Solar Panel Location with respect to the Sun

[rin67630]

No, spect sheet in the world can tell me that information with respect to my specific location. That is why I did the testing. As an engineer, I am quite capable of running the testing I needed.

But professional databases built upon many years of experience can do better, even taking mountains/hills in consideration for locations where it matters!
PVGIS calculates everything for your location: the optimum slope for maximizing summer harvesting at San Francisco is 34°

And if you had the aim of optimizing a regular year harvesting, take the option off-grid. It can even calculate the size of your needed battery.

 

[snoobler]

No, spect sheet in the world can tell me that information with respect to my specific location. That is why I did the testing. As an engineer, I am quite capable of running the testing I needed.

With some basic information, PVWatts can provide far better information than you can gather in any reasonable timeframe. If you can provide a location, array size, orientation and tilt, it will give you accurate results. I literally modeled your system in the above examples - an 1800W array in the 3 tilt configurations, and the results also reflect average weather patterns in San Fran averaged over decades of data.

I'm an engineer too, and while testing is fun, I'm CRAZY lazy. I'm going to look for the maximum reward/minimum effort solution. If I can get a near optimal answer from 15 minutes of keyboard-warrioring, I'm definitely going to take that option especially if I'm permitted to compare "what-if?" scenarios rapidly.

My posts weren't intended as a criticism of your methods. My initial post could be interpreted otherwise, and for that I apologize.

 

[Jim Burrow]

You didn't tell where you are, it was just an eventuality.
What about the other questions?

I live in the San Franciso Bay Area, a 40-mile Radius around S.F. I'm 29.5 miles due East of San Franciso, in the Livermore/Pleasington/Dublin valley. It doesn't get cold here but very hot. between 95F to 110F almost every day during June through the end of September. Here it is at the end of October and it is still in the '90s

With respect to my panels, I have no option where to place them. The only option I have is the tilt angle and that too is restrictive due to the mobile park I live in. If the panels look like a sore eye, I will be forced to take them down.

So it is very important that I can keep them as invisible as possible, but still get enough sunlight energy, which I measure in lumens and not what you see on graphs or charts which are in radians. If I know how many lumens the sun puts out, I can determine the percentage of useful energy from the sun to supply power to my controller to run the load of my house. I use lumens because I have a lumen meter, but not a meter that can measure the strength of the sun in other units.

Anyway, it looks like I'm getting a bunch of flakes for my show and tell article. I guess I better not do that again. - wow!

 

[Jim Burrow]

I would like to apologize to the whole group for my little "what I thought was a show and tell article". I didn't realize it would cause so much grief. I just wanted to tell my little story about how I found the best location and angle to place my solar Panels and how I went about doing it.

As a newbie to the Solar World on Earth (I spent 15 years on Solar in Space applications) and I guess I got too excited that I was making some progress in my understanding of building a solar system for my home and not having a lot of components in the system as the system would be visible in the Park I live in and they frown on Solar project for home and trailers. So it has to be clean looking and next.

Anyway, lesson learned - sorry again!

 

[gnubie]

You have nothing to apologise for.

 

[rin67630]

I would like to apologize to the whole group for my little "what I thought was a show and tell article". I didn't realize it would cause so much grief...

There is no need to "apologize" and I can't see any grief against you in the contributions. Maybe Germans have another culture to consider engineering, there is possibly a reason why they make good cars?
If the leading aspect of your design is to keep in line with your residential park's constraints, then this will rule and you don't need a lot of maths upfront. The databases will tell you how much you can expect to harvest with the given situation.
The open question remains: what will you do with the harvested energy? Can you feed the excess back in the grid?
Is your focus more on reducing cost, ecological considerations, or on "prepping"?
So you will mainly have too much sun most of the time anyhow, maybe you want to consider a bit of ventilation to avoid stowing heat between the panels and the carport, since you cannot tilt them enough?

P.S. the fascinating thing about solar energy, is that it is much more than " plug and play " or just piling up kilowatts. Every individual solution is different.

 

[Jim Burrow]

There is no need to "apologize" and I can't see any grief against you in the contributions. Maybe Germans have another culture to consider engineering, there is possibly a reason why they make good cars?
If the leading aspect of your design is to keep in line with your residential park's constraints, then this will rule and you don't need a lot of maths upfront. The databases will tell you how much you can expect to harvest with the given situation.
The open question remains: what will you do with the harvested energy? Can you feed the excess back in the grid?
Is your focus more on reducing cost, ecological considerations, or on "prepping"?
So you will mainly have too much sun most of the time anyhow, maybe you want to consider a bit of ventilation to avoid stowing heat between the panels and the carport, since you cannot tilt them enough?

