Are tilt mounts worth the investment?

[J.P.M.]

I'm in the Phoenix area.

Every situation is a bit different than the last. Sometimes tilting with or without adjustments will result in more production. Other times a smaller system for the same output with less seasonal oversizing can be the result. Other times, it will not make sense. We're not all in Phoenix.

[HX_Guy]

This is actually inline with the 5% gain the website I referenced.

If you get a lot of snow, the gain could be a lot bigger, but it's hard to estimate.

I'm in the Phoenix area.

[NetComrade]

Adding up all the months, it would produce a total of 2321kWh with adjusting twice per year vs a fixed angle at 31º of 2222kWh. So basically 100kWh additional, that's nothing.

This is actually inline with the 5% gain the website I referenced.

If you get a lot of snow, the gain could be a lot bigger, but it's hard to estimate.

[J.P.M.]

Depending on the application, areas with a lot of seasonal variation in available sunshine, with less availability in winter, either from high latitude (shorter days & lower solar alt.), or winter clouds, or both, may benefit from tilt adjustment schemes and/or elevated tilts.

Lower latitudes with year round sun are more likely to see less benefit from adjusted tilt schemes and are probably, as a 1st approx., for PV anyway, better off facing mostly south at a fixed tilt slightly less than the latitude.

Northern climate solar thermal, or passive solar is probably better off at a lat. + 15 deg. or more tilt, with azimuth adjusted for something like common daily winter cloud distribution - for example, a frequent pattern of clear mornings/cloudy afternoons would shift the optimum array azimuth somewhat to the east. As usual, this ain't rocket science.

[Jason]

+ 1 from me, we have messed around with this stuff for years now, it makes f@#!$ all difference in most of the scenarios we have run

[HX_Guy]

Did a quick analysis and well, doesn't look like messing with it is worth it.

The 4 panels would equal 1.24kW and would produce these numbers based on 3 different tilt angles. The green highlights are the best for each month at different angles.



There would really be no point to adjusting more than twice per year, so this would be the summer and winter angles...



Adding up all the months, it would produce a total of 2321kWh with adjusting twice per year vs a fixed angle at 31º of 2222kWh. So basically 100kWh additional, that's nothing.



BTW the cost to add the 4 panels I estimate to be around $1.60/watt. Will need to see after a year of the current setup if the extra panels are needed and what the ROI on them would be.

[NetComrade]

Seasonal tilts can be a PITA, but 2 X/year may be doable, or at least less onerous. Fixed works almost as well depending.

http://solarpaneltilt.com/ says 2x gives you 5% extra, 4x not worth it. If you have a 15 degree loop, tilting does not sound like a horrible chore to me.
But I don't see a lot of tilt mounts commercially, other than for RVs

For heating panels it's a good suggestion, sounds like a permanent tilt though.

Thanks for getting the conversation back on track.

[bcroe]

Tilt?

Are there any manual telescoping tilt mounts on the market? Maybe something like this where you could manually adjust the tilt?

I'll most likely be adding 3-4 more panels on a flat part of my roof (patio cover) in the future and it would be a good spot for an adjustable tilt mount, though for only 3-4 panels, not sure if it would worth the effort. I guess I can run it in PVWatts and see.

Of course we with snow have another motive for seasonably elevating panels. Here the
south facing panels would benefit most from variable tilt.

I found a telescoping element might need a ratio of 3 to 1 extended to closed. That means
it must have multiple sections to cover the range. Or the back end extends far beyond the
array (into the ground for me). Besides the complicated construction, there is the issue of
strength when fully extended. I came up with a beam that sort of "unfolds" to the maximum
length, from one piece to 3; the center one is the strongest. But that still left me with the
issue of pushing 400 lb into position, then climbing 10' in the air to disconnect the pusher
beam (to my tractor?). No place for a ladder there. That is 6 panels at a time.

Right now I'm thinking a center height pivot (door hinge?) might be better, keeps the weight
off the tilt driver. Needs more work.... Bruce Roe

[J.P.M.]

I have penciled this out a few times. The extra cost of tilting/tracking systems just does not return when you put the cost savings of fixed mount into more panels and production. The decreasing cost of panels is only exaggerating the effect.

