Automatic dual-MPPT stringing

HelioScope has two different options for defining string lengths. The set from temperature method automatically calculates the minimum and maximum string lengths using ASHRAE weather data. According to the temperature of the site and components selected, HelioScope will give a suggested range of string lengths. If you don't want the range provided, the set manually method allows you to manually adjust the minimum and maximum string lengths as needed. You can set the minimum and maximum string lengths to the same length if you only want a single string length for your wiring zone. Toggle between these methods using the text link at the bottom of the stringing section.

String Lengths & ASHRAE Calculations

String lengths can be affected by many factors of a design, but the most critical are the components used, and the local temperature extremes. When considering the components used, we determine the effect of temperature on voltage for the modules and how that can affect the capacity of the inverter. HelioScope has gathered ASHRAE temperature data from across the world to provide the maximum and minimum values for sites. By using this local temperature data, HelioScope can automatically offer recommendations for string sizing that will not exceed the MPP range of your inverter in both hot and cold conditions.

If you do not want to use the recommendations, however, you do not need to use them. You can still set a string length outside of the MPP range of the inverter, but be aware that this may result in clipping for your system.

What if the ASHRAE data in my design isn't the correct city?

While we have collected a substantial amount of ASHRAE temperature data, some locations may not have their own ASHRAE data. In this case, we will take the nearest site to the location of the project and use that for the recommendation. If you prefer to use your own string length calculation you can select the "set manually" option to input the correct string limits. 

Additional Stringing Options

By clicking show details, you can display additional stringing options:

• Conductor Size: like other conductors, you can choose the string conductor size. See additional details here: Optimize conductor size
• Along Racking/Up and Down Racking: this stringing strategy is intended for use with Frames. It allows you to choose whether strings follow Frames horizontally or vertically