10W, fridge average 60–120W

Notes: “Good sun hours” is not daylight hours. It’s the equivalent time your panel would average near its rated output. This is why winter + clouds can turn “solar recharge” into “solar trickle.”

Want this to be extra honest? Use 2–3 sun hours and 40% losses for stormy/winter outage conditions.