Are tilt mounts worth the investment?

[NetComrade]

If yes, what do you recommend?

Going by http://solarpaneltilt.com/ my optimal is about 12 degrees in summer and 59 degrees in winter (i am roughtly at 40 latitude)

I would like to build a flatter roof (4/12 is 18 degrees, but I am a bit (12-15 degrees) south west so slightly higher pitch would probably be to my benefit.

I like flatter roofs as it's easier to walk on them (and install/service solar). In the winter we do get some snow, so having the panels at 50+ degrees should take care of that problem.

[HX_Guy]

Where on Solartilt.com were you able to find what your optimal angle is?

EDIT: Was able to find a formula on a different site to optimal tilt which basically says:

Winter - Take latitude, multiply by 0.9 and add 29 = optimal tilt
Sumer - Take latitude, multiply by 0.9 and subtract 23.5 = optimal tilt
Sprint/Fall - Take latitude and subtract 2.5 = optimal tilt

For my location in the Phoenix area with a latitude of 33º, my optimals would be:

Winter: 59º
Summer: 6º
Spring/Fall: 31º

Interesting that summer is almost flat. My roof angle is a pretty shallow 17º so it's pretty good for summer, not so good for winter.

http://www.solarpoweristhefuture.com/how-to-figure-correct-angle-for-solar-panels.shtml

[NetComrade]

Where on Solartilt.com were you able to find what your optimal angle is?

Oops. I should have said http://solarpaneltilt.com/.
Edited in original.

Whatever the optimal is, they seem to be worth not so much the 5% potential gain, but the roof convenience to service/clean/install.
Wouldn't it also be easier to service the roof too?

The additional cost might be more space required, but that's OK, I like being able to walk between my panel rows.

How much more expensive are they, and do they have the long term durability.

[HX_Guy]

Hmm, interesting, that site gives slightly different results. According to them...

Summer = 10º
Winter = 48º

Would be cool if there was a website where you could input your latitude, your roof angle, and your azimuth and have it tell you on which day of the year you would have the best solar performance.

[NetComrade]

with tilting mounts you can always experiment

[sensij]

Hmm, interesting, that site gives slightly different results. According to them...

Summer = 10º
Winter = 48º

Would be cool if there was a website where you could input your latitude, your roof angle, and your azimuth and have it tell you on which day of the year you would have the best solar performance.

You mean a site like pvwatts, which gives hourly output? I'm surprised you've been on the forum this long and not seen it. Of course, not every day in the weather file they use is clear, but you should still be able to estimate the maximum with it. Nrel also makes a spreadsheet available if all you want to see is clear sky irradiance, but it takes some work to convert that to array power.

[HX_Guy]

You mean a site like pvwatts, which gives hourly output? I'm surprised you've been on the forum this long and not seen it. Of course, not every day in the weather file they use is clear, but you should still be able to estimate the maximum with it. Nrel also makes a spreadsheet available if all you want to see is clear sky irradiance, but it takes some work to convert that to array power.

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?

[bcroe]

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?

PVWatts will give you an overall estimate of performance for a specific array. But it is pretty useless to
optimize hour by hour situations, because it keeps cranking in an arbitrary amount of weather into the
numbers. About the only way I found is to find a near cloudless place (Death Valley?) around the same
latitude, and use numbers from that.

Tilting between seasons works, and reduces snow accumulation. My east & west facing panels are fixed,
but south facing could benefit from seasonal or even hourly tilt. The idea of doing much on a roof
doesn't appeal to me. Bruce Roe

[sensij]

PVWatts will give you an overall estimate of performance for a specific array. But it is pretty useless to
optimize hour by hour situations, because it keeps cranking in an arbitrary amount of weather into the
numbers. About the only way I found is to find a near cloudless place (Death Valley?) around the same
latitude, and use numbers from that.

Tilting between seasons works, and reduces snow accumulation. My east & west facing panels are fixed,
but south facing could benefit from seasonal or even hourly tilt. The idea of doing much on a roof
doesn't appeal to me. Bruce Roe

Useless is a pretty strong description. The weather isn't arbitrary, but representative of what might be seasonally expected, and it is pretty clear looking at the output when the weather is affecting it. That aside, a calculator that shows optimum orientation for irradiance is here (thanks Amy@AltE). Note that their tilt angles are complementary to how we normally discuss them... horizontal is 90 deg and vertical is 0 deg.

[HX_Guy]

Not quite what I was looking for.

Basically my panels are at a 17º angle...I want to know on what day during the year they should perform at their best. I guess the link in the above site gets me pretty close, though I'm surprised it says the best summer performance is at 19º while the other site was either 6º or 10º.

At 19º, it says the best irradiance is pretty equal in May and June with may being 7.26 and June being 7.24.

PVWatts, at 17º, actually says that June is a better month with 8.09 while May is 7.91. I can't believe February is such a lowly 4.73, system has been doing pretty good on full sunny days. I'm not familiar with this irradiance at all...is it linear as in 8.0 would produce twice as much energy that day than a 4.0? Or in my case, the 8.09 is 1.7X as much as February's 4.73? So if I can hit 60kWh on a clear day in February, it would be realistic to see 103kWh in June?

[sensij]

Not quite what I was looking for.

Basically my panels are at a 17º angle...I want to know on what day during the year they should perform at their best. I guess the link in the above site gets me pretty close, though I'm surprised it says the best summer performance is at 19º while the other site was either 6º or 10º.

At 19º, it says the best irradiance is pretty equal in May and June with may being 7.26 and June being 7.24.

PVWatts, at 17º, actually says that June is a better month with 8.09 while May is 7.91. I can't believe February is such a lowly 4.73, system has been doing pretty good on full sunny days. I'm not familiar with this irradiance at all...is it linear as in 8.0 would produce twice as much energy that day than a 4.0? Or in my case, the 8.09 is 1.7X as much as February's 4.73? So if I can hit 60kWh on a clear day in February, it would be realistic to see 103kWh in June?

Probably not. Read the documentation. Look more carefully at the hourly output. Depending on the weather, your best day might come between the end of April and the end of May.

[SunEagle]

Probably not. Read the documentation. Look more carefully at the hourly output. Depending on the weather, your best day might come between the end of April and the end of May.

I guess temperature is a factor because it would be cooler in those months. You would get more sun in June but at an elevated temperature.

There are way too many variable to accurately predict production output with weather being the biggest factor.

[FishGun]

I don't think you can justify the added cost of the tilt mechanism...at least in my area (about 43lat).

I ran PVwatts for all angles from 0-65deg in 5deg increments keeping all other parameters the same. Then I added up the total production for my best angle (35deg) and compared to a summation of the 3 best other angles (sum-15deg/fallspring-35deg/win-55deg). It was about a 3% gain. 12 adj gave about 4.5% gain. You could do the same for your area.

Snowshedding is something I didn't take into account. No doubt sitting at 55-60deg for a couple months would give some more production...if you are in a snowy region of course!

I built my ground racking/mounts and tried to make it work but couldn't really come up with a cheap strong design that I was comfortable with.

Went to a couple alt energy shows and heard salesman touting 20-30% gains from their hand-crank rack tilting gizmos!

[HX_Guy]

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.

[SunEagle]

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.

...

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.