Solar panel angles

Re: Solar panel angles

Use PV Watts to estimate the amount of energy you can collect per month... And decide if you want more power in the summer (on grid system, best savings on power costs, and/or A/C costs).

Vs off grid system where winter has very low production and you need every kWH you can generate.

Weather can also play a factor too... if you have cloudy winters (on average), then array angle will not help or hurt you much. PV Watts is based on actual ~20 year average solar irradiation and will account for average weather/cloud conditions.

Some folks have made tilting arrays (tilt for summer/winter)--But most people seem to leave them at one angle unless they have significant snows--Then near vertical will really help keep panels clear in winter and may have have an advantage if there is a open snow covered field to the south (reflections).

PV Watts Little Rock Ark, fixed array, 1 kWatt, 0.52 off grid efficiency:

"Optimum" angle = 34.8 degrees:

"Station Identification"
"City:","Little_Rock"
"State:","Arkansas"
"Lat (deg N):", 34.73
"Long (deg W):", 92.23
"Elev (m): ", 81
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 34.8"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.4 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh) per month", "Energy Value ($)"
1, 3.78, 59, 4.37
2, 4.38, 61, 4.51
3, 5.19, 78, 5.77
4, 5.67, 79, 5.85
5, 5.89, 83, 6.14
6, 5.81, 77, 5.70
7, 5.93, 80, 5.92
8, 6.08, 83, 6.14
9, 5.41, 73, 5.40
10, 5.16, 75, 5.55
11, 3.69, 53, 3.92
12, 3.56, 55, 4.07
"Year", 5.05, 856, 63.34

Tan-invers 3/12 = 14 degrees:

"Station Identification"
"City:","Little_Rock"
"State:","Arkansas"
"Lat (deg N):", 34.73
"Long (deg W):", 92.23
"Elev (m): ", 81
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 14.0"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.4 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.10, 48, 3.55
2, 3.85, 53, 3.92
3, 4.90, 73, 5.40
4, 5.77, 81, 5.99
5, 6.32, 90, 6.66
6, 6.42, 86, 6.36
7, 6.45, 88, 6.51
8, 6.28, 86, 6.36
9, 5.23, 70, 5.18
10, 4.59, 66, 4.88
11, 3.11, 44, 3.26
12, 2.86, 43, 3.18
"Year", 4.91, 829, 61.35

Tan-ivers 12/12 = 45 degrees:

"Station Identification"
"City:","Little_Rock"
"State:","Arkansas"
"Lat (deg N):", 34.73
"Long (deg W):", 92.23
"Elev (m): ", 81
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 45.0"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 7.4 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.97, 62, 4.59
2, 4.48, 62, 4.59
3, 5.14, 77, 5.70
4, 5.41, 76, 5.62
5, 5.46, 76, 5.62
6, 5.30, 70, 5.18
7, 5.45, 73, 5.40
8, 5.75, 78, 5.77
9, 5.30, 71, 5.25
10, 5.24, 76, 5.62
11, 3.84, 55, 4.07
12, 3.76, 58, 4.29
"Year", 4.93, 835, 61.79

You decide when the power does you the most good (winter/summer) and if manual tilt is "worth it" for you -- Or just add 10-20% more panels and call it "fixed tracking" array.

-Bill