Solar Day Forecast by Why Solar

Approximate daily solar timing for your Australian locality, from forecast cloud cover and sun position. Not a generation forecast.

Solar Day Forecast is a small Chrome extension from Why Solar. It suggests the part of today when the skies look clearer and the sun sits higher for the Australian locality you choose. It's an approximate guide based on forecast cloud cover and sun position. It suggests an approximate time to use appliances, based on forecast cloud and sun height. It only includes hours when the sun is at least 15 degrees above the horizon. It doesn't see your roof and doesn't predict how much power your panels will produce. HOW IT WORKS Enter an Australian postcode, then choose your locality from the places that may match it. Each morning the extension checks the forecast while Chrome is running. The toolbar badge gives you a quick read. The popup shows today's suggested window in local time, the locality it's for and when it was last updated. The popup can also show an hourly graph for the day. Each bar is a relative guide based on forecast cloud cover and sun height, not a measure of solar output. It shows today's appliance-timing suggestion before sunrise and during daylight, then tomorrow's after the day's last daylight, when suitable forecast data is available. You can change your postcode or locality, or reset, at any time. Morning notifications are optional and stay off unless you turn them on. They can only arrive while Chrome is running and your device is awake. HOW LOCATIONS WORK The forecast uses a representative point for the suburb or locality you choose, not your roof or address. Why Solar derives that point inside the ABS 2021 Suburbs and Localities boundary. Before a forecast request, the point is truncated and may be adjusted to a neighbouring forecast grid cell, so the location used for weather can sit slightly away from it. Postcode matches are approximate. They come from ABS 2021 Postal Areas, which aren't a current delivery postcode directory. Some postcodes may not be found, such as PO box only postcodes or postcodes changed since 2021. For large localities, the point may not land near the town centre. WHAT IT CAN'T TELL YOU The extension doesn't know which way your panels face, your shading, your system size, your household use or your electricity plan. It doesn't predict your solar output, your bill or what your system can supply. On cloudy days it suggests you check your electricity plan before shifting appliance use, because the weather can't tell you what your plan charges. If the forecast is out of date or there isn't enough usable data to suggest a time to use appliances, the extension tells you; a partial forecast can still show a suggestion when enough usable data remains, with missing hours marked as unknown in the graph. PERMISSIONS Storage: remembers your postcode, locality, settings and latest forecast in Chrome. Alarms: schedules the morning check. Notifications (optional): Chrome asks you only if you turn notifications on. FORECAST REQUESTS To get a forecast, the extension sends the approximate coordinates for the locality you choose to a Why Solar forecast service hosted on Cloudflare, using an ordinary web request. No special Chrome host permission is requested for this web request. That service requests the forecast from MET Norway. As with any web request, Why Solar and Cloudflare receive your IP address with it. The popup has a small "Get solar quotes" link that opens Why Solar's website. DATA SOURCES Based on data from MET Norway, licensed under CC BY 4.0. Timing guidance calculated by Why Solar from cloud cover and sun position. Not a solar generation forecast. MET Norway source: https://api.met.no/weatherapi/locationforecast/2.0/documentation Licence: https://creativecommons.org/licenses/by/4.0/ Locality data: Australian Bureau of Statistics, Australian Statistical Geography Standard (ASGS) Edition 3, 2021: Suburbs and Localities and Postal Areas, © Commonwealth of Australia, licensed under CC BY 4.0. Why Solar has modified this data to derive representative locality points and approximate postcode matches. Use of ABS data does not imply ABS endorsement. ABS digital boundary files: https://www.abs.gov.au/statistics/standards/australian-statistical-geography-standard-asgs/edition-3-july-2021-june-2026/access-and-downloads/digital-boundary-files ABS copyright: https://www.abs.gov.au/website-privacy-copyright-and-disclaimer Licence: https://creativecommons.org/licenses/by/4.0/