Sona Linn has a Universal 25 XP. The engine charging system seems to be "standard". She has 200W of solar with a dedicated charge controller charging 270Ah house bank and separate starting battery. I noticed my cockpit volt meter reading above 15 while motoring last weekend- I checked the meter at the nav table and confirmed the same. While plugged into shore power, or under solar alone, I am between 13-14V which is normal. Any thoughts on the root cause? Voltage regulator? If so, where might I look to find it?