TL;DR. The Alberta sizing formula: kW = annual kWh ÷ (1,200 × orientation × tilt × shading) — 1,200 being Edmonton's production factor per PVWatts. A typical 8,500 kWh/year home with a south-facing roof needs ~7.5 kW (15 panels, ~$21,000 cash). On Solar Club, size to ~110% of consumption to monetize summer exports; the regulation caps you near your own 12-month usage either way. The live calculator below does the math for your actual bill.
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.
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 550+ 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.
Profile 1 · Edmonton bungalow, retired couple
5,400 kWh/yr, south-facing. No plans
5.0 kW10 panels · 26 m²
Smaller system because consumption is low. We size to 100% offset on a flat-rate retailer. List $16,750, cash $15,075. Payback ~12 years. Why we don't oversize: Solar Club arbitrage wouldn't help meaningfully at this volume, and oversizing past consumption hits the Micro-Gen cap.
Profile 2 · Sherwood Park family of 4
9,200 kWh/yr, SE-facing roof, on Solar Club
8.5 kW17 panels · 44 m²
Sized to ~110% of consumption because they're on a Solar Club retailer (Park Power). Summer surplus exports at 35¢/kWh HI rate, winter imports at 5.90¢/kWh LO. Cash $24,225 (less the cash discount). Payback ~8 years. Why the slight oversize: the HI-rate export math pays for the extra panels in year 4.
Profile 3 · St. Albert family planning EV + heat pump
8,000 kWh/yr today, +EV +heat pump in 3 yrs
12.5 kW25 panels · 65 m²
Future usage = 8,000 + 3,000 (EV) + 5,000 (heat pump) = 16,000 kWh/yr. Sized for the future load now because adding a second install in year 3 carries new mobilisation, permit, and electrical setup costs (~$1.50/W premium vs the marginal kW today). Cash ~$34,400. Roof: 2 planes (front 15 panels, side 10 panels) at 96% SE orientation factor. The 5-year math justifies it.
Profile 4 · Leduc acreage, shop + well + heat
22,000 kWh/yr, roof + ground-mount option
18.5 kW37 panels · ~95 m²
15 panels on the main house roof + 22-panel ground-mount adjacent to the shop. Sized to ~100% offset because Solar Club isn't always optimal for acreages with REA-served properties. Cash ~$48,100. Payback ~11 years on flat rate, ~7.5 years if eligible for Solar Club. Why ground-mount: the south-facing main roof alone couldn't fit 37 panels; the ground-mount also benefits from optimal 35° tilt.
Profile 5 · Edmonton townhouse, condo board approved
4,200 kWh/yr, west-facing roof only
5.5 kW11 panels · ~28 m²
West-facing means 0.85× orientation factor, we add ~17% more kW to compensate for the production hit and still cover 100% of usage. Cash ~$15,700. Microinverters (APsystems DS3) handle the orientation penalty per-panel. Why we still recommend it: the math works because retail electricity rates in Alberta keep rising; an undersized west-facing system still pays back in ~10 years.
Profile 6 · Bonnyville farm, grain dryer + irrigation
85,000 kWh/yr, commercial-scale
75 kW150 panels · ground-mount
Commercial sizing, ground-mount on agricultural land adjacent to the main building. Cash ~$176,000 (at commercial pricing $2.30/W). Payback ~6 years because commercial loads run during solar production hours. Stays under the 150 kW Micro-Generation Regulation residential cap. For projects above 150 kW, we route through AESO's large-tier interconnection rather than residential net metering.
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:
| Region | Production factor (kWh/kW/yr) | Adjustment vs Edmonton |
|---|
| Calgary & metro | ~1,250 | +4% (slightly higher elevation, more clear days) |
| Southern AB (Lethbridge, Medicine Hat) | ~1,300 | +8% (lowest cloud cover in the province) |
| Edmonton & metro | ~1,200 | baseline (Stellar's home market) |
| Central AB (Red Deer, Olds, Lacombe) | ~1,180 | −2% |
| Northern AB (Athabasca, Slave Lake, Cold Lake) | ~1,080 | −10% (shorter winter days, more cloud) |
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:
| Adding... | kWh/yr added | Extra kW to size |
|---|
| Electric vehicle (15,000 km/yr at 20 kWh/100km) | +3,000 | +2.5 kW |
| Plug-in hybrid (10,000 km/yr electric) | +1,800 | +1.5 kW |
| Cold-climate heat pump (replaces gas furnace) | +5,000 | +4.0 kW |
| Heat pump (replaces electric baseboard) | −2,000 (efficiency gain) | −1.5 kW |
| 1,500 sq ft home addition | +2,000 | +1.5 kW |
| Pool / hot tub (heat pump pool heater) | +2,000 (summer) | +1.5 kW |
| Detached shop with 200A service | +3,000–5,000 | +2.5–4 kW |
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 5.90¢/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:
| System size | Panel count | Panel footprint | Roof area needed (with setbacks) |
|---|
| 5 kW | 10 panels | 25.8 m² (~278 sq ft) | ~30 m² (~322 sq ft) |
| 7 kW | 14 panels | 36.1 m² (~389 sq ft) | ~42 m² (~452 sq ft) |
| 10 kW | 20 panels | 51.6 m² (~555 sq ft) | ~59 m² (~635 sq ft) |
| 15 kW | 30 panels | 77.4 m² (~833 sq ft) | ~89 m² (~958 sq ft) |
| 20 kW | 40 panels | 103.2 m² (~1,111 sq ft) | ~119 m² (~1,278 sq ft) |
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 550+ 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 5.90¢/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 550+ 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.
