Victron Solar Generation

Sakura came equipped with 2X100w Victron SPM100-12/3a solar panels and a Victron 100/30 MPPT controller, charging an aged 4X100AH AGM house bank.  These panels have kept the house bank charged while the boat has been on the hard and during my periodic refit visits over the past year.   
 

In May 2024, I finally decided to download the Victron app and see what the panels were doing, and was surprised to find that the two were typically generating a total of less than 100W.  50-85w typically, at 16-18VDC.    This at mid-day, in the tropics.   When connected individually, both panels behaved similarly, with each generating 25-40W.   

Am not sure where the problem lies.  

• Is this normal with these panels?  
• Are the panels failing? (identically?)
• Could tired batteries be the cause?
• Could there be an issue with the MPPT controller?
• Could the controller have been programmed in such a way as to cause this?

Many thanks!

Responses to the forgoing are:

• Panel is shaded, mostly by the wind generator.  This will significantly reduce output.
• Connections should be checked for corrosion.
• MPPT controller may be more efficient if panels are connected in series.
• A seperate controller for each panel is ideal.
• Bifacial or better quality panels (CIGS) would help.
• panels will rarely be at 90deg to the sun, significantly reducing efficiency.

A good first strategy might be to:

1. clean up the connections 
2. remove the wind generator 
3. re-wire panels in series.   
4. measure output with each change. 

Based on my experience with a 175watt installation on Windstar, I find it hard to believe that the panels are functioning as they should, but we'll see.

Panel dimensions are 47X21.5", frame is 1.375"h

mounting frames are 23 3/16" o/c