It's that time of year again when I learn why I'm not completely off the grid. The last few weeks we've had about one partly sunny day. Most of the time it's been completely cloudy. This is the winter hump that kills solar electric systems.
Most of the year I'd be able to get by. Once in a while we get these winter stretches almost totally lacking in direct sunlight. Worse yet, it's snowed just enough every day to keep the solar panels under a white blanket.
The early part of last summer was bad. It rained almost every day. Even then, the solar electric system made some gains. Days, while cloudy, were long. While I took the opportunity to top off the batteries from the grid, it wasn't absolutely necessary.
This time of year, it's necessary. Not only is solar gain at its minimum, usage is up. It's dark early so the lights come on. Everyone is inside more so the stereo and computers get more use. Even the amount of laundry goes up. In the warm months, there's very little to wash -shorts and T-shirts. In the winter, we bundle up, and every one of those additional layers makes for more laundry. (or evil smells in a closed up house, your choice)
Without supplemental power, the battery bank would suffer. Leaving batteries partially discharged for long periods of time shortens their life. I really don't need the expense or aggravation of replacing them early. Worse yet, it's easier for the battery bank to get cold. Cold batteries hold less electricity than warmer ones. That's another reason cars start so hard, or fail to start, during cold winters. There's more need for extra power to turn jelled grease and engine oil at the same time the battery is at its weakest.
I may still pull the plug on the grid, but I'll need some battery survival strategies. Could get a back up generator. A diesel one would be nice. It could even run on heating oil, or converted to run on waste veggie oil. Any generator would need to be quiet, even if that entailed building a custom muffler.
It would be necessary to keep the solar panels absolutely clean of snow. A push broom on a very long handle could do the job. That would allow my system to harvest every watt of available power.
Then there's the option that I actually used for a couple years. I killed the main utility breaker and used no grid power in the winter. All I had to do was drain all the water out of the plumbing, load up the car and drive south. Nothing like pitching a tent on a southern beach for the winter. That works too.