Xantrex Technology GT3.0 owner manual Factors Affecting GT Inverter Performance, PV Array Factors

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 and specified temperature (25°C / 77°F),
	which 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	Because of several unavoidable environmental factors, you can expect your
performance	PV array to produce around 60% to 70% of its peak STC-rated output for a
	properly designed and installed PV system on a typical day.
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 (such as in winter in North America) due to the greater atmospheric air
	mass it must penetrate, reducing 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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