A couple things to add to sonori’s reply, the system efficiency also goes up when you can use higher capacity inverters. Essentially, one grid-scale facility (say, 100 MW) will have far fewer inverters than 100 MW of rooftop systems, meaning less efficiency loss.
While larger facilities can be optimized for azimuth and sun angle or with tracking, rooftops are often not optimally aligned, leading to a decrease in capacity. Sure, you could add tracking to your residential system, but that’s a significant cost that many homeowners won’t see the benefit of. There might also be obstacles that shade a residential system, which is often addressed when selecting sites for larger systems.
I’m not disagreeing with anything you’ve said, but there is a bit of nuance on optimal angle. I’m also in SK (about 50.7 degrees), and when I was looking at putting up panels, it was cheaper to throw a couple of extra panels up than to modify the install for “optimal fixed angle”.
Obviously, starting from scratch, you’d be foolish to not include “optimal fixed angle” or maybe even a manually operated dual-angle system that has a “summer position” and a “winter position”. For my install, a dual-angle install would have required the same number of panels as an optimal fixed angle. I would have got a larger margin of overproduction, but not by enough to eliminate a panel.
A lot of what I see on solar panels is still stuck using the same analyses as when they were less efficient, more sensitive to clouds, and more expensive. It wouldn’t surprise me to learn that even large scale installations would be better served by eliminating the expense and maintenance costs of tracking instead of pushing for maximum performance.
(Note: we didn’t ever get the install, because we couldn’t get financing, even when SaskPower was still doing full retail buyback.)
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.