Solar Panel Snow Loss Calculator (Australia)

How to use this calculator

Enter six values to estimate annual energy lost to snow cover and the winter monthly breakdown (June–September in Australia):

1. System size (kW) — total nameplate. The Australian residential average is 6.6–8.0 kWp.
2. Peak sun hours per day — Australian capital city averages range 4.0 (Hobart) to 5.5 (Darwin). Snowy Mountains sites average 4.3–4.8.
3. System efficiency (%) — derate. PVWatts and the Clean Energy Council default to 78%.
4. Panel tilt (°) — roof pitch for most installs. Australian default roof pitch is 22.5 degrees; alpine homes often have 30–40 degree roofs.
5. Annual snowfall (cm) — total winter season. The Bureau of Meteorology operates snow stations at Thredbo Top Station, Spencers Creek and Mt Hotham.
6. Electricity rate (A$/kWh) — current tariff. Most retailers charge 30–38 c/kWh peak.

Snow loss in the Australian context

Australia is the second-driest inhabited continent and most of its solar capacity (over 95%) is installed in zones that never see snow. Snow loss is a niche concern for installations in:

• NSW Snowy Mountains — Thredbo, Perisher, Charlotte Pass, Jindabyne
• Victorian Alps — Falls Creek, Mt Hotham, Mt Buller, Dinner Plain
• Australian Capital Territory — Mt Ginini and the Brindabella Range above 1,400 m
• Tasmanian Central Highlands and West Coast — Lake St Clair, Cradle Mountain, Mt Wellington summit

Below 700 m elevation in NSW and 900 m in Victoria, snow is too transient to cause measurable annual losses. Hobart sees occasional snow at sea level but never enough to derate annual PV production.

Australian snow loss benchmarks

Sunwiz, Solar Analytics and CEC field data combined with the Marion 2013 NREL snow-loss model give these annual loss ranges for a typical 25-degree roof install:

For ground mounts at 40 degrees+ tilt, halve these. Low-tilt commercial roofs (10–15 degrees) lose roughly twice as much.

The Marion 2013 NREL model adapted for Australian alpine conditions

Bill Marion’s 2013 NREL paper Measured and Modeled Photovoltaic System Energy Losses from Snow for Colorado and Wisconsin Locations is the standard reference. Three findings translate directly to Australian alpine installations:

1. Sliding dominates clearing. Australian alpine snow is generally drier and lower-density than Colorado snow, so it slides at lower panel tilts (25–30 degrees is sufficient).
2. Albedo bounce partially offsets direct losses. Snow-covered ground at Perisher and Falls Creek reaches albedo 0.85, returning 4–7% diffuse irradiance to the array even when direct sunlight is blocked.
3. Winter share of annual energy at AU latitudes is small. June–August accounts for only 13–15% of annual production at Snowy Mountains latitude (versus 18% at Colorado latitude), so the same percentage panel obstruction produces less annual loss.

What reduces snow loss in Australian alpine zones

Use a 30–40 degree tilt

Most Australian roof tilts of 22.5 degrees are too shallow for heavy alpine snow. If you’re building a new house at Thredbo or Falls Creek, specify a 35-degree roof pitch on the north face. Existing 22.5-degree roofs benefit from tilted racking that adds 10–15 degrees.

Specify alpine racking certified to AS/NZS 1170.3

Australian Standard AS/NZS 1170.3 covers snow and ice loading on structures. Standard CEC-approved racking is certified to a snow load of 1.5 kPa, which is sufficient for sub-alpine sites. Sites above 1,200 m elevation in NSW or 1,400 m in Vic require 2.5–3.5 kPa rated racking — Sunlock Alpine and Clenergy SnowMount are the common options.

Choose frameless glass-glass panels

REC Alpha Pure, SunPower Maxeon 6, LG NeON H and Trina Vertex S+ glass-glass modules shed snow within an hour of the sun emerging. Worth specifying for ski-lodge installations and high-altitude rural properties.

Skip aggressive snow clearing

Holiday-home owners frequently ask about heated panel surfaces or motorised snow rakes. The economics rarely work: an alpine 6.6 kW array losing 5% to snow loses about 450 kWh/year worth A$160 at 35 c/kWh. Heated surface kits cost A$3,000–6,000 and consume their own electricity. Better to absorb the loss.

Common mistakes

• Assuming Snowy Mountains installations are unviable. A 6.6 kW Thredbo array produces 8,500–9,000 kWh annually after snow losses — still excellent ROI under the AEMC small-scale technology certificate scheme.
• Using standard CEC racking above 1,200 m elevation. Alpine snow loads can exceed standard certification. Always specify AS/NZS 1170.3 alpine-rated mounts.
• Forgetting STC-eligible zones extend across snow country. Small-scale Technology Certificates are zone-based but don’t penalise alpine installations — the SRES calculation already incorporates regional yield.
• Ignoring shading from snow on adjacent objects. Snow accumulation on chimneys, vents and adjacent buildings can create new shading not present in summer site surveys.

Sources

• Clean Energy Council — Solar PV Design Guidelines
• NREL — Measured and Modeled PV Energy Losses from Snow — Marion 2013 reference model
• Bureau of Meteorology Snow Reports — Snowy Mountains and Tasmanian highland snowfall data
• AS/NZS 1170.3 — Australian/NZ snow and ice structural load standard
• Sunwiz Australian Solar Performance Survey
• Solar Analytics PV Performance Benchmarking