Question: On the transom of my cruising sailboat you can see my solar panel array and wind generator. I have a concern over this installation, but the boatyard says I don’t need to worry.

The solar panel array and wind turbine on this cruising sailboat  are self-limiting in amperage output.

The solar panel array and wind turbine on this cruising sailboat are self-limiting in amperage output.



Both the solar panel and wind generator are installed far away from the main power distribution panel down at my navigation station belowdecks. So the wire run from the output of both the solar panel and the wind generator is fairly long, and there is no fuse or circuit breaker installed in the DC positive output cable from either of these units. The boatyard says I don’t need fuses or breakers as the devices are inherently “self-limiting” and standards state that over-current protection is not needed as long as the wiring is sized appropriately in consideration of the maximum amperage the units can generate. This line of thinking seems wrong to me, but I’m just not sure. Can you provide some guidance here?

Answer: Your boatyard service people are giving you the right answer here. ABYC Standard E-11 does offer an exception to its over-current protection requirements for devices that are self-limiting -- in other words, devices that cannot produce more current than their maximum rated output in amps. Both of the devices you show in your photo fall into that category. No matter how bright the sun or heavy the wind, neither of these devices is going to be able to produce more amperage than its peak rating. So, as long as the wiring is sized appropriately for carrying this maximum amount of current, a fuse or circuit breaker would never blow in the event of a short circuit, because of the limited current output. I hope this sets the record straight for you. Happy cruising!

 

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