this post was submitted on 04 Dec 2023
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Yeah, standard installations will often be cheaper than a customized mounting. I'm at 52.9 and have a rooftop system with two arrays directed SW and SE because of rooflines (sized so the house is net-zero - 39 panels for 14 kW which gets me about 15,000 kWh annually), but I'd definitely go ground mount with a summer/winter position rack if I were to do it again. I work a bit with simplified PV modelling now and am disappointed that I didn't know more sooner, probably would've saved quite a few dollars.
We also did an early feasibility study for a 10 MW farm and did find that tracking was marginally better, even including maintenance costs, but that does introduce the risk of labour availability and cost fluctuations that isn't there on fixed mount. Overall, the project wasn't feasible with the rates SaskPower pays.
Our initial plan based on my research was a ground system, not a roof system. South instead of southwest, fewer trees in the way, easy manual angle adjustment, easier to clear snow.
That would have saved us at least one panel and made it easier to add or replace panels.
The "wasted space" would be suitable for storage of various yard tools and equipment or a slightly taller mount might have made a nice shaded patio.
According to the contractors, the cost would have been substantially higher than a roof because of the difference in engineering costs and the legal requirement for fencing. I've since seen enough ground installs to think that the engineering and fencing requirements were not legitimate. I haven't seen a single fenced installation and the support structures all look enough alike that I suspect the engineering is as close to a rubber stamp as a roof install.
We're retired now. Without substantial grants, the window of opportunity has passed. With what I've learned in the last few years, I suspect that a ground mount would have actually saved us enough money to fit our line of credit instead of having to go hat in hand to the bank.
Oh well. Next up is heat pump. A preliminary look at federal funding makes me think that we can manage the capital outlay, leaving our pellet stove for just the coldest days.
There are definitely differences in installation, like piles instead of roof brackets, but I don't imagine there'd be too big a difference in cost as long as there was local equipment to drill for the piles. And yes, I believe fences are only needed for larger installations.
Heat pumps are much more efficient than resistive electric heat, but you won't save utility bills if you already have natural gas heat. Right now, electricity is about 9x more expensive for the same unit of heat compared to NG. I'd otherwise recommend it if you value emissions reductions over costs, though.
Natural gas is not available to us.
Our residential heat (900 ft² mobile home) is a 20-year old pellet stove with occasional use of a space heater in the opposite end of the building. There is no evidence that it's on the way out, but it is 20 years old. We use 150-180 40lb bags of pellets to the tune of $1300-$1500 per year, plus the power used by the stove.
My shop (250 ft²) gets enough heat from occasional use of an external wood-fired rocket stove with heat exchanger for 3-season use. On colder days, I add in the overhead 750/1500 watt electric radiant heater so that I don't have to wait 3 hours for the shop to come up to temperature, but I try to not use the shop when it's colder than about -10C.
My analysis suggests that I can save at least $1000/year on pellets and eliminate the use of space heaters and rocket stove while also making it much easier to heat the shop when I need it. $1000/year (really, 6-7 months) goes a long way to making up the difference between current electrical use and expected electrical use.
And even if I've miscalculated, we can afford to pay a bit more to reduce wood use and resistive heating. One thing I've learned is that the best pellet stoves still put out more particulates than I'd like, and the rocket stove is worse. (Although the rocket stove is far better than the a campfire and people go through a lot more wood for their campfire than I use in the rocket stove.)
Ah, then yes, you'd benefit quite a bit from a heat pump. I'd keep the existing systems as backup for those extra cold days, but otherwise it sounds like a great upgrade, and you get the bonus of cooling in the summer.
Keeping the other systems operational for the coldest days and backup is the plan.
We've done fine with just a smallish room AC, but our heat tolerance is going down as we age, so having a bit more cooling would be nice.