Solar Panel Layouts

[dave01978]

Guys, I am so thankful to this site, as I have found a ton of information and able to tell total BS from sales people based on what I have learned the last month or so seriously researching the topic. Anyone know typically how they come up with the roof layouts and how many panels fit. I do not have an actual roof measurment however I have 3 different layouts and number of panels that fit the front side facing south all are Hanwha Q.Peak Duo BLK-G5 I have quotes that use 315W,320W, 325W all appear to show the same size on the spec sheet online.
Proposal one shows 5 high by 2 wide. then 3 high, then 1 high (based on slant of roof) 14 panels
Proposal two shows 3 high by 6 wide then 2 high then 1 high 21 panels
Proposal three shows 3 high by 5 wide then 2 high, then 1 high 18 panels
I am just supprised how different everyone shows the panel layouts especially with the same sized panels
Just looking for feedback, based on how actual plans come back based on preliminary designs? I am almost close to choosing a company, but want to get feedback based on designs of how panels typically fit based on the before hand measurements, as I don't want to go back and find out that the quote with the most panels in front is way inflated becuase in reality it can hold 16 panels.

Based on a quick google earth math i came up with the square portion of 18 Wide x 16 high (i am asuming the 16 does not account for rise) then at the top it has an angle that goes out about another 9ft) so I can almost see it possibly having room up there, I am not sure what the setback requirements are in my area, as I tried searching but really go no where.

Also google project sunroof shows 1519 hours of usable sunlight with 1,180sq feet available for solar panels.
Just wanted to get feedback from people who have seen layout differences like this. I also uploaded the screenshot from google project sunroof (not sure if that helps or not)
Thanks
Dave

[J.P.M.]

In your research and so based on your annual load and how much of it you want to offset, how big of a system are you considering ?

[Markyrocks69]

Here's an idea. Get a ladder and a tape measure. Get up there and measure what you got up there. Should be pretty much idiot proof to figure out after the fact.

[littleharbor]

Here's an idea. Get a ladder and a tape measure. Get up there and measure what you got up there. Should be pretty much idiot proof to figure out after the fact.

That and the fact that you can use Portrait or Landscape orientation, or a combination if necessary.

[dave01978]

In your research and so based on your annual load and how much of it you want to offset, how big of a system are you considering ?

my annual usage is about 12,700kWh, i am ideally looking at near 100% since right now the incentives are prertty good, so roughly a 10kW system. After running the numbers based on a loan from Clean Energy CU outside the solar installer, it will be between $10-12K after all is said and done with the interest in the loan and possibly slightly higher depdning on how the Illinois SREC's work as far as tax on that as I have heard different answers.

Markyrocks69, I am not that worried about the actual measurement, i just thought it was interesting that 3 different companies came out with 3 different # of panels on the south facing. All being Hanwha Q Cells (that from what I can tell are all the same physical size.

[Ampster]

.......... i am ideally looking at near 100% since right now the incentives are prertty good, so roughly a 10kW system. After running the numbers based on a loan from Clean Energy CU outside the solar installer, it will be between $10-12K after all is said and done with the interest in the loan and possibly slightly higher depdning on how the Illinois SREC's work as far as tax on that as I have heard different answers.
.........

A 10kW systemn for $ 10-12k is less than $1.50 per kW. I assume that is after incentives.

[ButchDeal]

A 10kW systemn for $ 10-12k is less than $1.50 per kW. I assume that is after incentives.

less than $1.50/w (not kW).

[J.P.M.]

my annual usage is about 12,700kWh, i am ideally looking at near 100% since right now the incentives are prertty good, so roughly a 10kW system. After running the numbers based on a loan from Clean Energy CU outside the solar installer, it will be between $10-12K after all is said and done with the interest in the loan and possibly slightly higher depdning on how the Illinois SREC's work as far as tax on that as I have heard different answers.

Markyrocks69, I am not that worried about the actual measurement, i just thought it was interesting that 3 different companies came out with 3 different # of panels on the south facing. All being Hanwha Q Cells (that from what I can tell are all the same physical size.

Thank you.
- As others suggest, get up on the roof and measure. Leave room for access to all the panels for maint. You will probably never fully cover a roof. SWAG is often 60-80 % coverage or less until a firm layout is done. Between shading, building codes and access for maint./cleaning, you'll never get 100 m^2 of panels on 100 m^2 of roof 100 m^2 of roof - maybe ~ 70 m^2 or so.
- Remember: Peddlers/vendors make money putting product on your roof, not necessarily getting the best design on your roof or the most cost effective system per kWh produced. Reputable vendors will do OK, but you're usually on your own for getting a system layout that's serviceable and avoids most shadowing.
- While on your roof measuring, look around and figure out how shadows from adjacent structures/trees and roof protrusions will affect panel placement. Remember, the sun moves north to south and back again once per year. That will make shadow effects/on output different for different times of the year.
- Have you modeled potential annual output using PVWatts ?
- Annual output per installed STC kW will be approx. equal for most any panel.
- Bigger concern is how panel layout may be affected by local building/fire codes for panel placement restrictions on a roof.
- Do you have net metering available ?
- What's your annual electric bill at this time ?
- What's your zip ?
- Are you planning a DIY system ? If you buy shartp and know what you're doing 1$/installed STC W is possible but getting that low from a vendor for a turnkey grid tied system may be hard to achieve. Equally difficult will be finding a vendor who will install what you buy on your own if that is on your mind.

