Optimal tilt angel

[MI Solar Guy]

I wanna run this past everyone here who knows waaaay more then me.

Now my optimal tilt is 32.6⁰ for all seasons buuut, I'm thinking I can fanaggle this to compensate for over paneling in the summer and better tilt in the winter.

My thought is, in the summer we know solar works and works good. But if I position my panels more for the winter months and leave them there, over paneling would be perfect for summer and add more power in winter.

I came up with 40.1⁰ as the optimal tilt.

Obviously I won't over volt my SCC (150volts) but if I use the calculation I posted, I would go over on watts and amps.

I'm going to use 3s3p of the panels I posted a pic of.

Any advice is greatly appreciated.

 

[MI Solar Guy]

Sorry I wasn't clear in my first post. What I'm looking to do is use less then optimal in the summer and have it close to optimal in the winter.

 

[yabert]

Only 40° in Michigan?
Snow is it a problem?

As you wrote, in summer we have plenty of sun to charge battery and power everything. And in winter, the few hours of good sun are precious and it's normally in nov. dec. and jan we would need the max output from each panel.
I'm in south of Quebec, Canada, my panel are mount 45° and if I had the possibility I would mount them at 60° to help cleaning snow for those thought winter months with low sun.

 

[MI Solar Guy]

Only 40° in Michigan?
Snow is it a problem?

As you wrote, in summer we have plenty of sun to charge battery and power everything. And in winter, the few hours of good sun are precious and it's normally in nov. dec. and jan we would need the max output from each panel.
I'm in south of Quebec, Canada, my panel are mount 45° and if I had the possibility I would mount them at 60° to help cleaning snow for those thought winter months with low sun.

I mean, I'm in Detroit MI so snow piles up a bit lol. I'm thinking 40⁰ because my all season optimal is 32.6 but from October to February it's 37⁰ to 47⁰. I have a ground mount and kids so keeping them clean is easy lol. If there's a hole in my logic please let me know.

 

[Danke]

I mean, I'm in Detroit MI so snow piles up a bit lol. I'm thinking 40⁰ because my all season optimal is 32.6 but from October to February it's 37⁰ to 47⁰. I have a ground mount and kids so keeping them clean is easy lol. If there's a hole in my logic please let me know.

Winter solstice December 22-23 for Detroit is 24.3° Sun angle.

So tilt would be 65.7°.

Optimum Tilt of Solar Panels

 

[yabert]

If you can sacrifice some output in summer to have best output in winter, the optimal panel angle should be around 60°

That way, the annual production will be lower, but you will have more output during critical months (nov, dec, jan).
Write differently, that way, month after month your output will be more even.

 

[SeaGal]

I mean, I'm in Detroit MI so snow piles up a bit lol. I'm thinking 40⁰ because my all season optimal is 32.6 but from October to February it's 37⁰ to 47⁰. I have a ground mount and kids so keeping them clean is easy lol. If there's a hole in my logic please let me know.

If you have ground mount, could you make it manually adjustable for two different tilts, one for summer one for winter? Or even 3 settings (summer, winter and spring+autumn/fall) ? Just a thought as you only have 6 small panels?

BTW: Nice to see some panels that are not made in China

 

[MI Solar Guy]

If you have ground mount, could you make it manually adjustable for two different tilts, one for summer one for winter? Or even 3 settings (summer, winter and spring+autumn/fall) ? Just a thought as you only have 6 small panels?

BTW: Nice to see some panels that are not made in China

I really appreciate all the replys and I can definitely adjust per season like you mentioned. I'm trying to avoid that as much as possible but I'm not against doing that either.

 

[MI Solar Guy]

So in Detroit, my optimal angle from horizontal is 60⁰ for Nov, Dec and Jan?

 

[JoeHam]

I have a ground mount and kids so keeping them clean is easy lol. If there's a hole in my logic please let me know.

Logic fault: kids don’t want to do whatever their parents want them to do ?.

Seriously though, optimizing for winter and having excess in summer anyway makes perfect sense.

 

[OffGridForGood]

you can run the numbers for your location on PV Watts and I doubt there is 10% difference in annual PV using the steeper (winter) angle all year around.
I am north of 49 in the NW of Ontario, I tilt up Nov 1st and down April 1st, using 60-degrees (actually a bit more) for winter -mostly to clear snow, but also to gain the bit of PV I can during those poor solar months. Snow clears WAY better at 60-degree angle.
My panels are at 30-degrees now and stay there until end of October.
If I didn't have snow, I am not sure I would ever move them.

 

[MI Solar Guy]

Logic fault: kids don’t want to do whatever their parents want them to do ?.

Seriously though, optimizing for winter and having excess in summer anyway makes perfect sense.

Fortunately I tied their tablets and Nintendo to the panels working so they hustle lmao ?

I've never seen a 9 and 12 yr old grab a broom so fast ?

