I use a VOM set on the low AC range across the battery to measure ripple/noise. What you really need to know is the DC output of the charger with out a load. It could be > 16 VDC.
You may want to wait on cutting down trees until you know more about the weather patterns and harvesting solar in your area. The months of Oct. > Feb. the sun is so low above the horizon cutting trees down may not make a difference. There also the problem of snow covering the panels. Adjusting...