panel orientating in maine

nyarelathodep

Anyone have a good reference for panel orientating or know of a good Android app dedicated to such a purpose? I'm in Western Maine (sumner) , on a North facing slope, but with lots of clear South facing exposure. Was figuring on more West facing for catching mid to late day charging.

BB.

Re: panel orientating in maine

PV Watts is pretty simple to use and do "what if" comparisons:

http://rredc.nrel.gov/solar/calculators/pvwatts/version1/

Solar Electricity Handbook has more cities (and not as many options):

http://solarelectricityhandbook.com/solar-irradiance.html

Both seem to be pretty accurate and consistent with each other.

-Bill

jtdiesel65

Re: panel orientating in maine

You'll get the best power at mid day esp in winter. I personally wouldn't put the panels any more than 10 degrees out of mid day. You probably already know, but solar south will be different from magnetic south. IIRC here it's ~16 degrees different.

nyarelathodep

Re: panel orientating in maine

What tool is used to determine solar South? What do installers typically utilize?

jtdiesel65

Re: panel orientating in maine

You can look it up or use a map

http://www.ngdc.noaa.gov/geomag-web/#declination
http://www.ngdc.noaa.gov/geomag/img/DeclinationMap_US.png
http://www.ngdc.noaa.gov/geomag/declination.shtml

Organic Farmer

Re: panel orientating in maine

nyarelathodep wrote: »

What tool is used to determine solar South? What do installers typically utilize?

I did it using two methods.

First, I used a Boy Scout compass and subtracted the standard magnetic deviation for this region.

Secondly, I made a sun-dial. After I calibrated it [mark exactly where each hour mark is] the line through 11am - 1pm is an exact solar East-West line. The same with the line through 10am - 2pm, and 9am - 3pm.

I did these methods when we were making the foundation for our house. We wanted our house to be exactly aligned, for Passive Solar Thermal gain.

I am in the Southern half of Maine, about 20 miles North of Bangor. The Southern wall of our home is large windows. In January-February we get enough Solar Thermal gain, that our home does not dip below 50F inside. Even when it is -20F outside. Granted 50F is not very comfy, by itself, but at least it shows that the physics works. The amount of heat we need to introduce is a lot less.

Our Photo-Voltaic array is also constructed exactly East-West. So our panels face directly 'Solar' South.

We want to generate as much power as possible during the window of sunlight available to us, from early sun-rise to sun-set. During the early hours, and the later hours the suns rays are off at an angle. Let the MPPT circuits do their magic. That is what they were designed for.

zoneblue

Re: panel orientating in maine

Organic Farmer wrote: »

I did it using two methods.

First, I used a Boy Scout compass and subtracted the standard magnetic deviation for this region.

this works fine.

Secondly, I made a sun-dial. After I calibrated it [mark exactly where each hour mark is] the line through 11am - 1pm is an exact solar East-West line. The same with the line through 10am - 2pm, and 9am - 3pm.

Creative. Both these methods will get you in the right part of the sky. For the record, solar noon has an annual variance, caused by procession of the perihelion. The effect is that if you plot the path of solar noon in the sky for a year, it looks like a figure 8, and old fashioned sun dials often depict this, and have a correction table to compensate for this 'equation of time'.

Here, right now for instance solar noon occurs at 1307. Thats 1 hour for DST, and 7mins for EQT.

I did these methods when we were making the foundation for our house. We wanted our house to be exactly aligned, for Passive Solar Thermal gain.

I am in the Southern half of Maine, about 20 miles North of Bangor. The Southern wall of our home is large windows. In January-February we get enough Solar Thermal gain, that our home does not dip below 50F inside. Even when it is -20F outside. Granted 50F is not very comfy, by itself, but at least it shows that the physics works. The amount of heat we need to introduce is a lot less.

Our Photo-Voltaic array is also constructed exactly East-West. So our panels face directly 'Solar' South.

We want to generate as much power as possible during the window of sunlight available to us, from early sun-rise to sun-set. During the early hours, and the later hours the suns rays are off at an angle. Let the MPPT circuits do their magic. That is what they were designed for.