Using solar heat and power for barns and grain drying

Which solar options suit a barn?

Barns have large, simple roofs and steady loads, which is a good fit for photovoltaic panels. Ventilation fans, lighting, water pumps, milking and cooling equipment, and shop tools can all draw from an array on the roof, with the grid as backup. The planning steps are covered in solar panels on a farm, and the difference between systems tied to the grid and those off it is in grid-tied versus off-grid solar.

The alternative is solar heat. Solar air collectors warm fresh air before it enters a barn or a dryer, cutting the load on the heater. They are simpler than liquid systems and work well for ventilation air. Our guide to solar air heating explains how they work and the guide on solar thermal versus PV shows when each suits.

How much energy does grain drying take?

A physics estimate shows the scale. Drying 100 tonnes of grain from 18 percent to 14 percent moisture removes roughly 4,650 kilograms of water. Evaporating a kilogram takes about 0.63 kWh, so the theoretical minimum is close to 2,900 kWh. Real dryers use considerably more, because hot exhaust air carries heat away. These are rough numbers with simplifying assumptions, and a dryer's data sheet and your fuel records give the true figures.

Two conclusions follow. First, drying is a heat problem, so solar thermal fits it better than electric panels. Second, the energy is moderate per tonne but large over a harvest, which is why dryers burn a lot of propane or natural gas in a short period.

Why does the harvest season limit solar drying?

On the Prairies, harvest and drying often run from late summer into October or later. Days are shorter, the sun is lower and nights are cold and damp. A solar collector contributes less heat then than in July, and a damp, cloudy week can bring it near zero. Drying needs a steady supply of warm, dry air, so solar usually works as a preheater that reduces fuel use, not as the only source. Natural-air drying with a fan and modest added heat depends on the weather too.

Orientation and tilt matter at low sun angles, as covered in collector orientation for heating. Fall output is the number to ask installers about, not the annual one. Solar panels in winter covers the related snow and low-light questions for electric systems.

What should you check before investing?

• Fuel records. How much propane or gas does drying use, and when? Solar savings are measured against that.
• Roof or ground space. A collector for a dryer should sit close to the intake. Look at the roof's structure and orientation.
• Collector type. Simple glazed or perforated air collectors differ in cost and performance. For liquid systems the main collector types are compared in evacuated tube versus flat plate.
• Expected output in season. Ask for kilowatt-hours of heat per season at your location, with assumptions stated.
• Permits and insurance. Roof work and heating equipment may need approval, and your insurer should know.
• Funding. Check programs for on-farm energy projects, covered in agricultural solar grants in Canada, before buying.

What does Drake Landing add to this?

Drake Landing Solar Community in Okotoks, Alberta, faced a similar mismatch between summer sun and winter heat demand and solved it with storage: 800 flat-plate collectors fed tanks and then a field of 144 boreholes that held heat for the heating season. The solar collection page describes the arrays. A grain dryer cannot justify seasonal storage, so the farm answer is different: use solar for the loads that line up with the sun, which in many barns means summer cooling, ventilation and daytime electric loads, and treat drying as a partial saving. The community was wound down from about 2020, a reminder to budget for upkeep of any solar equipment.

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