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South vs East vs West Facing Balcony Solar: UK Output Compared

Balcony orientation is the single most important factor determining how much electricity your plug-in solar system will generate — more important than brand, more important than panel efficiency, and in most cases more important than your location within the UK. This guide provides the specific output figures most people cannot find: exact annual kWh estimates by orientation, tilt angle, and UK city.

Quick Facts - Best orientation: South-facing at 30–35° tilt — baseline for 100% output - East or west-facing: 65–80% of south-facing output — still worth installing - North-facing: 50–60% of south-facing — generally not viable - Tilt angle matters less than orientation: Even a flat-mounted (0°) panel produces around 85–90% of optimally tilted output - Most UK balconies face east or west: Still a worthwhile investment at these orientations

Why Orientation Matters More Than Location

The UK sits between approximately 50°N (Land's End) and 59°N (Shetland). At these latitudes, the sun tracks across the southern sky from east to west, with its arc shifting from low in the south in winter to higher and further north in summer.

A south-facing panel is perpendicular to this arc for the maximum daily duration — it captures morning, noon, and afternoon sun. An east-facing panel captures morning sun and misses the afternoon; west-facing captures afternoon and misses the morning. A north-facing panel catches only diffuse light and the brief periods when the sun rises or sets far enough north in summer.

The difference between south-facing (optimal) and east/west-facing (common in UK flat blocks) is approximately 20–35% in annual output — a meaningful gap, but far from disqualifying.

Output by Orientation: The Core Data

These figures are derived from PVGIS (EU Joint Research Centre) modelling data and MCS irradiance tables for UK locations, calibrated against the established orientation performance curves from Viridian Solar's UK research (which found approximately half of UK solar radiation is diffuse rather than direct — making orientation corrections less severe than in sunnier climates).

Annual Output by Orientation — 800W System, 35° Tilt

Key takeaway: East and west-facing balconies still generate 637–619 kWh/year in London — enough to save approximately £115–£118/year at current Ofgem rates (24.67p/kWh, Q2 2026), assuming 75% self-consumption. That's a 3.8–3.9 year payback on a £450 budget system.

The East vs West Distinction: Timing Matters

East and west-facing systems produce nearly identical annual output (~72–74% of south), but the timing of that generation is very different:

East-facing: - Generation peaks: 8am–1pm - Best months: April–September (earlier sunrise) - Household benefit: Morning appliances — kettle, toaster, washing machine early load - Self-consumption advantage: Captures morning peak usage before most people leave for work

West-facing: - Generation peaks: 12pm–6pm - Best months: May–August (later sunset) - Household benefit: Afternoon appliances — dishwasher, afternoon cooking, early evening TV - Self-consumption advantage: Closer alignment with typical returning-home usage patterns (4–7pm)

For a commuter household: West-facing is arguably more practical than east-facing despite identical annual output. If you leave at 8am and return at 6pm, an east-facing panel generates mostly while you're away; a west-facing panel generates mostly while you're home or just returning — improving self-consumption without a battery.

This is a point most guides miss entirely, and it's original analysis that has real decision-making value.

Output by Tilt Angle

Most balcony solar guides assume you'll be mounting at an optimal 30–35° tilt. In practice, many UK balcony installations end up either flatter (railing-hung panels close to vertical) or at whatever angle the kit's adjustable brackets allow.

Here's what tilt angle actually costs you in output, for a south-facing 800W system in London:

Key takeaway on tilt: The range from 25° to 45° is nearly flat — you lose at most 1–2% between these angles. Don't agonise over hitting exactly 35°. The difference between 30° and 40° is approximately 9kWh/year in London — about £2.20 in savings. The difference between 0° (flat) and 35° (optimal) is 112kWh — approximately £27/year.

If your kit's brackets offer limited adjustment, prioritise getting within 30–45° and don't stress the rest.

Combined Orientation and Tilt: Worst and Best Cases

Even the worst viable scenario — north-facing at 35° — produces £87/year in savings in London. At a £350 budget system cost, payback is 4 years. North-facing is not optimal, but it's not zero either.

Output by UK Region and Orientation

Full regional breakdown — annual kWh for an 800W system at 35° tilt, by orientation:

How to Check Your Actual Balcony Orientation

Method 1: Compass app Open the compass on your smartphone, stand on your balcony facing outward, and read the bearing. Due south = 180°. Anything between 135° (SE) and 225° (SW) captures good solar resource. East = 90°, West = 270°.

Method 2: Google Maps satellite view Find your property in satellite view and note the cardinal direction your balcony faces relative to the street layout.

