Our wireless, remote, off-site fusion reactor power solution went live on May 12, 2020. We have 7KW of rooftop solar and two Tesla Powerwalls. Since then, we've been 91% self-sufficient in our electricity needs, with 10MWh of net positive energy production overall. (We've generated 10MWh more electricity than the house has consumed since we installed the system.) The 9% of energy drawn from the grid since installation is due to cloudy weather, high demand or some combination thereof.
Overall, I'm pleased with how our system was designed in terms of production and storage. In a perfect world, I'd like to be 100% self-sufficient; but that would require additional capacity (and cost). "Perfect is the enemy of the good."
Since we installed the system, we've added a plug-in hybrid vehicle (RAV4 Prime), and a mini-split heat pump to cool the garage. We're still doing pretty well with production exceeding demand, but it's a smaller margin today than compared with the lifetime totals.
At some point, six or seven years from now, I anticipate we'll be buying a fully electric vehicle, which will place greater demands on the system. It's hard to quantify that, though I suppose I could use our gas consumption as a surrogate. I haven't done a deep dive into how Toyota calculates lifetime fuel consumption, or if indeed it does at all. There's a report on the dash that gives our effective mpg, but I suspect that resets with every fill-up. The last figure I saw was 73mpg.
Our choice to live in Nocatee has placed a high demand on personal transportation. There is no public transit anywhere nearby, though light rail that would run between St. Augustine and Jacksonville with a stop in Nocatee is rumored to be on the horizon. For day-to-day stuff, we're well served by the RAV4's 43 mile EV range. But to go to Jacksonville, we're hitting the tank on the way home every time.
In any event, at least in Florida, it's become clear to me that our vehicles are our greatest energy consumption devices, gas or electric. The house is a fraction of what the car uses, how small a fraction depends on how much driving we do. If we were commuting to work every day, it'd be tiny.
So I'm planning on up-sizing the power system when we get an EV. I spoke to one of the company techs some time ago, and it's possible to simply add to the array. By the time we do this, the Powerwalls should still be near 80% of their rated capacity. So unless there's some big economic incentive to replace them outright, I'll be looking to just add additional battery capacity.
With hurricanes and climate change, and a political climate that is increasingly hostile, this may be all somewhat uncertain, but I think it's wise to plan ahead. So I'm setting up an account now to hopefully save enough to pay cash when the time comes, rather than borrow again. We'll only be a few years from paying off the mortgage by then, so a loan won't be out of the question, but I'd rather not.
Looking at other ways to reduce consumption, I think I'll also be buying a heat-pump dryer. The dryer is a huge energy demand, and it'll be about 10 years old then, so about the time we'd probably be thinking about replacing it anyway. Likewise with the HVAC system overall. Ten years isn't necessarily "end of life" for a heat-pump, but Florida is a harsh environment.
I'm hopeful/optimistic about significant gains battery technology performance and pricing; and more modest gains in HVAC, though our developer-installed system is the minimum to meet building code, so we might make some significant gains there. We've already installed an induction range, and I expect that'll last for several years past this overall upgrade.
I'll be in my early to mid 70s by then, so it'll likely be the last "home improvement" project I'll have to undertake, though there's probably a roof replacement in there somewhere as well. I hope to try to minimize my overall "footprint" in my last years on this planet, short of becoming an ascetic. I recognize the sunk costs of resource extraction, manufacture and transportation kind of stretch out any ROI in terms of karma, but "You do your best, the rest isn't up to you."
Originally posted at Nice Marmot 11:52 Thursday, 29 June 2023