Frequently Asked Questions
What size solar system do I need for an average Alberta home?
A typical Alberta home uses 7,500–9,500 kWh per year. At Edmonton's 1,200 kWh/kW production factor and a south-facing 30° roof, that works out to roughly 6.5–8 kW (13–16 LONGi Hi-MO 7 500 W panels). The calculator above sizes your specific home in seconds using your bill or annual kWh.
How do I find my annual kWh consumption?
Easiest: open your EPCOR, Fortis Alberta, ATCO Electric, or retailer's online portal and look for the annual usage chart. It's almost always shown as a 12-month bar graph. If you don't have online access, sum the kWh values from your last 12 monthly bills, every Alberta retail bill shows kWh used. If you don't have those either, the calculator estimates from your monthly bill in dollars (using a $0.23/kWh Alberta blended rate).
How many solar panels do I need?
Stellar standardises on LONGi Hi-MO 7 500 W panels. Multiply your system size in kW by 2 to get the panel count: 5 kW = 10 panels, 7 kW = 14 panels, 10 kW = 20 panels, 15 kW = 30 panels. Roof area required is about 2.58 m² per panel, so a 7 kW system needs ~36 m² (about 388 sq ft) of usable roof.
Should I oversize my system?
If you're on Solar Club Alberta (HI 35¢/LO 5.90¢ retailers, Park Power, Bow Valley, Encor, ATCOenergy, Spot Power, etc.), oversizing to ~110% of annual consumption is mathematically optimal because summer surplus exports at the HI rate. If you're on a flat-rate retailer, oversize at most to 100%, anything past that produces kWh you can't profitably export. The Alberta Micro-Generation Regulation also caps your system at your historical 12-month consumption (most utilities permit ~110% with documentation).
How does the Alberta Micro-Generation cap work?
Under Alta Reg 27/2008, residential systems must be sized to your historical 12-month consumption. Practically: your utility (EPCOR, Fortis Alberta, ATCO Electric, EQUS, or your REA) reviews the proposed system on the interconnection application and will reject or downsize a clearly oversized request. Most utilities allow up to ~110% of your annual consumption with documentation (e.g., a future EV or heat pump). The hard ceiling for net metering is 150 kW, larger systems exist in Alberta but use the AESO's large-tier framework. Not residential net metering.
Does roof orientation really matter that much?
Yes. A south-facing roof produces the most kWh per installed kW in Alberta; SE/SW is about 96% as good; E/W is about 85%; NE/NW about 72%; north-facing about 55% and we usually decline. The calculator above adjusts the recommendation automatically. Microinverters (Stellar uses APsystems DS3) recover some of the loss on partially shaded or split-orientation roofs by optimising panel-by-panel, that's another reason we standardise on them. See our
microinverter vs string inverter post.
I'm planning to get an EV next year, should I size for that now?
Yes. Adding an EV adds about 3,000 kWh per year (15,000 km annually at ~20 kWh/100km). It's much cheaper to size +1.5–2.5 kW into your initial install than to add panels later, the second install carries new permit, mobilisation, and electrical costs, often $1.50–$2.00/W premium over the marginal panel cost on the original install. Same logic applies to cold-climate heat pumps (+5,000 kWh/yr → +4 kW) and additions (+2,000 kWh/yr → +1.5–2 kW). The calculator above has checkboxes for each.
What size system fits on a typical Alberta home roof?
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. Acreages and farms with detached shops or ground-mount space can fit 15–200 kW. The calculator estimates roof area required so you can sanity-check against what you have.