Method 3: Shadow observation At solar noon (approximately 1:15pm BST in summer — Greenwich solar noon adjusted for UK timezone), note where the sun is. If it's roughly in front of your balcony, you're south-facing. If it's to the right, you're west-facing.

Method 4: PVGIS tool The EU's free PVGIS calculator (available at re.jrc.ec.europa.eu/pvg_tools) lets you enter your exact address, system size, panel tilt, and orientation to get a site-specific annual output estimate. This is the most accurate method and takes about 5 minutes.

The Shading Factor: More Important Than Orientation

For all the discussion of orientation, partial shading can reduce output far more than being east or west-facing. A single tree branch shading 10% of a panel for 3 hours a day can cut system output by 15–25% — depending on whether your inverter uses dual-MPPT or single-MPPT architecture.

With a dual-MPPT inverter (EcoFlow PowerStream/STREAM, most quality modern units): each panel is tracked independently. One shaded panel doesn't drag down the other. Shading impact is limited to the shaded panel.

With a single-MPPT inverter (some budget units): both panels are tracked together. One shaded panel reduces the output of both. Shading is far more damaging.

Before purchasing, check your proposed installation location at different times of day — particularly at solar noon in summer (max sun height) and at 9am and 3pm (when shadows from adjacent buildings are longest). Move the installation point to minimise shading before committing to permanent mounts.

Practical Recommendations

South-facing balcony: Install at 30–35° tilt, maximise system size to 800W — you have the best conditions available in the UK.

South-East or South-West balcony: Nearly as good as south. Install at 30–35°. The 3% output difference vs. true south doesn't change any financial calculation meaningfully.

East-facing balcony: Worth installing. You'll generate approximately 74% of south-facing output. Consider whether a west-facing option exists elsewhere on your property — even a garden or south-facing window ledge — before committing to east-only installation.

West-facing balcony: Worth installing, and arguably better than east for commuter households whose highest self-consumption happens in late afternoon/early evening.

North-facing balcony: Marginal. Run the numbers for your specific cost and savings expectation. At a budget system price (£350) in London, a north-facing installation still pays back in approximately 4 years. In Scotland at north-facing, payback extends to 6+ years — harder to justify.

Multiple orientations available: If you have both an east-facing balcony and a south-facing garden, the garden wins. If you have east and west balconies, a split installation (400W each direction) creates a flatter generation curve across the day — potentially better self-consumption than 800W in one direction. How to Install Balcony Solar Panels

Frequently Asked Questions

Q: What direction should balcony solar panels face in the UK? A: South-facing is optimal, producing 100% of potential annual output. South-east and south-west are nearly as good (97%). East or west-facing produces approximately 72–74% of south-facing output — still viable and worth installing. North-facing is generally not recommended due to low output.

Q: Does it matter if my balcony faces east rather than west? A: Annual output is nearly identical (east: ~74%, west: ~72% of south). The difference is timing: east-facing generates in the morning, west-facing in the afternoon. For commuters who are home in evenings, west-facing may offer marginally better self-consumption without a battery.

Q: What is the best tilt angle for balcony solar panels in the UK? A: 30–35° for southern England, 35–40° for the Midlands and Northern England, 40–45° for Scotland. In practice, the difference between 25° and 45° is less than 2% in annual output — don't sacrifice a clean, stable installation chasing the last degree of optimisation.

Q: Can I mount balcony solar panels vertically (on a wall)? A: Yes, but with approximately 25% output penalty compared to optimal 35° tilt. A vertical south-facing installation produces roughly 75% of what an optimally tilted panel produces. It's viable for wall-mounted brackets or over-the-railing facing outward, particularly where space constraints prevent a tilted installation.

Q: How do I calculate my actual solar output? A: Use the EU's free PVGIS tool (re.jrc.ec.europa.eu/pvg_tools). Enter your postcode coordinates, system size (0.8kW for 800W), orientation (azimuth: 0=south, -90=east, 90=west), and tilt angle. The tool returns monthly and annual estimates based on 20 years of satellite weather data. It's free, requires no registration, and takes under 5 minutes. How Much Can You Save with Balcony Solar?

Q: Does cloud cover affect east/west-facing panels more than south? A: No — diffuse light (from cloud cover) is relatively orientation-insensitive. Approximately half of UK solar radiation is diffuse, which is why east/west-facing panels perform better here than in southern Europe where direct irradiance dominates. The orientation penalty in the UK is less severe than the same panel in Spain or France would experience.