[Markyrocks69]

I think the OP needs to ask this question to the reps responsible for the quotes/,plans ect. I'd put my money on "different strokes for different folks" but I'm sure that string size/limits, ease of installation ect probably have alot to do with the differences between the estimates ect.

[dave01978]

Thank you.
- As others suggest, get up on the roof and measure. Leave room for access to all the panels for maint. You will probably never fully cover a roof. SWAG is often 60-80 % coverage or less until a firm layout is done. Between shading, building codes and access for maint./cleaning, you'll never get 100 m^2 of panels on 100 m^2 of roof 100 m^2 of roof - maybe ~ 70 m^2 or so.
- Remember: Peddlers/vendors make money putting product on your roof, not necessarily getting the best design on your roof or the most cost effective system per kWh produced. Reputable vendors will do OK, but you're usually on your own for getting a system layout that's serviceable and avoids most shadowing.
- While on your roof measuring, look around and figure out how shadows from adjacent structures/trees and roof protrusions will affect panel placement. Remember, the sun moves north to south and back again once per year. That will make shadow effects/on output different for different times of the year.
- Have you modeled potential annual output using PVWatts ?
- Annual output per installed STC kW will be approx. equal for most any panel.
- Bigger concern is how panel layout may be affected by local building/fire codes for panel placement restrictions on a roof.
- Do you have net metering available ?
- What's your annual electric bill at this time ?
- What's your zip ?
- Are you planning a DIY system ? If you buy shartp and know what you're doing 1$/installed STC W is possible but getting that low from a vendor for a turnkey grid tied system may be hard to achieve. Equally difficult will be finding a vendor who will install what you buy on your own if that is on your mind.

of the 3 I think could possibly add another row, 1 is good, and 1 i think has 1 row to many.
Yes, I have played around with PVWatts quite a bit, and learned quite a bit.
Annual electric is $1609.88 with a total usage of 12737kWh
Yes net metering is available, and there are 2 options, I will likely go with option #2
1) a 1-1 credit
2) an hourly rate, with a credit of the cost of the hourly pricing, and usage from the grid at the cost of the hourly pricing (i am currently on the hourly pricing and save about 10%, and think this will work out better since the cost is cheaper over night then during the day while the panels are producing. Also this is a $ credit, which can go towards any item on the bill, so if I cut back I can actually credit on the meter, and customer charge portions possibly (preliminary system is designed at 101% offset)
I totally hear about others putting panels where ever, as I had a couple with panels on the north side, instead of using the smaller section of East / West
Zipcode 60586
I am having the work done, as I hear and read it can be a headache getting some of the electrical part, that needs a contractor, as well as the SREC's in Illinois is a pain, and I really don't want to be monkeying around on my roof either.
The overall system size is 10,080W DC

I certainly appreciate all that i have learned here on this site.
Dave

[J.P.M.]

of the 3 I think could possibly add another row, 1 is good, and 1 i think has 1 row to many.
Yes, I have played around with PVWatts quite a bit, and learned quite a bit.
Annual electric is $1609.88 with a total usage of 12737kWh
Yes net metering is available, and there are 2 options, I will likely go with option #2
1) a 1-1 credit
2) an hourly rate, with a credit of the cost of the hourly pricing, and usage from the grid at the cost of the hourly pricing (i am currently on the hourly pricing and save about 10%, and think this will work out better since the cost is cheaper over night then during the day while the panels are producing. Also this is a $ credit, which can go towards any item on the bill, so if I cut back I can actually credit on the meter, and customer charge portions possibly (preliminary system is designed at 101% offset)
I totally hear about others putting panels where ever, as I had a couple with panels on the north side, instead of using the smaller section of East / West
Zipcode 60586
I am having the work done, as I hear and read it can be a headache getting some of the electrical part, that needs a contractor, as well as the SREC's in Illinois is a pain, and I really don't want to be monkeying around on my roof either.
The overall system size is 10,080W DC

I certainly appreciate all that i have learned here on this site.
Dave

Thank you. Off topic: I was in Orland Park and Aurora seeing friends and visiting a niece and her family in Naperville a couple of weeks ago after visiting the Friendly Confines for 3 days and watching the Cubbies beat the Padres 2 out of 3. Lots of friends in Chicagoland.

