OnSun Residential Solar Forcasting Mobile App by Vireo Energy
See Your Solar Before It Happens
OnSun is Vireo Energy's consumer app for households with rooftop solar. It forecasts a home's solar production up to 7 days ahead and recommends the best times to run appliances, so families use more of their own generation instead of exporting it for a few cents and buying it back at full retail price.
At its core, OnSun combines professional weather-model data, and a physics-based models of the panels themselves, resolved at 15-minute to 1-hour intervals depending on region. The app turns that into recommendations to maximise solar usage with reminders.
OnSun deliberately requires no complicated setup: no hardware, no smart plugs, no inverter or meter integration. It never switches an appliance on or off; it tells the household when, and they press start. Savings figures are always presented as estimates. That zero-install design means any grid-connected solar home in the world can use OnSun.
OnSun models nine common appliance types plus custom loads, and is localised into more than a dozen languages.
Available today on the App Store and Google Play
With OnSun, a solar household can:
✔ See production for the week ahead, hour by hour
✔ Run appliances inside the day's solar window
✔ Lift self-consumption from a typical 25-35% toward 60-80%
✔ Track estimated savings and solar used over time
✔ Start free, with an optional Pro subscription
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THE CASE FOR SELF-CONSUMPTION And The NEED
Feed-in tariffs are falling everywhere solar succeeds. In Australia, exports typically earn 4-8 cents per kilowatt-hour (some retailers now pay 1-2 cents) while grid power costs 25-40 cents to buy back. California's move to net billing cut export credits to a fraction of retail, and UK Smart Export Guarantee rates sit well below retail prices. The pattern is structural: midday solar floods the market, the belly of the duck curve, so the value keeps shifting to using generation onsite.
Yet a typical solar home still exports 50-70% of what it generates, then buys electricity back in the evening. Closing that gap is worth several hundred dollars a year per household and needs no new hardware, only better timing. Rooftop solar is mainstream: about one in three Australian homes has it, with tens of millions more systems across the US and Europe. That timing gap is the product surface OnSun addresses. See more information on benifits here.
The catch is that the solar window is not a fixed time of day. It moves with cloud cover, season and the direction the roof faces: a clear summer day might give five strong hours, a grey winter morning ninety useful minutes, and an east-facing roof peaks well before a west-facing one. A standing rule like "run it at midday" quietly fails on exactly the days it matters most. This is why forecasting sits at the centre of OnSun. It predicts each roof's output hour by hour for the days ahead, so a household can place the washing, the pool pump or an EV charge into the hours that will actually deliver, and hold a big load for a sunnier day when the forecast says tomorrow is not worth it. Knowing on Monday that Thursday is the week's best solar day is what turns good intentions into a plan. The full breakdown is in OnSun's Solar Savings Guide.
