The recirculating pump for a garden waterfall is a likely candidate for the application of solar power, and, in fact, many varieties of solar pumps are available. Incorporating one into a water garden with a waterfall doesn't take much technical know-how and can be a satisfying project for anyone who likes to work outside. A little planning will help you choose the right materials, and to size the pump and panels correctly.
Basic Waterfall Construction
A waterfall consists of three basic components: a cascade or slope down which water can fall, a reservoir to hold the water and a pump to transfer water from the reservoir to the top of the cascade. Many people dig a pond as part of the water feature, but if you'd rather focus exclusively on the waterfall, you can simply dig a sump hole. One advantage of digging a pond is that it gives you plenty of dirt to build the cascade, but you can build one with rocks or even buy a pre-formed one. The cascade and the sump or pond need liners to keep water from seeping into the ground.
Placing the Pump
If you have a pond, the pump will aerate the water while it feeds the waterfall, and that's important for keeping fish and plants healthy and the water clean. It's best to locate the pump on the side of the pond opposite the falls so that it recirculates as much water as possible. The pump also has to be close to a power source, however, and in the case of a solar pump, that means close to the panels. You should take the sunlight patterns into account when designing the pond so you can place the pump and panels advantageously.
Pumps and Panels
Solar pumps range in size from a single watt, capable of powering little more than trickle falls, to larger ones capable of transferring 250 gallons per hour or more. A large 12- or 24-volt pump needs several large solar panels to power it, while a small one may be able to run from a panel set inside a fake rock. If your pump needs a large panel, make the panel a feature of the garden rather than trying to hide it behind a bush. If you have one that tracks the sun, it will probably become a conversation piece.
If you want your waterfall feature to be independent of whether the sun is shining or not, you need to store power in one or more batteries. The arrangement can be a simple one whereby you run the pump directly from the batteries, but adding an inverter allows you to run a more powerful and less expensive alternating current pump. If the battery bank is well protected from sun and rain, the system should operate continuously and be virtually maintenance-free, except for the routine tasks of cleaning the pump filter, and tending the plants and fish.
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