P.S. the fascinating thing about solar energy, is that it is much more than " plug and play " or just piling up kilowatts. Every individual solution is different.

I live in the San Franciso Bay Area, a 40-mile Radius around S.F. I'm 29.5 miles due East of San Franciso, in the Livermore/Pleasington/Dublin valley. It doesn't get cold here but very hot. between 95F to 110F almost every day during June through the end of September. Here it is at the end of October and it is still in the '90s

With respect to my panels, I have no option where to place them. The only option I have is the tilt angle and that too is restrictive due to the mobile park I live in. If the panels look like a sore eye, I will be forced to take them down.

So it is very important that I can keep them as invisible as possible, but still get enough sunlight energy, which I measure in lumens and not what you see on graphs or charts which are in radians. If I know how many lumens the sun puts out, I can determine the percentage of useful energy from the sun to supply power to my controller to run the load of my house. I use lumens because I have a lumen meter, but not a meter that can measure the strength of the sun in other units.

Anyway, it looks like I'm getting a bunch of flakes for my show and tell article. I guess I better not do that again. - wow!

There is no need to "apologize" and I can't see any grief against you in the contributions. Maybe Germans have another culture to consider engineering, there is possibly a reason why they make good cars?
If the leading aspect of your design is to keep in line with your residential park's constraints, then this will rule and you don't need a lot of maths upfront. The databases will tell you how much you can expect to harvest with the given situation.
The open question remains: what will you do with the harvested energy? Can you feed the excess back in the grid?
Is your focus more on reducing cost, ecological considerations, or on "prepping"?
So you will mainly have too much sun most of the time anyhow, maybe you want to consider a bit of ventilation to avoid stowing heat between the panels and the carport, since you cannot tilt them enough?

P.S. the fascinating thing about solar energy, is that it is much more than " plug and play " or just piling up kilowatts. Every individual solution is different.

Yes, I do have two problems with respect to where and how to mount my panels. one is just what you said, the heat buildup between my metal carport roof and the solar panels. So need to work on ventilation as in the summer time, 100 plus degrees is average here.

With respect to too much solar power (energy), I may not have enough to charge my batteries after running the house all night after the sun goes down. At least according to my Solar dynamic semulator I created in Excel. But I won't be installing my system until next spring as I don't have the money right now to by the expensive battery(s).

I know I'm doing a lot of extra unessussary work, but I got the time to play around with it while it is setting on my workbench. Everything is connected expect for the panels and I'm using to junk yard 12 volt batteries. I'm using a 268 watt floor fan for my load ac load and letting everything run. - My house uses on the average 350 watts in the day and less that 150 watts after I go to bed. It takes about 30 minutes for the batteries to run the fan before they reach their low voltage point and the Utility power takes over to continue runing the load and recharging the batteries.

Anyway I'm having fun and keeping this old brain working and of the counch watching TV all day.

Anyway, that's the name of that story.

 

[45North]

Thanks for this. I find it interesting and informative!
Are you willing and able to adjust your panel angle as the optimum value changes over course of the year?
If yes, some people opt for 3 different settings over the year: spring/fall, summer, and winter. It requires more work and you have to plan for it and remember to do it but it may be worth it to you.
If not, conventional wisdom is to just opt for the winter setting (I assume SF is located around 32N?) This gives optimum power in the winter months at the expense of less-than-optimum power in the other seasons when you don't really need it anyways.

 

[Jim Burrow]

Thanks for this. I find it interesting and informative!
Are you willing and able to adjust your panel angle as the optimum value changes over course of the year?
If yes, some people opt for 3 different settings over the year: spring/fall, summer, and winter. It requires more work and you have to plan for it and remember to do it but it may be worth it to you.
If not, conventional wisdom is to just opt for the winter setting (I assume SF is located around 32N?) This gives optimum power in the winter months at the expense of less-than-optimum power in the other seasons when you don't really need it anyways.

Yes, when I get around to designing the mounting of the panels, each panel will be mounted to its own support and one end will be attached with hinges so I can adjust the angles with respect to the sun throughout the year.

