Hacker News Reader

Comment by stephen_g | Hacker News Reader

Interesting, definitely a surprising result. I did wonder when I saw a thumbnail of a video discussing this on YouTube (but I didn’t have time to watch it) - I thought “Surely that only works for bifacial panels” so makes sense that the article confirms that that’s what they were testing.

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?

View on HN

I'm curious about how well this performs in winter when the sun is low in the sky and you have a pretty big deficiency. Usually you use what ever angle the roof is at (typically 30 - 45 degrees) and leave it at that. By adding a vertical component you may be able to substantially offset the summer/winter difference. Vertical panels won't do much in the summer but that's fine, you'll have a surplus anyway. But in winter you need every little bit. But from a ROI point of view those would be pretty expensive KWh, because the total produced versus the capital expense won't be very high. And in plenty of places the local authorities might have something to say about covering the outside of the building with panels. I'm going to play around with this here to see what it does.

I live in the edge of a row of townhouses and have a huge wall doing nothing but cooling the house. I’ve been thinking about having vertical panels on the wall and my fear is exactly what you described, that all RoI calculations are based on producing a lot of power during the summer half of the year and I that I will not recoup the money but the problem is that when it’s sunny outside everybody is producing electricity and the prices are low so I think the RoI don’t really take this in to account. My wall is on the sout side and gets sunlight all day, is much larger than my roof, doesn’t get covered with snow. The prices electricity are usually 10-20x higher during the winter and our consumption is also 10x higher. I don’t know it just seems to make more sense to put them on the wall.

I think you should factor the savings on AC in the summer and heating in winter as well into your calculation. For that to be most efficient the air would need to be trapped behind the panel, I don't think you need to worry about overheating so much because they are going to be running at a low fraction of their theoretical capacity. There is a fair chance that including savings on heating and cooling it will actually work out but I haven't run the numbers in detail. But it certainly is an intriguing proposition, even if it would work only on South facing walls.

We don’t have AC installed so our only major energy cost during the summer is hot water . Yeah it’s definitely worth doing som maths. One major pain point though is that we need a permit for vertical panels because it affects the look of the house.

> we need a permit for vertical panels because it affects the look of the house

That's fairly common, but usually only on the front of the house. And on extra buildings like a garage or a garden shed such restrictions may not apply. This is pretty trick and it varies enough from one place to another (even within the same country, province or state) that it is worth researching before embarking on such a project.

Yeah, I'm quite curious about the overall tradeoff here. I'm at about 51 deg N and the solar elevation angle gets very very low during the winter (only 16 degrees elevation at noon) but high in the summer (63 degrees elevation at noon). Because of how low the sun is we end up with very long shadows even mid-day in the winter. Would love to spend the time breaking down:

- 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.

Reply on news.ycombinator.com