Re: [math-fun] Solar panel calculations
Yes, I've been to that 'sunroof' web site, but it doesn't give me any details, so I haven't the slightest idea what calculations it is actually performing. Furthermore, it doesn't know the pitch of my roof, unless it is doing some clever image-matching from different satellite angles. At 08:16 AM 6/29/2020, Thomas Colthurst wrote:
I did this! Well, I and a small team. google.com/sunroof
It even does the integral over every pixel of your roof, so as to take into account shading from nearby trees and houses (as well as non-flat roofs, horizon effects, chimneys and other roof obstructions, ...).
You might also like NREL's PVWatts calculator <https://pvwatts.nrel.gov/>, which is less accurate (because it doesn't do the full ray-tracing over the roof thing) but provides more intermediate information.
-Thomas C
On Mon, Jun 29, 2020 at 10:52 AM Henry Baker <hbaker1@pipeline.com> wrote:
I'm considering putting a solar PV system on my roof, and I thought that I should be able to calculate most of the numbers myself from first principles. I have searched for so-called online 'calculators', but found that most of them are aimed at idiots.
Here's what I expected to find:
A formula giving the exact sun position throughout the year, given latitude and longitude, as well as a factor which handles the distance from the sun w.r.t. time.
Now this only provides the *input* energy.
I now need to overlay this with average *weather* data on a per-hour basis to get the expected net energy.
Finally, I need to *integrate* these data over an entire year to get the values for my own house.
There may be such an online calculator, but I haven't been able to find it yet.
It may be possible to factor the weather info out of the integration, so that I could 'correct' my location sunlight & weather data with my own lat/lon azimuth (angle of my house) and roof angle, but I'd need to see the equations to find out if this factoring is possible.
I presume that someone on this list has already done these calculations for their own home?
On Mon, Jun 29, 2020 at 11:31 AM Henry Baker <hbaker1@pipeline.com> wrote:
Yes, I've been to that 'sunroof' web site, but it doesn't give me any details, so I haven't the slightest idea what calculations it is actually performing.
Furthermore, it doesn't know the pitch of my roof, unless it is doing some clever image-matching from different satellite angles.
Well, the imagery isn't always from satellites, but yes, it builds a 3d model of every house. (We didn't build this part, it was already in Google Maps -- you can check out the 3d model of your house by going to the satellite view and then clicking the "3d" button.) -Thomas C
At 08:16 AM 6/29/2020, Thomas Colthurst wrote:
I did this! Well, I and a small team. google.com/sunroof
It even does the integral over every pixel of your roof, so as to take into account shading from nearby trees and houses (as well as non-flat roofs, horizon effects, chimneys and other roof obstructions, ...).
You might also like NREL's PVWatts calculator <https://pvwatts.nrel.gov/ , which is less accurate (because it doesn't do the full ray-tracing over the roof thing) but provides more intermediate information.
-Thomas C
On Mon, Jun 29, 2020 at 10:52 AM Henry Baker <hbaker1@pipeline.com> wrote:
I'm considering putting a solar PV system on my roof, and I thought that I should be able to calculate most of the numbers myself from first principles. I have searched for so-called online 'calculators', but found that most of them are aimed at idiots.
Here's what I expected to find:
A formula giving the exact sun position throughout the year, given latitude and longitude, as well as a factor which handles the distance from the sun w.r.t. time.
Now this only provides the *input* energy.
I now need to overlay this with average *weather* data on a per-hour basis to get the expected net energy.
Finally, I need to *integrate* these data over an entire year to get the values for my own house.
There may be such an online calculator, but I haven't been able to find it yet.
It may be possible to factor the weather info out of the integration, so that I could 'correct' my location sunlight & weather data with my own lat/lon azimuth (angle of my house) and roof angle, but I'd need to see the equations to find out if this factoring is possible.
I presume that someone on this list has already done these calculations for their own home?
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
Although it is most convenient structurally, the panels don't have to lie at the roof's angle. They can adjust the stand-offs to give them a better angle. Brent On 6/29/2020 8:29 AM, Henry Baker wrote:
Yes, I've been to that 'sunroof' web site, but it doesn't give me any details, so I haven't the slightest idea what calculations it is actually performing.
