Inverter start-up and noise levels
As soon as enough light falls on the panels in the morning, the inverter will start up. The exact moment of starting up depends on various weather related factors. Also, there will be differences between systems. A system with panels oriented east could start up slightly earlier compared to a system oriented west. Obviously, the brand and model of the inverter and the number and type of panels can also make a small difference.
Every inverter has a specific start-up voltage. As soon as there is daylight, solar panels immediately start producing a fairly high voltage. With enough panels in a string, the start-up voltage will then also directly be reached. During the design phase of systems, the minimum number of panels to reach this is of course always taken into account.
It is not necessary to have direct sunlight on the panels. Also in diffuse light (for example on a cloudy day), solar panels will produce a sufficient voltage to start up the inverter. However, under rare circumstances it could happen that the inverter will not start up, for example on a very dark winter day. This is no reason to worry, on such a day very little energy would be produced anyway. For the production estimates very advanced weather models are used which take this into account as well.
When an inverter starts up and operates it will make some noise. The noise levels are however so low that they shouldn’t cause any hindrance. Additionally, inverters are installed in rooms that are not commonly used, like the attic or a technical room.
The maximum sound levels of the inverters currently offered by Sungevity are shown in the table below.
These sound levels are comparable to soft whispering on the lower side to a refrigerator on the higher side.
A switched-on inverter