Positioning of solar panels...

[Externet]

Greetings.

This is not simple for me to put into words; please ask what I may be missing to expose properly.    For a northern hemisphere latitude chosen as 45⁰ as an average for America, Asia and Europe locations with solar panels.

If the solar panels are placed horizontal, as soon as the sun is above horizon, the panels are exposed to direct sun rays.  At a very low angle but every day of the year and for more than 12 hours in summer but at a 'lossy' incident angle.  There will be a 'bell' curve of exposure peaking at celestial noon, producing a photovoltaic generation of  X KWyear.

If the solar panels are tilted 45⁰ for optimal exposure, at sunrise above the horizon illuminates the back of the panels producing zero energy until the sun azimuth reaches east and until falls at west to again illuminate the back of the panels until sunset. Am I right in this ?  The noon peak is more productive, yields Y KWyear.  In winter, the sun hits the panels as soon as above horizon at a more efficient incident angle.

The consensus is to install them tilted but am curious about how much detrimental to generation (Y-X) is installing them horizontal.  Integration calculus should yield the result but am not capable of performing the operations.  Could you ?

In other words: how much better is a tilted installation ?

Horizontal --> poor angle,  more exposure hours in summer.

Tilted --> better angle, less exposure hours in summer.

Comes from two things... If the photovoltaic generation is for providing heating in winter or cooling in summer. If angling is conveniently justified or not for an existing roof risking windload.

 

[iNow]

Good question 

[Peterkin]

Is it a math question or a practical one?

In practical terms, tilted is better. Ideally, you should be able to adjust the tilt, for time of day, season and weather conditions. But even if it has to be fixed, there is plenty of advice on how to find the best angle.

https://news.energysage.com/solar-panel-performance-orientation-angle/

[Externet]

It is a mathematics question.  Am after figures to compare from integrating exposures at sun azimuths, elevations and incidence angles.  Or that is a wrong way to find out ?

My roof has 4.8KW generation capability, it is slanted for south exposure.  In summer, noticed generation does not start until ~9+am; and even the sun is bright 3 hours before sunset, there is no generation then either.  Guessing, a total of 3 hours by sunrise + 3 hours at sunset are not productive mostly because sun azimuths on tilted panels. Typical production is 20 to 30 KWh daily.

If deserves to relocate post to 'applied mathematics' or 'calculus' please move.

[Image taken from south, near noon]

[swansont]

14 hours ago, Externet said:

If the solar panels are placed horizontal, as soon as the sun is above horizon, the panels are exposed to direct sun rays.

If they are tilted along an axis of latitude, which is what is typical, this is still the case. (I’m ignoring any effect from being raised off the ground, which has minimal impact)

[Peterkin]

59 minutes ago, Externet said:

It is a mathematics question.

Can't speak to that. The practical aspect depends on where you live, and that's what the tables are supposed to tell you.

[Ken Fabian]

It becomes a trade-off between installation costs and maximising output. Cost usually wins out in the end.

This style gains by reducing up front costs (but works best nearer the equator and will not support co-existence with livestock grazing) -

 

 

[Peterkin]

... and doesn't fit on the roof too comfortably...

[swansont]

8 hours ago, Ken Fabian said:

It becomes a trade-off between installation costs and maximising output. Cost usually wins out in the end.

This style gains by reducing up front costs (but works best nearer the equator and will not support co-existence with livestock grazing) -

 

 

Where is the site where that picture was taken? I've not seen that configuration, and am interested to know the latitude and orientation

[Ken Fabian]

@swansont They unpack E-W, ie the peaks/valleys are running N-S, which gives good morning and afternoon insolation as well as middle of the day - though solar panels laid flat would get similar sun exposure. Better angled I think to shed rain (and dust?) and structurally stronger; the pic looks like a desert site. Not sure now where that pic came from or it's location. Apparently there are installations all over the Australian mainland and around the world already - one in the Atacama desert in Chile. Not all in deserts. It does look like the kind of innovation needed to grow clean energy fast enough to reach net zero goals in a timely manner.

It's actually a portable solar farm system, easily moved from one location to another. The company is 5B, Maverick is the name they give their rapid solar deployment system - “100 kilowatts fully installed before lunch, and 1 megawatt in a week”. They pack more panels into a given site area which delivers higher output than fixed angled style - claimed at 180 - 200%, equivalent to single axis tracker systems but at the cost of more panels, made up for by big savings on installation. I assume they will work best nearer the equator; they will work at other latitudes.

[swansont]

39 minutes ago, Ken Fabian said:

Better angled I think to shed rain (and dust?)

That makes sense. You want the water to drain, and take the dust with it, for rain and possibly the occasional cleaning in the absence of rain.

Of course, if it's not near the equator and it's angled in the orthogonal direction, then you don't need to do this.

[Peterkin]

Where we live, in Ontario, we not only track through the day, but can tilt the array from fully horizontal in case of high wind to fully vertical to shed snow.

Those adaptations become increasingly important as we have more and wilder weather events.

There is a growing advantage, too, in distributed, small, stand-alone array/battery/controller sets, since above-ground grids are extremely vulnerable to breakdown (in addition to the loss in transmission, c. 5%) and difficult to repair in bad weather, which means a great many homes are left in the dark, maybe for days, when a component breaks down or there's a big storm. In the UK, some power lines are underground, but over the kind of distances we have in the US and Canada, that's not practical.  