Furthermore, it doesn't know the pitch of my roof, unless it is doing some clever image-matching from different satellite angles.
At 08:16 AM 6/29/2020, Thomas Colthurst wrote:
I did this! Well, I and a small team. google.com/sunroof
It even does the integral over every pixel of your roof, so as to take into account shading from nearby trees and houses (as well as non-flat roofs, horizon effects, chimneys and other roof obstructions, ...).
You might also like NREL's PVWatts calculator <https://pvwatts.nrel.gov/>, which is less accurate (because it doesn't do the full ray-tracing over the roof thing) but provides more intermediate information.
-Thomas C
On Mon, Jun 29, 2020 at 10:52 AM Henry Baker <hbaker1@pipeline.com> wrote:
I'm considering putting a solar PV system on my roof, and I thought that I should be able to calculate most of the numbers myself from first principles. I have searched for so-called online 'calculators', but found that most of them are aimed at idiots.
Here's what I expected to find:
A formula giving the exact sun position throughout the year, given latitude and longitude, as well as a factor which handles the distance from the sun w.r.t. time.
Now this only provides the *input* energy.
I now need to overlay this with average *weather* data on a per-hour basis to get the expected net energy.
Finally, I need to *integrate* these data over an entire year to get the values for my own house.
There may be such an online calculator, but I haven't been able to find it yet.
It may be possible to factor the weather info out of the integration, so that I could 'correct' my location sunlight & weather data with my own lat/lon azimuth (angle of my house) and roof angle, but I'd need to see the equations to find out if this factoring is possible.
I presume that someone on this list has already done these calculations for their own home?
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
They also don't have to face south. Depending on what kind of storage you have (including a possible electric car), it may be worth tilting them at an angle that matches their output to your household load. That can reduce the required amount of (expensive) storage, even if you get less integrated energy delivered over the day. A similar effect may occur because of prevailing weather patterns--if it is more likely to be cloudy in the morning, maybe you want to tip the cells to optimize output in the afternoon. --R On Mon, Jun 29, 2020 at 6:36 PM Brent Meeker via math-fun < math-fun@mailman.xmission.com> wrote:
Although it is most convenient structurally, the panels don't have to lie at the roof's angle. They can adjust the stand-offs to give them a better angle.
Brent
On 6/29/2020 8:29 AM, Henry Baker wrote:
Yes, I've been to that 'sunroof' web site, but it doesn't give me any details, so I haven't the slightest idea what calculations it is actually performing.
Furthermore, it doesn't know the pitch of my roof, unless it is doing some clever image-matching from different satellite angles.
At 08:16 AM 6/29/2020, Thomas Colthurst wrote:
I did this! Well, I and a small team. google.com/sunroof
It even does the integral over every pixel of your roof, so as to take into account shading from nearby trees and houses (as well as non-flat roofs, horizon effects, chimneys and other roof obstructions, ...).
You might also like NREL's PVWatts calculator < https://pvwatts.nrel.gov/>, which is less accurate (because it doesn't do the full ray-tracing over the roof thing) but provides more intermediate information.
-Thomas C
On Mon, Jun 29, 2020 at 10:52 AM Henry Baker <hbaker1@pipeline.com> wrote:
I'm considering putting a solar PV system on my roof, and I thought that I should be able to calculate most of the numbers myself from first principles. I have searched for so-called online 'calculators', but found that most of them are aimed at idiots.
Here's what I expected to find:
A formula giving the exact sun position throughout the year, given latitude and longitude, as well as a factor which handles the distance from the sun w.r.t. time.
Now this only provides the *input* energy.
I now need to overlay this with average *weather* data on a per-hour basis to get the expected net energy.
Finally, I need to *integrate* these data over an entire year to get the values for my own house.
There may be such an online calculator, but I haven't been able to find it yet.
It may be possible to factor the weather info out of the integration, so that I could 'correct' my location sunlight & weather data with my own lat/lon azimuth (angle of my house) and roof angle, but I'd need to see the equations to find out if this factoring is possible.
I presume that someone on this list has already done these calculations for their own home?
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
_______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun
participants (4)
-
Brent Meeker -
Henry Baker -
Richard Howard -
Thomas Colthurst