Winter Solstice, Batteries and Battens

June 21st, 2017

So it’s winter solstice. Shortest day of the year. 

“How is that Tesla home battery going?” We hear you ask. “Show us some more graphs!” You say.
Well. Ok then. But first, here’s a photo of our kitchen being clad… still in progress.


Kitchen cladding underway, Australian hardwoods mixed sizes. Rainy day and power tools impacting the generation in the graph for 20th June.

In summary –
The battery still matches our usage IF we are careful about our use. It’s been raining here for a couple of weeks on and off so the green / blue charts are jagged (with less generation) than sunny days which tend to form a smooth bell curve.

Monthly solar generation from our 5kW array. Generation dropping through winter with the wet weather, east facing array, and lower sun with shorter days.


Shows the amount of energy we imported from the grid (in red) far outstripping that we generated (green) or used from our battery (blue) on a rainy day when we also charged the car.


Shows the generation and battery balancing the usage – the numbers at the top show the imports and exports match up pretty nicely. We didn’t charge the car today and it didn’t rain as much.

The 3 charts attached show the 
  1. Monthly generation since November. Reduced generation in winter with both rain and with east facing solar panels (not ideal)
  2. Chart with lots of red shows what happens when it rains and we also charge the car a couple of times in the day. Our use significantly outstrips what we generate.
  3. A typical sunny then rainy then sunny day where we only use what we generate – little red in this chart. We use the dishwasher, washing machine, computer, tv, heater and trades using power tools to add new cladding to our kitchen (did we tell you about our new cladding!) Oh, ok, in progress photo attached.
Overall we expect to export through the year far more than we use. And to do so generally at peak demand times (when most ac’s are running.) But through winter as expected it’s much tighter when the storage capacity of the Tesla home battery is underused due to dropping generation!