You're much more secure with your own home system, even if it's not optimally efficient.

[Ken Fabian]

On 8/23/2022 at 8:33 AM, Peterkin said:

Where we live, in Ontario, we not only track through the day, but can tilt the array from fully horizontal in case of high wind to fully vertical to shed snow.

Those adaptations become increasingly important as we have more and wilder weather events.

There is a growing advantage, too, in distributed, small, stand-alone array/battery/controller sets, since above-ground grids are extremely vulnerable to breakdown (in addition to the loss in transmission, c. 5%) and difficult to repair in bad weather, which means a great many homes are left in the dark, maybe for days, when a component breaks down or there's a big storm. In the UK, some power lines are underground, but over the kind of distances we have in the US and Canada, that's not practical.  

You're much more secure with your own home system, even if it's not optimally efficient.

It sounds like Canada needs to put power lines underground because the costs of not doing so are so high. Self reliance for rural homes or communities is good but a different problem than reliable supply for urban centres and industry that are important too. To what extent can Canada's grid make use of US energy sources and interconnectors? And vice versa? 

The nearer to the Arctic circle the more seasonally limited solar is going to be. The more extreme the weather conditions the more significant the ways they are mounted become and more expensive. The concertina packs of solar above are going to work well in Australia and much of the world but not everywhere.

Wind and hydro may always be more necessary for Canada than for nations like Australia. I'm not a big fan of nuclear but nor am I strongly opposed; it will have it's place too but it will be up to people who are it's fans to do the promoting - preferably with greater distancing from pro fossil fuels climate science denier politics, that turns it into an anti-renewables rhetorical position more than an actual emissions reductions option. I am not sure if State mandates and guarantees for nuclear are any more palatable to nuclear's more vocal backers than steep carbon pricing that will probably - inadvertantly - aid renewables more than nuclear.

[swansont]

6 hours ago, Ken Fabian said:

It sounds like Canada needs to put power lines underground because the costs of not doing so are so high.

There may be issues with that when the ground freezes and you can't dig up lines that need attention. Plus, digging is expensive and as Peterkin notes, that's a big issue when long distances are in play

[Peterkin]

7 hours ago, Ken Fabian said:

sounds like Canada needs to put power lines underground because the costs of not doing so are so high.

This is doable in the city; not across many thousands of miles of mountain and tundra.

 

7 hours ago, Ken Fabian said:

Self reliance for rural homes or communities is good but a different problem than reliable supply for urban centres and industry that are important too.

No reason cities can't have local energy generation, each depending on where it is and what's most readily available. No reason each church and factory can't have its own solar array - as many already do.

 

7 hours ago, Ken Fabian said:

To what extent can Canada's grid make use of US energy sources and interconnectors? And vice versa? 

The US is buying lots of elecricity from Canada, especially Quebec, if I recall correctly, but the grid is the problem, not the solution.

 

7 hours ago, Ken Fabian said:

Wind and hydro may always be more necessary for Canada than for nations like Australia.

Yes, and tide and thermal - whatever works best in each locality. And a lot of smart, inventive people are working on a lot of different projects. It should have been started half a century ago, instead of those large subsidies to the oil and gas industry - by now, we'd really have made progress. 

Here's a taste. https://www.cdp.net/en/cities/world-renewable-energy-cities

A great site for stats, btw.

[Ken Fabian]

11 hours ago, swansont said:

There may be issues with that when the ground freezes and you can't dig up lines that need attention. Plus, digging is expensive and as Peterkin notes, that's a big issue when long distances are in play

How are underground water and sewage lines managed and repaired in Winter? Buried deeper in colder parts but wait till Spring to do repairs? That trade-off between building better and the maintenance requirements and costs of outages will always be there.

@Peterkin I do think long distance interconnectors are going to be increasingly important to decarbonising electricity - and electricity will be important for decarbonising other energy requirements. I am not familiar with Canadian conditions and am not claiming I know better but I am doubtful that local self sufficiency will suffice; I think improving reliability of interconnectors will matter a lot. The best positioning of solar farms for Canada may be in Nevada.

[Sensei]

Do you want to know what I think?

The future of home is solar roof tiles.. https://www.google.com/search?q=solar+roof+tiles

i.e. the entire area of roof is one huge solar panel seamlessly merged with roof..

 

Edited August 26, 2022 by Sensei

[Peterkin]

49 minutes ago, Ken Fabian said:

How are underground water and sewage lines managed and repaired in Winter?

With great effort, difficulty and expense. But they good news is, they rarely get damaged in winter. And, obviously, they only exist in municipalities, not in the wild country, where snow may build up 12-14' deep and hard packed. 

 

51 minutes ago, Ken Fabian said:

The best positioning of solar farms for Canada may be in Nevada.

Wires all the way through Tornado Alley? Don't think that's such a good idea. Especially at 1% loss per 100 miles of wire.

It's a pretty solid box, but some people have poked holes through the side. Of course, there is the unmentionable aspect: Reduce Demand!

50 minutes ago, Sensei said:

The future of home is solar roof tiles.

Yeah! And this stuff! https://www.solarfabric.com/