Maintenance and Troubleshooting

Factors Affecting GT Inverter Performance

This section describes several factors that will affect the amount of power that a properly installed and operating GT Inverter can produce.

PV Array Factors

PV array ratings

PV arrays are rated at ideal factory conditions, such as specified illumination

 

(1000 W/m2), spectrum of the light (Air Mass 1.5 standard reference spectrum),

 

and specified temperature (25 °C / 77 °F), that seldom reflect real-world

 

installations. This is called the STC (Standard Test Condition) rating and is the

 

figure that appears on the PV module nameplate label.

Expected

A properly designed and installed PV system will produce less than its peak

performance

STC-rated output. Actual production depends on several unavoidable

 

environmental factors described in this section.

Temperature and

PV array temperature affects the output of the entire system. As the temperature

reduced output

on the array surface heats up, its energy output goes down. Roof-mounted arrays

 

also collect the heat generated by the roof surface (or trapped under the array) and

 

will produce less output than pole-mounted arrays, which allow greater air

 

circulation behind the panels.

 

 

 

Important: The GT Inverter will reduce its energy output to protect its electronic

 

circuits from overheating and possible damage in high heat conditions. For maximum

 

output in hot climates, mount the GT Inverter in a shaded location with good air flow.

Angle of the sun

The angle of the sun in relation to the PV array surface—the array

 

orientation—can dramatically affect the PV array output. The array energy output

 

will vary depending on the time of day and time of year as the sun’s angle in

 

relation to the array changes. Sunlight output decreases as the sun approaches the

 

horizons, due to the greater atmospheric air mass it must penetrate. This reduces

 

both the light intensity that strikes the array’s surface and spectrum of the light. In

 

general, you can expect only four to six hours of direct sunlight per day.

Partial shade

Shading of only a single module of the array will reduce the output of the entire

 

system. Such shading can be caused by something as simple as the shadow of a

 

utility wire or tree branch on part of the array’s surface. This condition, in effect,

 

acts like a weak battery in a flashlight, reducing the total output, even though the

 

other batteries are good. However, the output loss is not proportionate to shading.

 

The GT Inverter is designed to maximize its energy production in all of the above

 

situations using its MPPT algorithm.

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