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Solar Water Pumping

"Let it Shine" - the 6,000-year story of Solar Energy

Have had an enjoyable summer, playing with various kits we have in prototype, and working on several projects at once.

25-watt solar panel with 12-volt pump in barrel

25-watt solar panel with 12-volt pump in barrel

One of the most interesting to me was employing solar water-pumping in our garden.

I had recently discovered that one can buy on eBay a 25-watt solar panel for $50.00 US – delivered to my door, for free! When I bought my first 25-watt panel, 20 years ago, it had me cost $225.00.

We’ve been using the older panel with a 12-volt bilge pump to pump water from a shallow well down to barrels in the garden.

I joined the two barrels with a U-shaped length of irrigation hose filled with water and ends immersed upside-down into both barrels, to their bottoms, creating a siphon between the two barrels. This results in a bank of water barrels that will draw down and fill at the same level approximately.

Bilge pumps are commonly available in hardware stores in the boating section, and are of good quality and inexpensive, around $25.00. Alternately, one can go shopping on-line for a 12-volt pump from AliExpress…$12.00, and again, free delivery. (I recognize these pumps – they’ve been around a long time, are of good quality, and handily fit down through a bung hole.)

When I first set this solar water-pumping system up in the garden, and was walking around with a hose spouting water, all driven by sunlight, I felt a flush of good power; and wondered for a moment how I’d feel if a poor farmer in Africa, using this for the first time.

We live on an island in the rain-shadow between Vancouver Island and the mainland. It gets hot and dry here in the summertime, and watering the garden is necessary nearly every day. For years we watered with the hand-watering can shown; about a barrel’s worth daily in the peak of summer.

Well, wandering around with a hose wasn’t much better than wandering around with a watering can…but we had a plan. A month or two earlier we had gone to an irrigation system workshop, and learned that an inexpensive way of making a low-pressure drip irrigation system was to use 1/2 inch black irrigation pipe (sold in 100 foot rolls).

Instead of buying the irrigation fittings sold along with this hose, one can cut off small sleeves of the tubing to cover drilled holes.

You will still need to get some 1/2-inch poly tee’s, couplers, and end plugs…and lots of #6 hose clamps….to lay out the lines.

As for tools, two come in handy – one to tighten the hose clamps, and one to cut tubing. For a hose clamp tightener, best to get a screw-driver handled socket that fits the hex heads of the hose clamps.

tubing cutter useful for cutting tubing and slicing short segments

Tubing cutter

tubing cutter, cutting 1-1/2 inch segment of 1/2-inch black poly irrigation hose

tubing cutter, cutting 1-1/2 inch segment

slicing a segment of tubing to act as a hole cover

slicing a segment of tubing

sliced segment of tubing to act as hole cover, a sleeve.

sliced segment of tubing

Tubing cutters are of various designs. This one, inexpensive, not only cuts the tubing where necessary (when laying out lines for each of the vegetable rows in the garden), but also handily and safely slices 1-1/2-inch (4 cm) segments of tubing to act as hole covers, slipped as sleeves over the irrigation hose wherever a hole has been made.

The water pressure generated by a 12-volt pump is enough to fill the hose and have water seeping from every hole. The water spreads to the edges of the sleeves, and drips directly to the ground where you want it.

water seeping from sleeve covering hole in 1/2-inch black poly irrigation hose

water seeping from sleeve covering hole

1/2-inch poly tee with 1/2-inch black irrigation hose and hose clamps

1/2-inch poly tee

I was surprised to find that even when I shut the pump off, the barrels drained, siphoned.

I eventually installed valves at the base of the barrels, so as to be able to direct water to various sections of the garden, or to use the hose, or to shut off lines to prevent siphoning.

One notable result of using this irrigation system was the plants – they reached for the sky with their leaves!

"Let it Shine" - the 6,000-year story of Solar Energy