 

[MI Solar Guy]

you can run the numbers for your location on PV Watts and I doubt there is 10% difference in annual PV using the steeper (winter) angle all year around.
I am north of 49 in the NW of Ontario, I tilt up Nov 1st and down April 1st, using 60-degrees (actually a bit more) for winter -mostly to clear snow, but also to gain the bit of PV I can during those poor solar months. Snow clears WAY better at 60-degree angle.
My panels are at 30-degrees now and stay there until end of October.
If I didn't have snow, I am not sure I would ever move them.

Its looking like I'll use a fixed mount at 55⁰. From what I'm learning Here through all the experience of everyone. Right now I only have 6 panels at 40⁰ and I hit a float charge by 1 pm. My bat-tree bank is 6 200amp AGM wired 2s 3p for 24v 600 amp.

Now that the sun is out longer, everything works great. I wanna build it so it works in dec/jan.

 

[Bluedog225]

I don’t need as much power in the winter.

 

[MI Solar Guy]

I don’t need as much power in the winter.

Definitely, I hear that. And our power consumption goes does in the winter too.
The problem is, the sun goes down fast then too.

What I'm trying to build is a seemless system. I don't want my wife or kids to wonder is today is the day we can't watch TV or cook dinner, ect...

I wanna fill my battery bank even on bad days too

 

[OffGridForGood]

I wanna fill my battery bank even on bad days too

Check PV Watts, plug in your data for angle and PV and check what you get in Nov and Dec, I think you're going to be great until end of October, then not so much until middle/late January. I know up where I am November is the worst month, mostly due to cloudy days. These can last 4-5 days in a row and I gain very very little PV during those days. Using a TOU I can charge up on grid "off-peak rate" at night and know the batteries are going to be full for the next day. Unlike you guys, I actually use more electric during winter, not less, so sad to have peak demand at min available time of year!
If you want to make your system Family-Friendly, you may want to be able to tilt up for winter to help clear snow. Maybe 60-70 degrees if possible, just a suggestion. A good push broom and a long handle (paint roller extension type works) can be handy.

 

[MI Solar Guy]

Actually you bring up a great point! The only way I can see my PV watts is through my SCC. I know I don't need to explain this but I will in case a newbie is reading, my SCC only tells me what it's allowing to come in. So at solar noon and my bank is at a float charge I'm being told I'm getting 400ish watts ?. What tool would you recommend for true PV wattage measurement?

 

[OffGridForGood]

I think you're misunderstanding, I mean the PVWatts calculator from NREL see link here:

PVWatts

Estimates the energy production and cost of energy of grid-connected photovoltaic (PV) energy systems throughout the world. It allows homeowners, small building owners, installers and manufacturers to easily develop estimates of the performance of potential PV installations

pvwatts.nrel.gov

 

[OffGridForGood]

Type in your general location, and PV Watts pulls up the closest weather data monitoring station.
{this is international, I pulled data for my own area, for a member in Johannisburg South Africa, and for a guy in Birmingham UK}
Next input the data for your own set-up, either what you have, or what you would like to "test" and see the results.
You can print these, or name and save the files.
You can go back and change say the tilt of the panel angle, and see what change you get for each month.
I played with this and found the "ideal angle" for each month, and made a chart of the max PV by month, but comparing it to one set angle made very little difference over the entire year.
The main difference (in my location) was what I could get for maximizing Nov- Jan. Using just my49-degree latitude for the tilt angle, for my 9.68kW array compared to tilting up to 72 degrees resulted in 65kW more energy collection, but also nearly self-clearing for snow. At very steep tilt angles, a tiny bit of wind and there will be no snow on the panels. I have been playing with an idea to attach an old 1/4-sheet vibratory sander to the back of the solar rack next winter, and put it on a timer lol, never know, it just might work.

You can use PV Watts to test ideas, like, "if I put 2kW of PV on my West roof at 18.43 degrees, what power collection can I expect to gain" -plug all the data into the calculator and let it spit out values, takes only a minute and you don't need to buy anything to see likely results.

 

[Techie007]

Now my optimal tilt is 32.6⁰ for all seasons buuut, I'm thinking I can fanaggle this to compensate for over paneling in the summer and better tilt in the winter.

My thought is, in the summer we know solar works and works good. But if I position my panels more for the winter months and leave them there, over paneling would be perfect for summer and add more power in winter.

Any advice is greatly appreciated.

Overall, I think this is an interesting (and potentially good) idea. However, there is one factor I have not seen mentioned yet. Diffuse, overcast weather light comes from directly overhead, regardless of the angle of the sun. By tilting your panels sharply to the south, you will significantly increase your sunny winter output and reduce snow buildup on your panels, while decreasing your overcast weather output at all times of the year. You can test this anytime it's overcast—lay a solar panel flat on the ground facing the sky, and then gradually lift it up on one end to tilt it. As the tilt increases, the output will decrease, regardless of the time of year. This difference can be significant, up to around 50% depending on how steeply you're tilting the panels. On a grid-tie system, one would ignore this as the overall number of kWh produced during overcast weather is insignificant. But if you're off-grid, potentially halving your production during overcast weather could be a problem if there were a series of these days in a row. Something to think about!