A Saskatchewan company has developed a solar powered grain dryer that puts the power of the sun to work on the farm.
The Solar Assist Dryer from Peacock Industries looks like an air mattress that can be pegged to the ground or mounted to the side of a grain bin. It is made of two layers of polyethylene tarpaulin material. A clear layer allows the sun’s rays through and air to flow evenly over a black layer that absorbs the heat.
Cool air is channelled from the bin into a solar collection chamber where it is heated and dried by the sun. The air is then pulled back into the grain though the aeration fan, improving drying time.
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The air is channelled through a sleeve wrapped around the nozzle between the fan and the bin.
Peacock Industries president Neil Wagner said at peak sunlight on a Nov-ember day, the dryer produces 60,000 to 75,000 BTUs.
A “good, sunny day” in September would produce 150,000 to 175,000 BTU per hour for approximately seven hours per day. The comparable cost of natural gas is $1.63 per hour.
“So anytime it is worth your while having an aeration fan running, it is worth having this thing in there to try to warm the air,” said Wagner of Hague, Sask.
Riverhurst, Sask., area farmer Rodney Kent used the dryer several days this fall. He said the harnessed heat sped drying time, but he wasn’t sure by how much.
“I’m certainly not disappointed with it. It was doing what it was supposed to do. The air coming out of it was warmer than the ambient air so it was definitely heating some. It would be nice to see if there was research done to see what effect it has,” he said.
“I think it is effective. I’m just really not sure what the payback time would be because that’s what the bottom line is. So that will be an ongoing evaluation.”
Wagner said the amount of drying the system provides varies by crop, moisture level, temperature and cloud cover. For example, flax seed is harder to dry because its oil holds moisture more than a dry seed like wheat or corn, which flows air better. The system’s effectiveness can only be measured in general, he said.
“The best analogy that I can come up with is it takes a 20 degree day and turns it into a 30 degree day as far as it’s drying power,” said Wagner. He said the system can reduce humidity by 15 percent or more.
A Texas customer bought the collector to dry walnut wood. It takes a long time for moisture to come out of hardwood and kiln drying often causes splitting and damage, said Wagner.
“So they want to dry it a little slower. The solar dryer is kind of perfect because it dissipates the heat slowly and evenly throughout the course of the day. There is no actual extra energy other than airflow through the building, which they were pumping through the building anyway. They were just heating a certain amount of it now. It was a very gentle way of drying the wood.”
The solar energy can also be used to heat buildings. Wagner said one customer placed the collector on top of an unheated garage and installed a thermostatically controlled fan. When there was enough heat inside the solar panel the fan clicked on and blew the warm air inside the garage.
“Even on 40 below days it would light up once in a while and blow a bit of warm air inside the garage just to take the chill off of unheated situations,” said Wagner.
Most of the dryers go to American customers. Annual sales vary from year to year depending on conditions, but the solar collector has been growing in popularity, particularly among the environmentally conscious, he said.
“The green aspect of this makes it more and more attractive as social consciousness rises toward fossil fuel use,” Wagner said.
“The most efficient solar collectors in the world in the desert are running at 39 to 40 percent of collection efficiency of the sun’s rays and they go to the most intense sun area they can find to do that. This one collects about 18 to 20 percent but it’s biggest thing is it’s about as inexpensive a unit as you will ever find for solar collection.”
Some solar collectors use water or oil to collect heat, but the Peacock model uses only air, making it inexpensive. The system comes in two sizes: the 12 by 24 foot unit is $479 and the 12 by 48 foot unit costs $699.
