Ask Sail: Underperforming Solar

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This corroded fuse was having a major impact on performance (left); Cleaning it up again was a piece of cake (right).


Q: I have a pair of solar panels on my aft arch feeding to a solar voltage regulator and then feeding my bank of three AGM house batteries. All was well for the last two winters, but now when the panels are putting out 15-plus volts the regulator begins to shuts down the charging current. The batteries are only three years old and test fine with a load checker. Any ideas?

— Tom Delong, Marin, CA


Solar panels with no load or regulator naturally put out around 19-plus volts. When connected to a battery, they will begin to charge it at around 13.8-14.2 volts to the point the regulator begins to reduce charging current. A common problem can be fuses in holders that develop resistance in the wiring. With just a few milliohms of current resistance, the panel voltage can go high, to the point where the regulator begins to limit charging current after sensing too much voltage. Clean all fuses and terminal strip connections from the panels and enjoy more charging current at a more normal voltage level

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