Based on historical 01581 data, solar panels that are tilted towards the equator at an angle equal to the latitude will produce the maximum solar energy output in 01581.
The region associated with 01581 has an average monthly Global Horizontal Irradiance (GHI) of 3.82 kilowatt hours per square meter per day (kWh/m2/day), which is approximately 1% greater than the average monthly Direct Normal Irradiance (DNI) of 3.77 kWh/m2/day. 
Solar installations in 01581 that are always titled at the latitude of Westborough (Average Tilt at Latitude or ATaL) average 4.53 kWh/m2/day, or about 19% greater than the average monthly GHI of 3.82 kWh/m2/day and approximately 20% greater than the average monthly DNI of 3.77 kWh/m2/day. 
Global Horizontal Irradiance: The total amount of solar radiation that is received per unit area by a surface that is always positioned in a horizontal manner.
Direct Normal Irradiance (DNI)
Direct Normal Irradiance: The total amount of solar radiation received per unit area by a surface that is always perpendicular to the sun rays that come in a straight line from the direction of the sun at its current position in the sky.
Average Tilt at Latitude (ATaL)
Average Tilt at Latitude: The total amount of solar radiation received per unit area by a surface that is tilted toward the equator at an angle equal to the current latitude. ATaL will often produce the optimum energy output.
Solar Radiation Levels in 01581
Solar Radiation Data in 01581
See the chart below for monthly solar radiation levels in 01581.
* Amounts listed in kWh/m2/day (kilowatt hours per square meter per day)
Solar Radiation Analysis for 01581
Sorry, it is not possible to complete our solar radiation analysis for 01581 at this time.
Historical solar radiation data for 01581 is not currently available.
Please check back later.
Solar Power Comparison: 01581 vs. the U.S.
Solar Power Levels in 01581
Sorry, solar radiation data for 01581 is not currently available. Please try again later.
Solar Power: 01581 vs. the U.S.
Below is a month-by-month comparison of how average 01581 solar radiation levels compare to average levels in a city with historcially high levels (NV) and a city with historically low levels (WA). 
→ k/m/d = kWh/m2/day = kilowatt hours per square meter per day.
→ Values listed as 0 (zero) are not available (N/A).