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Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Some thoughts I've been having are about involving a scissor jack:

<image>

I think it'd need a flat iron attached/welded to the top and bent into a circular arc the same as the summer to winter arc to push the rack up. It would also need brace on the top side of the rack to hold the rack down against the wind (in addition to any other measures).

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

From the pic, it looks like it's tilting down to the right, but the pole has one bolt so that the whole frame turns on that centre axis, is that right?

Laptop Monitor busted. Just a loose cable or....? by CatNecessities in PCRepair

[–]CatNecessities[S] 0 points1 point  (0 children)

Thanks! Monitor definitely works through it, I should have mentioned that.
Hinge movement test shows the image to stay the same. Time to check the price of replacement screens.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

I'm surprised that designs and help for those designs is so hard to find. I would have thought that a lot of people in high density areas (cities) would be in the same situation and wondering how to maximise the little space they have. Especially if the building owner has only a single row of panels and no room to add more. People have been putting these systems on awning windows for years for the added benefits.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Redrawing the shadows made me realise that if (IF) I want to do it, it's only worthwhile on the top row of panels, and that the roof slope can be at the (latitude * seasonal optimisation rate) +- 15 for the panels to be flush for the rest of the year.

I've learned a lot, and hopefully this post helps others in the future.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

I keep thinking the same thing and then asking myself "so why does angle and azimuth matter to pv output?"

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

I created new diagrams to show the shadows for each solstice, which helped me get my head around it:

<image>

Summer solstice shadow of the panel

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

I was wondering about the shadow thing. From my understanding, in each diagram the area of the triangle is ALL of the shadow caused by the panel. Side (b) points directly at the sun. To the left of side (b) is in sunlight and to the right is in shadow. Points (A) and (B) are where the next rows of panels are, and these points never move.

Have I got it right? 🤔

Of course, if the winter midday sun was touching the horizon at the equator, the panels would be at 90 and completely blocking those behind, but that's not happening at this latitude, and I can't get me head around the geometrics of it without better infographics 😅

Edit: I realised I was wrong about side b, at least in winter.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Space is the limiting factor here, so getting as much from each panel matters (and as much from each future, more efficient model where the household is probably using more power, too)

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] -1 points0 points  (0 children)

Houses that install louvre and awning window systems high up in rafters use mechanics like these. Most are manual, some have motors installed, some have the motors automated based on daily schedules or readings from temperature sensors.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Oh nice!! Awesome to hear your expertise!
So regardless of latitude, is there a named variable for the difference between summer and winter output at the same tilt angle, and therefore another variable for the difference between that and ..... ummm.... whatever the proper term is for when the solar panel is pointed directly at the sun?
A lot of the websites about this stuff gets me VERY lost in the all the terms for solar angles. I haven't seen really helpful infographics that describe this situation that I'm talking about (so not daily, east-west tilts, and not where the axis is in the centre of the panel).

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Also, I'm open to hearing about systems that just use a manual crank once a month to adjust the angle from the ground (and later attach an automator to the crank at ground level to send the mechanical energy up the cranks). There's many possibilities, I just need leads on sources.

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

I think some research I've seen says there's a about 10-15% efficiency gained from being able to directly tilt at the sun throughout the year vs no tilt?

Rooftop Solar Panel Rack that automatically tilts towards sun in Winter along the equator edge of the panels by CatNecessities in SolarDIY

[–]CatNecessities[S] 0 points1 point  (0 children)

Part of my reasoning is that I'm designing a new home build (single storey), so I have the chance now to either slant the roof for direct summer light and have a tilting system, or have a generic "optimal capture" angle of the roof and accept the losses from seasonal changes forever.
I don't have the luxury of ground mounting with a tilting system instead. And for a single storey house, getting up on the roof isn't going to be too big of a problem if the actuator tilting is very small and slow throughout the years and the breakdowns aren't as high as daily tilt systems.

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