How much was your system?
Assuming that you have some leeway to pay your mortgage off quicker (depending on your exact terms).
Atleast where I live a standard 25 year mortgage can be paid off in ~10 if you were to double up your payments, because all of the additional money you're paying comes off the principal. Thus, the non-interest portion of the payment has _more than_ doubled.
What about on-site battery?
In any case, $15k is still a bit too steep for me, not because I can't afford it but because I want something that'll pay for itself in less than 5 years. My electricity bill is about $150/mo. so a solar roof doesn't make sense financially, even if I'm able to sell the excess to the grid.
Typical systems don’t have a battery, nor do they need one.
The grid is used as the battery.
An off-grid solar installation is significantly more expensive.
At least as of last fall, it was roughly $3/watt for solar installs - before incentives. Right now TSLA advertises about $2.2/watt, which is by far cheaper than anyone else.
If so, at 9.4 kW / 55 kWh per day, I would bloody hope you are exporting to the grid. That is an extreme amount of energy for a single family.
Last summer NorCal had some nasty heatwaves come through, with lots of "red flag" warnings. High winds, high heats. We had multiple days of 110F+. On those days we used more than 55kwh/day.
That being said, the game with solar is that of averages. Right now we're making a lot and exporting a lot. When the summer heats up, we'll be making even more power, but not exporting as much. In winter time we generally need more from the grid than we make.
Hopefully at the end of the year, we'll be near zero net.