Guesstimating production

[Jdcarrol]

I'm making great progress on installing roof top solar and found that I can actually include a few more panels in the plan. I'm trying to guestimate how much electricity the system will generate to see if I should buy a few more. Can someone with more knowledge than me affirm my understanding and approach?

Phoenix AZ Average Peak Sun Hours: 6.57
Panels: 30
Pannel Wattage: 440W
Panel placement: 15 on pitched roof facing east. 15 on pitched roof facing west

So I use the following equation to guestimate production: ((6.57*440*(15+15)*0.5)/1000 = 43.36Kwh

I divide everything by half because half the pannels face west, half the pannels face east......Generally speaking, is this math sound?

 

[sunshine_eggo]

It's really hard to guesstimate panels that are not optimally tilted south. Your method isn't bad.

You can simulate one of the arrays via the PVWatts link in my signature for your location, power and orientation. The East will likely perform better than the West by a bit due to clearer skies and cooler PV cells.

 

[x98myers7]

yep, more accurately...

step 1:

SunCalc sun position- und sun phases calculator

Application for determining the course of the sun at a desired time and place with interactive map.

www.suncalc.org

get your azimuth

step 2:
plug in arrays, azimuth and angles 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