The KISS effect is also in play. Screwing around with tilt angles 2, 3, 4 times a year is just not worth it.

While I'd generally agree with that statement, I've found it can not only be cost effective, but in some applications very cost effective to tilt panels, maybe even a no brainer.

For example, solar thermal collectors in a usually cold climate with snow for ground cover over a significant portion on the year. Tilt at lat. +15 deg., size for for op. winter heating and reduce summer overheating.

Or, most applications, thermal, PV or passive solar at high latitudes.

Or, places like Albuquerque with a lot of flat roofs and a boatload of sunshine, pretty much year round. There are a lot of tilted arrays to be seen on homes in the land of enchantment.

Seasonal tilts can be a PITA, but 2 X/year may be doable, or at least less onerous. Fixed works almost as well depending.

[DanS26]

I have penciled this out a few times. The extra cost of tilting/tracking systems just does not return when you put the cost savings of fixed mount into more panels and production. The decreasing cost of panels is only exaggerating the effect.

The KISS effect is also in play. Screwing around with tilt angles 2, 3, 4 times a year is just not worth it.

[J.P.M.]

I think using something like that telescoping channel will work to change the angle of panels. The problem is what to use to raise and lower the panel, and how many panels (based on the total weight) can be moved using a single "lifting" device. If the panel structure is heavy I would think some type of hydraulic piston could do the trick but at what cost? A "worm" gear or "jacking" mechanism would be slow and a lot of work.

If the panels were ground mounted then pivoting them around a center point would reduce the weight and the power needed by the lifting device. Again what is the cost to install this type of single axis "tracking or tilting" device to get a higher % production as compared to just adding a few more panels?

What I have read is that more and more of the large Utility sized arrays (> 50MW) using thin film panels are installing single and dual tracking systems. Maybe they found a way to reduce the install & maintenance cost of the tracking hardware so the additional solar production can at least off set it.

In single point systems, the weight added to make the members stiff/strong enough to withstand the longer bending moment arms and thus the (often governing) wind induced bending moments often makes such designs less safe, practical and cost effective than multipoint systems. Note that with the exception high temp. applications, most large commercial PV arrays that use tracking logic are usually single axis.

Also, for most reasonably sized residential applications, any tracking is usually not cost effective, and thus not usually done by folks who know what they're doing and why.

[J.P.M.]

I know about PVWatts and have used it, but I remember you have to enter your own figures for tilt...it doesn't calculate the optimal for you...or does it?

No, it does not. Start with south facing azimuth and tilt at your local latitude, maybe a few degrees less. Change the azimuth by, say 5 deg. in either direction, keeping the tilt at latitude and see what you get. After a few runs you'll zero in on an azimuth. Then do the same for tilt at the azimuth you just found. Takes about 10 min. once you get familiar with it.

[SunEagle]

For my specific setup, the 4 panels would actually be individual panels, like this:

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So the weight wouldn't really be an issue. It may need two people to do it, one to hold/lift the panel while the other removed the bolt and repositions it.
Thing that could pose a problem though is the length of the square tube...to go from say a 10º tilt in the summer, which would need a very short length, to a 50º tilt in the winter, which would need a long tube. It may be easier to just have tilt legs of different lengths that are swapped out for each season. Again though it needs to be evaluated if the effort is worth it.

That arrangement would be easy to move each panel individually as long as the bottom "pivot" point was smooth and getting the panel to stay in place at the higher angle was quick.

You might have to do some wind loading calculations for the roof attachments to make sure the higher "winter" tilt position didn't make those panels into a big sails during a storm.

[FishGun]

Most of the cost in my designs was in the pivot point. I was going to use a flat pc of bar with holes in it for the brace. Or a tractor top link.
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[HX_Guy]

For my specific setup, the 4 panels would actually be individual panels, like this:



So the weight wouldn't really be an issue. It may need two people to do it, one to hold/lift the panel while the other removed the bolt and repositions it.
Thing that could pose a problem though is the length of the square tube...to go from say a 10º tilt in the summer, which would need a very short length, to a 50º tilt in the winter, which would need a long tube. It may be easier to just have tilt legs of different lengths that are swapped out for each season. Again though it needs to be evaluated if the effort is worth it.