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It goes without saying that throughout the year the amount of sunlight in any given day is going to vary. The time of year and weather will have a strong influence on daily sunshine. Looking at the average amount of peak sunshine hours in a day during an entire year stretch is a valuable exercise when trying to determine the amount and type of solar panels you need to install to power your business or your home. 5.2 peak sun hours means that in Petersburg on average there are 5.2 hours a day where the sun is strong enough for solar panels to harness its energy. This number is less than the amount of total sunlight hours in a day because there are times during the day (ex. sunrise and sunset) where the sun is not strong enough to benefit solar panels.

Sunlight hits the earth directly at the equator. This is why the equator has a latitude of zero degrees. The latitude of Petersburg is 40.0. Knowing the latitude of Petersburg can help you plan for your solar panel setup, as the larger the latitude the more variance you will see throughout the year for total daily sunlight hours.

A tracking mount will increase the average peak sun hours for a solar power system. Think about a panel that is tracking the sun in the sky vs a panel that is fixed and not moving: you will see a higher efficiency ratio of productions. A 1-axis mount will track the sun from East to West from sunrise to sunset and move on a single axis of rotation. A 2-axis mount will track the Sun from East to West the same as a 1-axis mount would, but it will also track the angle of the sun in the sky as it slowly varies season to season. A 2-axis mount is more necessary in high latitude regions where the angle of the sun in the sky changes dramatically between each equinox.

Weather is one of the major culprits that will cause inconsistent total peak sun hours for any given day. The sunrise and sunset will always be predictable every day, but the weather is hard to predict and cloud coverage can greatly diminish the efficiency of a solar power system on any given day. On the bright side, a location that is known to have cloudy weather a majority of the year could have unexpectedly more sunny days, so it can go both ways.

By taking the latitude of Petersburg one can get a close estimate of the amount of average peak sun hours per day for the geographical area. It varies with technology and the type of solar panel mount you use, but for a fixed mount solar panel in Petersburg one can expect close to 5.2 average peak sun hours per day. With a 1-axis tracking mount you would get 6.1 hours per day, and 6.5 hours per day with a 2-axis tracking mount that tracks the sun everywhere in the sky.