Below is a graph of the recent output of the solar testbed from the Victron VRM. The last two large spikes are after tilting the panels. None of this was very scientific, with the angle being determined by the available size of the angle iron (five feet, cut in half for two 2.5 foot lengths). I estimate this is about a 22 degree tilt, maybe half of optimum.

Qualitatively there is a significant improvement in output, maybe by a third, on sunny days. The two large spikes are the days before and after Thanksgiving, which we’re full sun all day, with Thanksgiving being mostly cloudy.

The lessons: angle is important. Shady days will produce a bit, but full sun is where the real productivity is. Most home installations won’t have too many choices for angle and the weather is going to be even further beyond our control. But some good parameters to get a feel for.