Go Power GP-SB-PWM-10 10 Amp Digital Solar Controller, LCD

The Go Power GP-SB-PWM-10 is a simple, honest little solar charge controller for boats running a modest panel setup. It sits between your solar panel and your battery, taking the raw output off the array and feeding your bank a clean, regulated charge. Rated at 10 amps, it's sized for the kind of small solar install most cruisers actually run: a panel or two keeping the house battery topped up while you're on the hook.

What you get here is pulse width modulation, or PWM, charging. The controller reads your battery voltage and pulses the incoming solar current to bring the bank up without cooking it. It's the tried-and-true approach that's kept boat batteries healthy for decades. PWM isn't the most efficient technology out there for big arrays, but for a 10 amp system on a daysailer, a tender, or a weekender it's exactly the right tool. Simple, reliable, and easy to wire in.

The front panel is a digital LCD, so you're not guessing about what your solar is doing. You can see battery voltage and charge status at a glance. There's also a built-in USB charge port right on the unit, which is handy for topping off a phone, a handheld GPS, or a headlamp straight off the solar without dragging out an inverter. That's a nice touch on a boat where every amp counts and outlets are scarce.

Go Power built four layers of protection into this one, and on a boat that matters. You get reverse-polarity protection on the battery side and on the solar array side, so a miswired terminal won't smoke the controller. There's over-temperature protection that backs the charge off if the unit gets too hot, and over-current protection that guards against a fault pulling more than the controller can handle. None of that is glamorous, but it's the stuff that saves you a ruined afternoon and a replacement part.

A few things we've learned about installing these. Mount it somewhere dry. The LCD and the electronics don't love a damp, salty locker, so a spot inside the cabin on a dry bulkhead is your friend. Give it a little breathing room too. These controllers shed heat, and if you bury one flat against a bulkhead in a hot engine space it can hit its over-temp cutout and stop charging right when you need it. A few inches of clearance below and around it keeps air moving. And when you land your ring terminals, torque them down properly and fuse the battery leg. Loose connections are the number one reason a controller like this acts up.

Battery chemistry is worth a thought before you buy. This controller uses fixed charge setpoints tuned for standard flooded lead-acid batteries, and that's where it shines. If you're running AGM or a lithium bank with specific voltage requirements, take a close look at whether those setpoints line up with what your battery wants. For a classic flooded house battery on a small cruiser, it's a great match.

Sizing is straightforward. At 10 amps this controller is built for small arrays, think a single panel in the 20 to 100 watt range on a 12 volt system. That covers most tenders, daysailers, and a lot of 22 to 27 foot powerboats keeping a battery alive between weekends. If you're planning a big multi-panel bank for a passagemaker or a liveaboard, you'll want to step up to a larger controller. But for keeping the lights on and the bilge pump ready on a smaller boat, the GP-SB-PWM-10 does the job without fuss and without a complicated setup.

Wiring it up is about as simple as solar gets. Panel leads to the solar terminals, battery leads to the battery terminals, and you're charging. There's no app to fool with, no menu to learn, and nothing to reconfigure every season. For a boater who just wants a solar panel to quietly keep the battery alive, that kind of set-it-and-forget-it simplicity is exactly the point.