Back on topics:
- $1,610/yr/12,737 kWh/yr = ~ $0.1264/kWh. Believe it or not, that's pretty cheap. At the going rate of ~ $3.00/STC W for PV, you'll most likely have a long time to breakeven pretty much regardless of the method you use to determine cost effectiveness/ROI/payback. It often takes a per kWh rate of something > $0.20 or so to get a net positive cash flow in a reasonable time frame (say ~ <7-10 yrs. or so). The numbers vary a lot but $0.12/kWh is a tough nut to crack w/turnkey PV prices as they are. Your results may vary.
- Be sure of that credit from the POCO, particularly the per kWh credit amount. I don't know what your POCO does, but a very common method is to credit excess production at something like the wholesale rate of the POCO pays for power. That's often about 1/3 or less than the retail rate the customers pay. Most potential users who bother to investigate POCO pricing and net metering policies assume the excess generation is paid at retail rates. That's often/most of the time an incorrect assumption and rarely the case.
- You will have to deal with snow removal. Like it or not, it's a big PITA in places where it snows. Snow can also create other problems and the more snow, the more often and more problematic the snow consequences become. Another reason to be careful with plans for panel layout. Member Bruce Row lives NW of you and is probably the resident expect with respect to arrays and snow. Maybe he'll have time to comment.
- I take it to mean "having the work done" to mean a turnkey system from a PV vendor. If you have not done so already, consider using only local vendors who are licensed electrical contractors and have sold PV for 5 + yrs. or more. Negotiate tough but fair and remember it's bad to pay too much, but worse to pay too little. Buying on low initial price is the errand of a fool and will cost more in the long run.
- Using that $3.00/ STC W turnkey price est.: 10 STC kW * $3.00/ STC kW *0.70 = $21,000 net system cost after tax credit. The simple moron payback method : $21,000 net system cost/$1,610 /yr. = 13 yrs. "payback". Other costing methods taking lots of stuff into account like rate inflation, alternative investment comparison, and other stuff will probably make the financial picture even less rosy.
- A 30 deg. tilt, 108 deg. az. orientation will probably get you something like 1,400+ kWh/yr. per installed STC kW. Don't know your roof layout or shading, but after accounting for such things and snow blocking, A 10 kW system may well be limited to that 12,700 kWh/yr.

Take what you want of the above. Scrap the rest.

[bcroe]

- Be sure of that credit from the POCO, particularly the per kWh credit amount. I don't know what your POCO does, but a very common method is to credit excess production at something like the wholesale rate of the POCO pays for power. That's often about 1/3 or less than the retail rate the customers pay. Most potential users who bother to investigate POCO pricing and net metering policies assume the excess generation is paid at retail rates. That's often/most of the time an incorrect assumption and rarely the case.

- You will have to deal with snow removal. Like it or not, it's a big PITA in places where it snows. Snow can also create other problems and the more snow, the more often and more problematic the snow consequences become. Another reason to be careful with plans for panel layout. Member Bruce Row lives NW of you and is probably the resident expect with respect to arrays and snow. Maybe he'll have time to comment.

Unfortunately my snow blocking avoidance methods, though demonstrated effective, are
very difficult to apply to a roof mounted array. I see roof mounting as writing off much of
winter production in these parts. But then, our snow months here (zip 61084) are so cloudy,
that is not such a big loss. One Dec we went 27 days in a row without seeing the sun.

6 years ago IL ComEd had 4 PV solar plans, partly based on size. I am not sure what is in
place now, but I just trade KWH 1 for 1, no money exchanged. Naperville had their own
power distribution system/billing, perhaps they used to generate it too like others I know of.
BTL ran the first North American cell phone trial there long ago.
Bruce Roe

[Markyrocks69]

- $1,610/yr/12,737 kWh/yr = ~ $0.1264/kWh. Believe it or not, that's pretty cheap. At the going rate of ~ $3.00/STC W for PV, you'll most likely have a long time to breakeven pretty much regardless of the method you use to determine cost effectiveness/ROI/payback.

This was basically my use case scenario. Electric is so cheap in my area, 10-12c kwh ect, that paying a company even 2$ a watt would have made my roi like 15-20 years or something. In that scenario you're basically just swapping the electric bill for a loan payment and I wasn't prepared to go down that route. In the end my 20kw system after incentives ect I'm in the ballpark of 40-50c a watt. But in the scenario where the system total would have been 2.50$ a watt it's just not feasible. I'm in pa so idk if what the srec market is like I havehaveeven looked into it recently.

[J.P.M.]

Unfortunately my snow blocking avoidance methods, though demonstrated effective, are
very difficult to apply to a roof mounted array.
Bruce Roe

But you're still the Emperor of the North with respect to the snow - PV interface.

[ButchDeal]

This was basically my use case scenario. Electric is so cheap in my area, 10-12c kwh ect, that paying a company even 2$ a watt would have made my roi like 15-20 years or something. In that scenario you're basically just swapping the electric bill for a loan payment and I wasn't prepared to go down that route. In the end my 20kw system after incentives ect I'm in the ballpark of 40-50c a watt. But in the scenario where the system total would have been 2.50$ a watt it's just not feasible. I'm in pa so idk if what the srec market is like I havehaveeven looked into it recently.

you keep mixing before incentive and after incentive $/w

if you are interested in SRECs (which I don't know you you are not already since you seem very fixated on ROI) then check out: https://srectrade.com/

I think it is $32 but was $12 just last year You should generated enough to pay off the registration and meter fees quickly and then all profit. ( not much but still something).