I would like to make the adjustments to be automatic, but I've been retired from Electronics since 1995, and all that stuff I learned as an engineering student has long left my little brain. - so will just make the adjustment manually. But the rigging has to look nice or my wife will bitch at me.

 

[Jim Burrow]

Yes, when I get around to designing the mounting of the panels, each panel will be mounted to its own support and one end will be attached with hinges so I can adjust the angles with respect to the sun throughout the year.

I would like to make the adjustments to be automatic, but I've been retired from Electronics since 1995, and all that stuff I learned as an engineering student has long left my little brain. - so will just make the adjustment manually. But the rigging has to look nice or my wife will bitch at me.

You are right. what gets my butt, is that I only bought 6 of the 10 panels that guy had for sale for $120 each. The panels put out measured, 39vdc at 9 amps with direct sunlight at 90 degrees to the panel. These measurements are the same as what the spec sheet specified with the exception, the spec said they were 300 watts where based on my measurements, I measured 251 watts. - this is of course open-circuit voltage and Short circuit current.

However, when I connected this one panel to my all-in-one (2424lv) controller/inverter and running a load of 235 watts, The LED display showed 39 volts and pulling 9 amps, which run the load and began to charge the battery with 4 amps. - So that was a big surprise.

But yes, I will do like you said, adjust the panels for option angle for all year around. Then if I need to adjust them, I will still have that option throughout the year.

 

[45North]

I agree.
I am at a similar lattitude to the OP and the winter is when you need the power most. Here the winter is 8 hours of dayilght and 14 in summer.
Summer takes care of itself with greater radiation and more of it.

That said, the difference or gain in having panels tilted to winter from a more suitable summer orientation is not a lot on real terms. You are trying to improve the output of a greatly reduced output from the start. there are not huge gains to be made in actual KWH. For me the difference between my flattish roof and going to the trouble, expense and risk ( wind) of setting the panels up for winter just isn't worth it.
Where possible, throw up an extra panel of the same size and you are miles ahead.

If someone IS going to tilt their panels, then Winter is the orientation to go for and don't even worry about the rest. Spring and autumn you are unlikely to need heating or cooling so your power consumption will be less anyway.

I was wondering if there is any opportunity for the OP to set up some panels in his yard on a ground mount to get some extra and better optomised power from them?

So, they say for optimum year-round use to set the panels at an angle equal to your latitude. In my case that would be 45 deg - ie half-way between horizontal and vertical.
So, if you live north of me (like most northern Europeans - actually anyone north of Lyon France!) set them steeper than 45.
If you live south of me, like most Americans, set them more horizontal.

 

[chrisski]

When I see the panels provide less than ideal energy because of placement, but those are the cards you've been dealt, I start wondering if putting a couple more panels on it into the backyard, kind of like extending the carport, would be practical.

 

[Jim Burrow]

So, they say for optimum year-round use to set the panels at an angle equal to your latitude. In my case that would be 45 deg - ie half-way between horizontal and vertical.
So, if you live north of me (like most northern Europeans - actually anyone north of Lyon France!) set them steeper than 45.
If you live south of me, like most Americans, set them more horizontal.

I wish I could do that without restrictions. 45 degrees tilt would put my panels 90 degrees to the sun at noon or the highest point in the sky and that would be great. Unfortunately, if I go much higher than 11 degrees in tilt, I might get in trouble with the Mobil park I live in and will be forced to remove them as an eyesore. - pure b.s. but I have to live within their rules. Actually, they don't want any solar in the park at all and it is totally forbidden to mount them to our roofs.

Actually, I live in a modular/manufactured home, and these homes although they are not trailers, have no attic, and drilling into the roof will go right through the ceiling. - Try to explain that to the wife!

 

[Jim Burrow]

I wish I could do that without restrictions. 45 degrees tilt would put my panels 90 degrees to the sun at noon or the highest point in the sky and that would be great. Unfortunately, if I go much higher than 11 degrees in tilt, I might get in trouble with the Mobil park I live in and will be forced to remove them as an eyesore. - pure b.s. but I have to live within their rules. Actually, they don't want any solar in the park at all and it is totally forbidden to mount them to our roofs.

Actually, I live in a modular/manufactured home, and these homes although they are not trailers, have no attic, and drilling into the roof will go right through the ceiling. - Try to explain that to the wife!

