What Size Solar System Do I Need for My Alberta Home? (2026 Calculator)

TL;DR. The Alberta sizing formula is kW = annual kWh ÷ (1,200 × orientation × tilt × shading), rounded up to the nearest 0.5 kW. A typical Edmonton home using 8,500 kWh/year on a south-facing 30° roof needs roughly 7.5 kW (15 LONGi Hi-MO 7 500 W panels, ~36 m² of roof, ~$21,000 cash installed). The calculator below does it for any Alberta property in 30 seconds — live, no signup. The output is the same number PJ would give you over the phone, just instant.

The Alberta sizing formula, explained

Every solar contractor in Alberta uses some version of this formula. Most don't show you the math. Here it is, in full:

kW = annual kWh ÷ (production factor × orientation × tilt × shading)

The production factor is the kWh a 1 kW array produces in a year on an ideal south-facing 30° roof in your region. PJ uses 1,200 kWh/kW/yr for Edmonton as a conservative defensible number across our 535+ install dataset since 2018. NREL's PVWatts model and NAIT's long-term Edmonton PV monitoring study both produce numbers in the 1,200–1,350 range; we deliberately quote the lower end so real-world systems exceed the projection rather than disappoint.

Worked example for a typical Edmonton home:

• Annual usage: 8,500 kWh/yr (a $165/month average bill at $0.23/kWh blended)
• Production factor (Edmonton): 1,200 kWh/kW/yr
• Roof: south-facing (1.00), medium pitch 15–30° (1.00), no shade (1.00)
• Required: 8,500 ÷ (1,200 × 1.00 × 1.00 × 1.00) = 7.08 kW
• Round up to nearest 0.5 kW: 7.5 kW
• Panel count: 7.5 kW ÷ 0.5 kW per panel = 15 LONGi Hi-MO 7 panels
• Roof area: 15 × 2.58 m² = ~38.7 m² (~417 sq ft) of usable south-facing roof, before setbacks
• Cash price at $2.85/W: $21,375 list, $19,238 cash after 10% cash discount

The calculator above does all of this live. If your roof is east-facing or partially shaded, the formula increases the recommended kW to compensate (because each watt produces less energy on a non-ideal roof, you need more watts to hit the same annual offset).

Six real-life Alberta sizing examples

Anonymised composites from our quote book, calibrated to typical Stellar customers. Each shows the inputs, the recommended size, and the reasoning. The patterns — not the individual numbers — are what matters.

Sizing by Alberta region

The production factor varies modestly by region. Use these as defaults if you don't know your exact PVWatts coordinates — the calculator above applies them automatically:

Why the variation matters: a 7 kW system in Edmonton produces ~8,400 kWh/yr; the same 7 kW in northern Alberta produces ~7,560 kWh/yr. If you're up north, you need a slightly bigger system for the same offset.

Future-proofing: sizing for EV, heat pump, addition

It is much cheaper to size for what's coming than to add panels later. A second install on the same roof typically carries a $1.50–$2.00/W premium over the marginal panel cost on the original install, because of new permit fees, mobilisation, electrical service work, and a second micro-generation interconnection application.

Typical Alberta load additions:

Caveat: don't size for hypotheticals. If you're thinking about an EV someday, don't add 2.5 kW. If you're buying an EV in the next 12–24 months, do. The Alberta Micro-Generation Regulation caps your system at your historical consumption + documented future load, so we'd rather right-size today than have your interconnection rejected for over-projection.

Alberta-specific gotchas to know before signing

The Micro-Generation 12-month cap (Alta Reg 27/2008)

Alberta's Micro-Generation Regulation requires residential systems to be sized to your historical 12-month consumption. Most utilities (EPCOR, Fortis Alberta, ATCO Electric, EQUS, REAs) allow up to ~110% of annual consumption with documentation — e.g., a delivery receipt for the EV you're about to buy, or a contractor estimate for the heat pump install scheduled next month. The hard ceiling for residential net metering is 150 kW. Systems above 150 kW exist (Stellar has installed up to 200 kW) but use AESO's large-tier framework rather than residential net metering. Full mechanics in our Alberta net metering guide.

Solar Club Alberta arbitrage changes the optimal size

If you sign up with a Solar Club Alberta retailer (Park Power, Bow Valley, Encor, ATCOenergy, Spot Power, plus 10 others), surplus solar exports at the HI rate of 35¢/kWh April–September, and you import at the LO rate of 8.40¢/kWh October–March. The math favours sizing to ~110% of consumption — the slight oversize generates summer export revenue at HI that more than pays for the extra panels in roughly 4 years. On a flat-rate retailer, the opposite is true: sized past 100% offset, you're producing kWh that export at a much lower rate (often the wholesale pool price ~5¢/kWh), so oversizing hurts payback. Full mechanics in our Solar Club Alberta guide.

The roof can be the binding constraint

Most single-family Alberta homes have 40–60 m² of usable south-facing roof, which fits 15–23 LONGi Hi-MO 7 panels (7.5–11.5 kW). Two-storey homes typically have more roof area than bungalows. If your math says you need 18 panels but your south face fits 12, the options are: (a) split across south + east-facing planes (microinverters make this work without dragging production down), (b) add a ground-mount where allowed (acreage only), or (c) accept partial offset and right-size to what fits.

