By Jamie Little
28 June 2017
Inverters are a part of nearly all solar panel systems. Inverters convert DC voltage from solar panels to AC voltage for your electrical appliances and equipment.
As simple as this DC to AC conversion function appears, each inverter model and brand is different. As such there are many factors in selecting the right inverter for each situation.
In this article, we discuss one of these factors—the Minimum Voltage Window.
Inverter Minimum Voltage Window
The inverter must be sized so the input voltage from the solar panels doesn’t fall below the inverters Minimum Voltage Window. Otherwise the inverter may not turn on. There is not quite enough power to activate the inverter when the sun first peeks over the horizon in the morning. As the sun rises, the voltage in the solar array increases until there is enough voltage to activate the inverter.
Therefore, an inverter with a lower operating voltage is usually better because the inverter will come on when there is less sun (i.e. earlier in the day or when cloudy), and turn off later in the day.
The operating voltage of some popular inverters is plotted on the graph below.
Inverter Minimum Voltage Graph
Looking at the two 4000W inverters, we can see that one inverter begins to operate at nearly 150V, whilst the other at over 200V. Putting all other factors aside, we would choose the one that operates at 150W (ie the lowest minimum operating voltage). After all, we want to utilize as much sun as possible for as long as possible.
In the two 5000W inverters, and again in the two 3000W inverters, we can see the same situation.
Of course, activation voltage is only one of many factors to consider, some of which we will cover in future articles.
