Can I run a bilge pump off a solar panel for prospecting?

You can, but not the way most people try it first. A 12 volt bilge pump wired straight to a panel runs only while the panel is in full sun and pointed right. A passing cloud, a low sun or your own shadow drops the voltage and the pump slows or stops, and a recirculating setup stops moving water mid-run.

The setup that works

Panel → MPPT controller → battery → pump. The battery is the buffer. It holds the pump at a steady voltage while the panel charges whatever it can, and it keeps the pump going after the sun drops behind the ridge.

• The controller. A SmartSolar MPPT 100/30 charges at up to 30 amps, takes up to 440 watts of panel on a 12 volt battery and up to 100 volts on the panel side. Mount it in the shade; it gives full output only up to 40°C.
• The panel. One 200 watt panel such as the Renogy 200 W ShadowFlux is the starting point. Add a second if the battery is lower each evening than the one before.
• The battery. Size it to the pump. Rule lists its 1500 GPH pump at 4.8 amps at 13.6 volts, so six hours of pumping is about 29 amp-hours. A Peak Power Pack in the 40 amp-hour size covers that alone. If a drywasher shares the battery, step up to a 100 amp-hour Lithium SuperPack.

Two details that catch people

• The Peak Power Pack has its own solar input, so for a pump-only setup you can skip the separate controller. That input accepts 11 to 25 volts and limits current to 7 amps, so check that the open-circuit voltage on the panel's label is under 25 volts before you connect it.
• Fuse the pump at its maker's rating, 10 amps for the Rule 1500 and 7.5 for the 1100, and put a MIDI fuse on the main lead at the battery. A pinched wire on a rocky wash is a short waiting to happen, and lithium will feed it hard.

Keep the battery in the shade too. In the desert the limit is heat, not cold. Our full guide has the wire-gauge table for long runs from the battery to the pump.