does higher array voltage make more power in the morning?
It is often said that higher array voltage means the solar setup will make power earlier in the morning. Let’s test it.
the data
I’ve observed this phenomenon with different panels, panel arrangements, and controllers. Today I finally made a screenshot so we could talk about it here. This particular setup is 750w at 20v nominal (30.3Vmp) on a Victron 150/45 controller.
This is the timeline:
- 0610 - array voltage (Vpanel) starts to come up from 0v. Harvest is unmeasurable.
- 0649 - Vpanel has risen to 14.4v but harvest is still unmeasurable.
- 0712 - Vpanel has risen to 24v and harvest becomes measurable at 5w (0.7% of rated). This would ~14.4v for 12v nominal panels.
- 0720 - the array has reached Vmp and harvest jumps to 25w (5.5% of rated).
- 0753 - the array has been at normal voltage for a half-hour and has just risen to 75w (10% of rated).
analysis
In this example The 20v array starts making measurable power 23 minutes earlier than a 12v array would.
Actual harvest during those 23 minutes is tiny: less than 1% of the array’s rated wattage. With a 200w array it would be a an extra 0.19Wh harvested each morning.1
If there were thunderstorms and it was very dark all day it would be a whopping gain of 11.2Wh.2
conclusion
So, yes, a higher voltage array will make more power in low-light conditions. After all, 0.19Wh is more than 0.0Wh. In practice the difference is so small it could be a rounding error.
There are valid reasons to run higher-voltage arrays but IMO increased low-light harvest is not one of them.