North-facing rarely passes our sizing math

The orientation factor for true-north is ~0.55. To hit a 7 kW equivalent output you'd need to install ~12.7 kW of panels. The economics rarely work, even with current panel prices. We usually decline north-facing installs; the math will tell you the same thing if you set the orientation to NE/NW in the calculator above.

Five sizing mistakes we see all the time

1. Sizing to the bill amount, not the kWh. Bill amounts include delivery and admin charges that aren't offsettable by solar. Always size to actual kWh consumption, not dollars. The calculator above can convert from bill if needed but it's an approximation; pulling your real annual kWh from your utility's online portal is always more accurate.

2. Picking a panel count that "looks right" instead of running the math. "All my neighbours have 20 panels so I want 20 panels" is a marketing tactic, not a sizing methodology. Your usage and roof are different from your neighbour's. Size to your math.

3. Oversizing on a flat-rate retailer. If you're not on Solar Club, sizing past 100% of consumption just produces kWh that export at the wholesale pool price — often 5¢/kWh, compared to the retail rate of ~23¢/kWh you avoid by self-consuming. The marginal kW past 100% offset pays back in 25+ years.

4. Undersizing because of "a small bill today". If your bill is currently small but you're adding an EV, heat pump, or addition in the next 5 years, undersize today means a second install later at $1.50–$2.00/W premium. The future-proofing checkboxes on the calculator handle this correctly.

5. Not accounting for orientation properly. A 7 kW system on a true-south roof produces ~8,400 kWh; a 7 kW system on a west-facing roof produces ~7,140 kWh (15% less). If your usage is 8,400 kWh and your roof is west-facing, you need 8.5 kW, not 7 kW, to hit the same offset.

What if I don't have my annual kWh?

The fastest path is your utility's online portal. EPCOR, Fortis Alberta, ATCO Electric, and most Alberta retailers (Direct Energy, ENMAX Encompass, ATCOenergy, Spot Power, Park Power, etc.) show a 12-month usage chart by default on the dashboard. Look for a bar graph labelled "kWh" or "energy usage" — the total across 12 bars is your annual.

If the portal is unavailable: sum the kWh values from your last 12 monthly bills (every Alberta retail bill shows the kWh consumed in the billing period). If you don't have those, the calculator estimates from your monthly bill in dollars using a $0.23/kWh Alberta blended rate. The estimate is within ~10% for typical Alberta homes; PJ confirms exact usage on the assessment using your utility's data export.

If you've moved into your home within the last 12 months, your utility will sometimes show the previous occupant's usage on request — useful as a starting estimate. Otherwise the calculator's household-profile estimator (1–2 person small home through large acreage) gets you in the ballpark.

Roof area and panel layout (LONGi Hi-MO 7 specifics)

LONGi Hi-MO 7 500W panels measure 1.13 m × 2.28 m (3.71' × 7.48'). Each panel covers ~2.58 m² (~27.8 sq ft) of roof. Stellar installs them in landscape orientation on most residential roofs (height becomes 1.13 m, length 2.28 m per row).

Practical roof area calculation:

• Panel footprint: kW × 2 panels × 2.58 m² = total panel area
• Add ~15% for setbacks: 60 cm from roof edges (Alberta CEC fire setback), gaps around vents, chimneys, and skylights
• Total roof area needed: panel area × 1.15

Worked examples:

Most Alberta single-family bungalows have 40–55 m² of usable south-facing roof. Two-storey homes typically have 55–80 m². If your math calls for more area than you have, microinverters allow splitting across multiple orientations (south + east, for example) without the production penalty a string inverter would impose.

Sources & methodology

• Alberta production factor (1,200 kWh/kW/yr) — NREL PVWatts Calculator, Edmonton/central Alberta latitude with south-facing 30° pitch; cross-validated against NAIT's long-term Edmonton residential PV monitoring study. Deliberately conservative against the 1,300–1,400 kWh/kW typical on optimal roofs.
• Regional adjustments — PVWatts annual irradiance data for Calgary (+4%), Lethbridge/Medicine Hat (+8%), Red Deer (−2%), Athabasca (−10%).
• Orientation and tilt factors — NREL System Advisor Model (SAM) annual production multipliers vs reference south-facing 30° tilt.
• Shading factors — APsystems EMA real-world production data across Stellar's 535+ install dataset; deliberately conservative on moderate/heavy shading.
• Alberta Micro-Generation Regulation — Alta Reg 27/2008 under the Electric Utilities Act, as administered by the Alberta Utilities Consumer Advocate. 150 kW residential net metering ceiling.
• Solar Club Alberta rates — UTILITYnet Solar Club program documentation: HI 35.00¢/kWh, LO 8.40¢/kWh, Pre-Solar 7.25¢/kWh, current as of 2026.
• LONGi Hi-MO 7 panel dimensions — LONGi Solar product datasheet, 1.134 m × 2.278 m × 30 mm. 500 W STC. 30-year product + 30-year linear performance warranty.
• Stellar pricing — Stellar Upgrades' own 2026 quote book across 535+ residential installs since 2018.
• Future-proofing load estimates — Natural Resources Canada EnerGuide data for residential EVs and cold-climate heat pumps; Statistics Canada household consumption patterns by dwelling type.

If you find a number in this post that disagrees with a primary source, email info@stellarupgrades.ca — we update the post and calculator as the data moves.