I write this from a place where electricity is provided by a crown corporation (government ran corp - SaskPower) and also have a net-zero rooftop solar system, and small scale solar like this is quite inefficient compared to grid-scale stations. I very much agree that there is some sovereignty in producing one’s own power, however, grid-scale generation is much more effective, both in cost and generation efficiency.
SaskPower has really had no recent incentives for rooftop solar and they only pay about half price for power returned to the grid, effectively discouraging widespread development of rooftop solar.
They have instead proposed an interesting alternative where a homeowner could purchase a portion of a larger scale facility and be credited for the electricity that portion generates. Crowd-funded electricity generation, essentially. This is, of course, much more attractive when the provider is essentially a company owned by the public, not a private, profit seeking entity. But, I think it could be a promising alternative to enable homeowners to offset their electricity bills while being a better option for the overall grid.
Larger scale is cheaper, but rooftop avoids the need for long-distance transmission [in short supply right now in California] and limits the need to convert farmland into solar
small scale solar like this is quite inefficient compared to grid-scale stations.
grid-scale generation is much more effective, both in cost and generation efficiency.
Can you explain a bit better on the magnitude of these differences and why they exist? Thx
Solar panels are most efficient when sunlight hits them as close to perpendicular as possible. Large scale arrays tend to be 1 axis sun tracking, which yeilds about twenty percent more power with the same panels compared to optimal angle fixed arrays at cost of some small motors, a computer, and incresed space between the panels. Small scale and or rooftop by contrast tends to be space constrained, and often ends up at bad angles.
It still works obviously, but between the fixed angle and cramped space you see significant losses compared to what the same pannel could output in a large scale array.
Cost wise, the most expensive part of any small scale solar array tends to be the labor to install it. Panels are now cheaper per square m than fence posts, inverters are expensive but not that expensive, but design and construction are not. It is a lot faster and easier to have a team start at one end of a field and put down racks in assembly line fashion than having someone come out and design a system, another team climb roofs to install conduit and brackets, then a bunch of electrical work, before finally getting an electrical inspector to come out and sign off on it.
None of this is to say that small scale is useless or you shouldn’t do it if you can, especially in California where Pacific Gas and Energy have spent the last forty years outright refusing to do any maintenance or infrastructure investments unless the govement picks up the entire tab and lets them raise some of the highest rates in the nation, but there definitely is an argument to be made that if the government is paying for it either way than spending should go to the place that gives an extra twenty to thirty percent output for the same cost.
Good points.
So this leaves us comparing the inefficiency of fixed-angle panels to the inefficiency of transmission over a grid. IIUC, grid inefficiency is huge. So wouldn’t it be wise to upgrade the home kits to add sun tracking and a motor?
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.)