Point taken. My town latitude is 37.6819 degrees N and 121.7685 degrees W. Unfortunate, I have a very little wiggle room/latitude (not referring to latitude and longitude) to play with. The only place I can put my 6 panels is on my carport roof and would be facing almost due North and titled down 11 degrees from a horizontal plane or 70 degrees angle from the sun. At that angle, I only get 35% of the solar energy to power my panels. So that is why I need to title one end up so more of the panel gets sun light.

Tilting my panels by only 22 degrees from the present negative tilt (or 11 degrees tilt above horizontal pain) will give me 100% sunlight in "lumen" for this time of year (October) for 6 hours without getting in trouble with park rules that I live in that frown on Solar panels and go out of their way to force the owner to take them down. - So I'm playing with A.H. for management.

I think it is hard for most people to imagine the restrictions I'm dealing with as most people don't have many issues where they can place their panels and orientation.

This little report of mine has generated some interesting discussions. And I hope it has given people several resources to go to for their situation.

 

[Jim Burrow]

I literally could not live in a place like that. I'd end up in jail from beating some interfering busy body over the head with their overbearing rules and regulations.



In this day and age of save the planet and greenwashing, that is surprising. I'll bet one one anonymous letter to the local paper or TV station about the body corporate that is against doing the right thing for future generations and not supporting clean Unreliable energy ( insert other green crap for sensationalism) would soon turn that policy around if they were embarrassed by it.

You might want to see if it is in the conditions or caveats of the estate or if they are just power tripping, pardon the pun.



There are adhesives now that would do the job just fine.

Again, what about a ground mount in the back yard?

Don't have space as that is the wife's gardening area. But I like your idea, they just might be power tripping, It's only hearsay about the solar, I should check the park rules and as you say, if I get too much bull out of them, I bet the newspaper would like a good story.

 

[rin67630]

I think it is hard for most people to imagine the restrictions I'm dealing with...

USA... the land of the ultimate freedom?
Must be hard to live there, with such crazy (p)resident(s)

 

[Jim Burrow]

USA... the land of the ultimate freedom?
Must be hard to live there, with such crazy (p)resident(s)

we have only had one that I consider pure crazy although there have been several I didn't like.

 

[rin67630]

we have only had one that I consider pure crazy although there have been several I didn't like.

The plural was for "residents."

 

[rin67630]

Các nhà sản xuất đánh giá các tấm pin quang điện của họ dựa trên công suất đầu ra DC ở mức bức xạ 1000 W / m2 (mặt trời đầy đủ) và nhiệt độ của tấm pin là 25oC để giúp bạn mua sản phẩm của họ. Một bảng điều khiển PV 12 volt tiêu chuẩn sẽ tạo ra điện áp đầu cuối tối đa khoảng 20 volt trong điều kiện ánh sáng mặt trời đầy đủ mà không cần tải được kết nối. Tuy nhiên trong thế giới thực, các tấm pin mặt trời quang điện hoạt động dưới các cài đặt lý tưởng này dẫn đến công suất đầu ra thấp hơn nhiều so với mức công suất đầu ra tối đa có thể có của tấm PV.

I will not contradict you...

 

[ianganderton]

Các nhà sản xuất đánh giá các tấm pin quang điện của họ dựa trên công suất đầu ra DC ở mức bức xạ 1000 W / m2 (mặt trời đầy đủ) và nhiệt độ của tấm pin là 25oC để giúp bạn mua sản phẩm của họ. Một bảng điều khiển PV 12 volt tiêu chuẩn sẽ tạo ra điện áp đầu cuối tối đa khoảng 20 volt trong điều kiện ánh sáng mặt trời đầy đủ mà không cần tải được kết nối. Tuy nhiên trong thế giới thực, các tấm pin mặt trời quang điện hoạt động dưới các cài đặt lý tưởng này dẫn đến công suất đầu ra thấp hơn nhiều so với mức công suất đầu ra tối đa có thể có của tấm PV.

Vietnamese to English using google translate

Manufacturers rate their photovoltaic panels based on their DC output power at a radiation level of 1000 W / m2 (full sun) and the panel temperature of 25oC to help you buy their products. . A standard 12 volt PV panel will produce a maximum terminal voltage of about 20 volts in full sunlight without the need for a connected load. However in the real world, photovoltaic solar panels operating under these ideal settings result in an output power much lower than the maximum possible output power level of PV panels.