Summer solstice

Longest day of the year?

PhotoPills screenshot showing time/date for equinoxes and solstices.

Today is the summer solstice (in the northern hemisphere). More precisely, the solstice occurred at 5:15am here in the Eastern timezone. The summer solstice is the moment at which the sun has ‘traveled’ to its northernmost latitude, in its annual cycle of apparent movement to the north in summer and to the south in winter. (It’s a great day for those of us with solar panels, because it means we’re getting hours of sunlight!) Read on.

Continue reading “Summer solstice”

Alpine view

All the Alps in one view.

Zürich woke to yet another cloudy morning, as the sun rose on winter solstice. On this, the shortest day of the year, we hopped on a plane to Washington, DC, following the sun to the west. Flying high above the clouds, we enjoyed daylight for 15+ hours, though inside the plane we never really got to enjoy the sunshine. When I checked out the window, soon after we reached cruising altitude, I was blessed with a grand panoramic view of the Alps – the French, Swiss, and Italian Alps – spread out beyond a sea of clouds.

The Alps, seen from the airplane leaving Zurich… with low clouds covering all the lowlands.

Summer Solstice

Maximal sun makes maximal power.

Today is the summer solstice in North America, so I was especially interested to see how our solar tracker managed on the longest day of the year. A few weeks ago we doubled our battery storage so we could extend our independence from the grid. Given the extended daylight (15 hours and 27 minutes, from 0507–2034), and the extra battery, the batteries can now last through until sunrise. Although today’s weather was not purely sunny, the system produced over 50 kWh.

In the graph below, the green line shows the battery level declining in the early hours, and climbing after sunrise. The dark blue region shows the house consumption, and the gold region shows the excess solar production… used first to replenish the batteries, and then, after 2pm, to feed back to the grid.

Today was a good day… but not the best day yet. Two days ago was more sunny, and we set a personal record for solar production: 58.58 kWh: