A single day, hour by hour
- Pick a day. The model of my roof shows where the sun was through it and what the neighbor's tree shaded.
- The chart under it shows where each hour's electricity came from.
- The two move together. The chart marks the hour the model shows, and a click on an hour in the chart moves the sun into it.
- The Sun Position page says how the model is built and what in it is approximate.
the sun and its path that day
a face the sun is behind
a panel in the tree's
shade
the model's hour, in the
chart below
- The model steps through the day 10 minutes at a time, as the Sun Position page does, and the chart below marks the hour that holds the step.
- The readout gives what my array made in that 10-minute window.
- The chart's solar bar for the hour reads the same record by the same rule, over the whole hour.
- A reading holds across a quiet spell while the recorder runs, and an hour with any part not recorded is left out, as a window is.
Hour by hour
—
- The chart shows where each hour's electricity came from, and where the surplus went.
- Bars above the line supply my house. Bars below it leave: sold to the grid or put into the batteries.
- The three sources sum to household demand: the meters satisfy solar + grid + battery = load. That is not a choice of model.
- Over the — instants when all four were written in the same second, the median disagreement was — kW and the 99th percentile — kW.
- So the bars above the line, less the bars below it, are the load, with nothing rounded. Solar sent to the grid or batteries is not household use.
- A clear summer day has a wide blue middle over a teal trough as the batteries fill, then a teal evening as they empty. A winter day is mostly magenta.
- On — the house used — kWh and drew — kWh from the grid: —% of the day's use.
- That share can pass 100%, on a day the grid also charged the batteries.
- The buttons jump to days the record picks, not days I chose: daylight picks the longest and shortest, the weather station the hottest and coldest, the meters the rest.
solar battery grid above the line supplies, below it leaves