Factors Affecting Sun Tie XR Performance

Temperature and

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

reduced output

temperature 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.

 

 

 

 

Note: The Sun Tie XR 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 Sun Tie XR

 

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 Sun Tie XR is designed to maximize its energy production in all of

 

the above situations using its MPPT algorithm.

Other Factors

Other factors that contribute to system losses are:

• Dust or dirt on the array

• Fog or smog

• Mismatched PV array modules, with slight inconsistencies in performance from one module to another.

• Inverter efficiency

• Wire losses

• Utility grid voltage

For additional information and technical notes concerning PV array performance, please visit our Web site at www.xantrex.com.

975-0053-01-01

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