Angled mounts tend to have obnoxious cross-members that block the airflow that should otherwise be sliding up the back of the panel, particularly on roofs where there's basically a bed of hot air trapped underneath with no good way to escape. That boosts the panel temperatures even further than you'd assume given simply lower convection based on their angle alone. Vertical mounts cannot have framing in these places, so they don't.
I agree that, when you factor in semiconductor physics, it's not a mystery but it isn't necessarily an intuitive result for most. I've been working in aerospace for 5 years and one of the things that has been very clear to me is that peoples' intuition about things breaks down very quickly when there's non-linear factors involved in an analysis. In aero it's primarily square-law/cube-law tradeoffs; in semiconductor physics it'll be more exponential.
For this particular problem you've got an exponential (semiconductor behaviour as a function of temperature) multiplied by a trig function/dot product (cosine of the angle of the sun relative to the normal of the solar panel), with a bit of natural thermal convection thrown in for good measure. Modelling this (digital twin, as they call it) is feasible but it's not something most people are going to have a good intuition on with respect to where the sweet spot is going to be.
[0] https://www.sciencedirect.com/science/article/pii/S187661021...
The increase in yield from going near vertical (80 degrees was the best I could achieve using existing mounting gear), has been about 20% - I say about as I haven’t done a scientific study of it, just looking at year on year comparisons for cloudless days, and the panels are 60 C cooler, which is far better than I had hoped for.
"Oh, it's convection."
"Hey, I wonder what the best in-between angle is, balancing both temperature and cosine loss."
Make sure they face the right way (south for Northern hemisphere), and match the angle with your latitude. If you have a pitched roof thats +-10 deg in the correct angle, just lay them flat on the roof.
Edit: forgot to add, a while back there was an article here about a company that proved it was viable to lay the panels flat on the ground for massive solar farm installations. The savings from less installation labour and materials went to installing more panels. And they still came out ahead. Solar is getting cheap enough that the math gets weird. Your answer is almost always "just add more panels" unless you are seriously space constrained.
[1]: (https://www.solablock.com/, looking for investors!)
CMUs and other pre-cast concrete "lego blocks" have intrigued me for a long time. These look like they've got more robust interlocking features than conventional cinderblocks too? The idea of being able to order (even without the solar) say 8'x4' pre-cast "CMU-style" walls, have them show up on a flat deck, stuff rebar and mortar into ready-made holes, and grout between the blocks seems like it could dramatically speed up a lot of exterior construction. Being able to get them ready to wire for solar is delicious icing on the cake!
They make tiles and cinderblocks, and yes, they have some interlocking features. And yes, the idea is that installation will be way easier and cheaper than first building a regular wall and then attaching vertical solar to that after the fact.
I was more distracted by that behavior and totally failed to get any value out of visiting your site.
The other factor is that (compared to where I live in Australia at least, but also all of the US too) the Netherlands is quite far from the equator, so I expect there would be a crossover point a bit closer to the equator where you start to get less efficiency than standard angled horizontal panels?
Although perhaps with some reflectors on either side it might still work with a vertical bifacial panel (in areas closer to the equator), maintaining the cooling advantage?
- land area required for tilted vs. vertical
- net production over the year
- equipment cost for bifacial panels vs single-face panels
Anything that helps solar cost/performance is a huge win around here because we have max energy consumption in the winter when solar doesn't produce a whole lot.
(A "(possibly accidental) gatekeeping dick move" :P )
https://www.zdnet.com/article/why-13-year-olds-solar-power-b...
https://web.archive.org/web/20160308193750/http://www.wsj.co...
Combinations of different orientations can smooth output over a day or year, which could reduce the mismatch between module output and inverter capacity.
> “For a standard system, we observed that under high irradiance conditions, the increase due to the light is offset by the decrease due to the higher operating temperature,” Van Aken stressed. “However, for the vertical system, we observed that the operating temperature is not increasing so much and the voltage increase and decrease are more or less balancing.”
Facing the bright sun increases temperature enough to offset the gains in voltage (since temperature increases presumably increase resistance if my EE101 classes hold in this era). Not facing the sun? Less heat -> more total power throughput.
This already being done on dams in the UK and Spain (or was it Portugal? Maybe both.)
If they were on a pole allowing the wind to turn them, could you get both wind and solar power at the same time?
