Solar Window: Solar Forecast

Billin

About this app

Solar Window tells you how much electricity YOUR solar panels will make over the next 7 days, hour by hour, and when to run the dishwasher, washing machine, water heater or EV charger to use your own sunshine.

Most "solar forecast" apps show irradiance in kWh/m² and leave the maths to you. Solar Window runs a full photovoltaic model for your roof (size, direction, tilt, inverter and losses) and gives you the number that matters: kWh from your system.

☀️ YOUR 7-DAY SOLAR FORECAST
• Daily kWh for your system, with an Excellent / Good / Fair / Poor rating against that day's clear-sky potential
• Hourly power chart: drag across it to see each hour, with clear-sky potential behind it
• "Still to come today": how much generation is left from now until sunset
• Sunrise, sunset, daytime cloud cover, UV and how high the sun climbs
• Weather risks for panels: thunderstorms, hail, snow, ice, gales and heat

⚡ BEST TIME TO RUN APPLIANCES
• The best 2-hour solar window every day
• Planner for dishwasher, washing machine, water heater and EV charging, with editable power and run time
• Add your household base load to estimate solar coverage and grid energy
• Save plans and add them to your calendar with a reminder

🔔 ALERTS
• Morning summary with today's kWh and best window
• Evening alert when tomorrow will be below or above your threshold, in time to decide on overnight battery charging

🏠 BUILT FOR REAL ROOFS
• Up to 3 roof faces (for example east + west) sharing one inverter
• Inverter clipping when you know its AC rating
• Works worldwide: search any town or use your location
• Record actual generation and compare it with the forecast saved before the day began

🔒 PRIVATE AND FREE
• No ads, no account, no inverter login
• Your settings stay on your phone. Only your approximate coordinates are sent to the weather service.
• Dark mode and 11 languages

HOW IT WORKS
Weather from Open-Meteo (global and diffuse radiation, temperature, wind) feeds a model ported from pvlib, the open-source PV library used by researchers: NREL solar position, Perez transposition, reflection losses, SAPM cell temperature, PVWatts DC and inverter models, and Ineichen clear-sky. Every figure is an estimate from a weather forecast, not a guarantee.

Weather data by Open-Meteo.com (CC BY 4.0).

What’s new

Global launch with 13 languages, enhanced solar forecasting model, and UI improvements.