Harnessing the power of the sun used to be an expensive proposition for ranchers developing off-site watering systems.
But thanks to a frenetic expansion of production capacity by manufacturers in recent years, the price of solar-powered systems has come down, especially for photovoltaic panels.
Much of this was due to subsidies in European countries, breakneck expansion in China, and investor interest in the booming alternative energy sector worldwide. But now that the global economy has slowed down dramatically, a glut of polysilicon has led to lower prices.
“Solar has come down,” said Carl Driedger, operator of Sundog Solar, in a presentation on remote off-site watering systems during the recent Provincial Grazing Tour.
Large panels rated for 175 watts are now selling for about $900, or just over $5 per watt, down from about $10 a few years ago.
The devices for converting sunlight into electricity are also becoming more efficient, and power output per square foot has increased as the technology improves. More juice from less surface area means installations can be much smaller while still producing the same amount of electricity.
For ranchers, that means charging the batteries for electric fences and operating remote, off-grid watering systems with solar panels is becoming a more viable option.
For example, a water wagon can be parked near a water source such as a dugout, slough or creek, to keep the cattle from polluting the water and trampling the stream bank. A 175- watt panel linked to two deep-cycle batteries hooked up to provide 24 volts can run a float-switch- equipped DC sump pump capable of watering 250 head of cattle during the long days of summer, he said.
“In winter, you can cut that in half because you have to allow for less sunlight,” said Driedger.
Any battery hooked to a panel larger than 30 watts needs a regulator to prevent overcharging in bright sunlight, he added.
The latest charge controllers have a digital display that shows the voltage and amperage going in to the batteries from the panels and the amount of DC current being used. The better models feature a pulse-charging mode that kicks in at full charge and extends battery life by knocking sulphates off the battery plates.
Batteries should always be maintained as close to fully charged as possible. For a 12-volt system, that’s 12.7 volts or higher, and 25 volts or more for a 24-volt system.
“With a digital readout, you can tell that you’re there,” said Driedger. “Then your batteries will last longer. Leave the tank ‘full of gas’ and your batteries will last years.”
At Driedger’s own farm, the batteries in his watering system that runs summer and winter have lasted eight years, he added. Batteries don’t die; they are generally killed by farmers not using enough solar panels to keep them happy – never dipping below 90 per cent of peak charge. Fencers, he added, typically need 10 watts for every joule.
“Being a solar guy, I don’t want to sell a lot of batteries. That makes me look bad. I want the systems to be up and running and working good.”
Besides preventing foot rot and protecting riparian areas and water quality, off-site watering systems can also help extend water supplies, he said.
Driedger, who fences off seasonal sloughs with a single wire and then hooks up a portable watering system for his cows, is able to get every last gallon available. When it starts getting low, he wades in and uses a garden rake to clear weeds around the intake and makes a shallow hole so it can stay low enough to keep pumping water as it dries up.
“In a dry year, these systems can really help you out,” he said. “If your cows are walking the slough’s edge and punching it out, there’s more sunlight that can get in and that slough will dry up way faster.” dan[email protected]