Rooftop Solar Forecaster

Use more of your own solar generation!

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Hi All, 👋 I'm Steve. I've worked in energy engineering for most of my career, and I put panels on my own roof expecting the bill to fall off a cliff. It didn't. The panels were fine. My timing was terrible. All the power arrived while the house was empty, went out to the grid for a few cents, and came back at full price. My solar app showed me production yesterday. Beautiful charts of a decision I could no longer make. So we built the opposite: a forecast. WHAT ONSUN DOES You tell it where you are, how big your array is, and which way the roof faces. There's no inverter login, no smart plug, no hardware, and it works with any grid-connected system because it models production rather than reading it off your equipment. From there: • A 7-day forecast of your own roof, hour by hour, with a production curve, a "now" marker and a confidence band. • A daily solar summary: day quality, percentage of your system's potential, and when peak sun lands. • Appliance scheduling. Pick a day, drop your appliances onto the solar curve, and see each one's start time, how much of its run is covered by sun, and what it saves. • Reminders. A notification when the window opens, plus a countdown, because the whole thing falls apart if you forget to press start. • Weekly insights: solar used per day, savings per day, your best day, and a 7-day outlook that flags the sunniest day coming ("Sunday is your sunniest day"). • Long-term insights: total savings since you started, solar used by appliances, run counts, a top-appliances table, and produced-vs-used over 7 days to all time. • Rainfall on the forecast chart too, for the people who dry the washing on a line rather than in a dryer. • A performance setting, so you can compare the forecast against what your system actually did and tune it. WHAT'S NEW IN 2.0 We launched here a while ago. This version is a rebuild, not a repaint. • Full redesign, top to bottom. Three swipeable tabs: Forecast, Schedule, Insights. • Confidence bands on the forecast. Weather is a probability, so the chart now shows the likely best and worst case instead of pretending it knows. • Proper appliance load profiles. A dishwasher isn't a flat block of power for two and a half hours, it's a heating spike and a long quiet tail. Nine appliance models now follow the real shape of a run, including an SOC-aware EV charging curve, thermal modelling for air conditioning, and duty cycles for pool pumps. • Long-term insights, so you can see whether any of this is actually working over months rather than days. • More frequent forecast refreshes. • Localised into 40 languages, which was its own small adventure. • A long tail of fixes. FREE AND PRO Free gives you a shorter forecast and less appliances, and but completely usable for Free. Pro unlocks the full week, unlimited appliances and more frequent updates. iOS and Android are both live today. One honest caveat: savings are modelled from the forecast and the appliance profiles, not metered. OnSun is a planning tool, not a meter, and it never switches anything on for you. You press start. I'd love to hear how the forecast holds up against your real production, especially outside Australia where the weather models and roof angles are different.