Samlex 85W Solar Expansion Kit SRV-EXP-85-KIT

The Samlex SRV-EXP-85-KIT does one job, and it does it well. It adds 85 watts of rigid-panel solar to a charging system you've already got. That's why it's called an expansion kit. If you started with a Samlex solar setup and found yourself short on amps by the end of a long weekend off the grid, this is the clean way to grow it. You're not tearing anything out. You're bolting one more panel to the roof and tying it into the array you already trust.

Here's what shows up when you open the box: the 85-watt rigid solar panel, the connecting wires, a set of branch and multi-contact connectors, and the mounting brackets and hardware to get it down solid. What's not in the box is a charge controller, and that's on purpose. An expansion kit assumes you've already got a controller sized for your system. You wire this panel in alongside your existing one, and the same controller handles the extra input. Before you buy, make sure your controller has the headroom to take another 85 watts. Most do, but it's a two-minute check that saves a headache later.

The panel itself is a rigid unit, 21.54 inches wide by 47.76 inches tall, and just 1.38 inches thick. It puts out 85 watts at 22.1 volts, which works out to roughly 3.8 amps in full sun. That 22.1-volt nominal figure matters when you're picking or confirming a controller. An MPPT controller will make the most of that higher panel voltage, pulling more usable charge into your batteries than an older PWM unit would, especially when the sun's low or the panel's partly shaded.

Mounting is bracket-style, which is the standard approach for a fixed roof install on an RV, a trailer, or a boat's hardtop. The included stainless hardware gets you started. One tip from experience: anything that lives on a roof and takes road or water vibration all day wants a dab of threadlocker or a set of locknuts on those bracket bolts. Factory hardware is fine, but vibration is patient, and you don't want to be chasing a loose panel down the highway. Seal your mounting penetrations properly and you'll never think about it again.

Wiring is where the branch connectors earn their keep. They let you tie this panel into your existing array in parallel without cutting into your main runs. The multi-contact connectors are the industry-standard weatherproof type, so once they're seated they shrug off rain and spray. If you're running in a salt environment, a little dielectric grease on the contacts is cheap insurance against corrosion down the line.

A word on real-world output, because rated watts and delivered watts are never quite the same. You'll see the full 85 watts on a cold, clear day with the sun square on the panel. In summer heat, at a lazy roof angle, expect something more like 55 to 65 watts of real charging. That's normal for any fixed flat-mounted panel and it's not a knock on this one. If you want to claw some of that back, a tilt mount aimed at the sun makes a real difference in the shoulder seasons.

So who's this for? Anyone with an existing Samlex solar system who wants more daily charge without redesigning the whole setup. Weekend campers who keep running the battery down. Full-timers adding capacity a panel at a time. Boaters topping off a house bank at anchor. It's a straightforward, honest piece of gear from a company that's been building power conversion equipment for a long time. And who's it not for? If you don't have a solar system yet, you want a complete starter kit with a controller instead. This one assumes you've already got the foundation and just need more panel.