East & West Facing Solar Panels in Ireland 2026 — Yields, Maths & Self-Consumption

The conventional wisdom for solar panels in Ireland has been “south-facing or don’t bother.” That rule was reasonable in 2018. It’s wrong in 2026. The combination of three changes — TOPCon and HJT panels that capture more diffuse light, a Clean Export Guarantee (CEG) tariff that monetises midday surplus poorly compared with self-consumption, and battery prices that have dropped 60% since 2020 — has fundamentally rewired the orientation maths for an Irish rooftop.

In short: east and west facing roofs are now a perfectly sensible place to put solar panels in Ireland, and in some household profiles they out-earn a south-facing array. The 2024-era number you may have read — “east/west loses 18–20% versus south” — is no longer the relevant figure. The 2026 number is 10–14% with TOPCon panels, and once you factor in self-consumption shape, batteries and the CEG tariff, the net financial gap closes to 0–6% for most households.

This guide walks through the orientation maths with 2026 panel data, the CEG export tariff reality, how batteries flip the equation, planning, the SEAI grant treatment of orientation, and worked annual yield numbers for east, south and west aspects in Dublin, Cork and Galway.

The 2026 east/west yield reality

Annual generation depends on three factors that interact: total daylight hours on the panel, the panel’s response to the angle of incidence, and how much diffuse light (cloudy-day light) the panel can convert. Ireland is a high-diffuse-light environment — on a cloudy day, light isn’t coming straight from the sun’s position; it’s coming from the whole sky.

Old PERC panels (the dominant cell technology until about 2023) had a relatively narrow angle-of-acceptance window. East- and west-facing arrays therefore lost noticeably more than the geometric sun-angle would predict, because PERC was bad at squeezing energy out of diffuse light hitting at sharp angles. Result: 18–22% yield gap vs south facing.

TOPCon panels — the 2026 mainstream — have a wider angle of acceptance and better diffuse-light performance. HJT (heterojunction) and back-contact panels are even better. Result: 10–14% yield gap vs south facing for east or west aspects. Below is the rough 2026 yield matrix for a 4 kWp array at 35-degree tilt across three Irish cities:

Orientation	Dublin (TOPCon)	Cork (TOPCon)	Galway (TOPCon)
South (0°)	3,820 kWh/yr	3,950 kWh/yr	3,760 kWh/yr
South-east / South-west (45°)	3,680 kWh/yr	3,800 kWh/yr	3,620 kWh/yr
East / West (90°)	3,360 kWh/yr	3,470 kWh/yr	3,310 kWh/yr
East+West split (50/50)	3,400 kWh/yr	3,510 kWh/yr	3,340 kWh/yr
North-east / North-west	2,800 kWh/yr	2,890 kWh/yr	2,750 kWh/yr
North (180°)	2,400 kWh/yr	2,480 kWh/yr	2,360 kWh/yr

The gap between south and east/west is 12% in Dublin, 12% in Cork and 12% in Galway. Note that a 50/50 east/west split actually beats a pure east or pure west array, because you spread generation across more of the day and lose less to clipping at midday peaks. North-facing is a different conversation — the loss is 35–38%, which is rarely economic.

Why CEG export tariff changes the maths

The Clean Export Guarantee is the legal entitlement for Irish homeowners to be paid for solar electricity exported to the grid. Suppliers pay between €0.18 and €0.21 per kWh in 2026, depending on the supplier and the tariff. But you pay between €0.30 and €0.38 per kWh to import the same electricity from the same supplier — so every kWh you can use rather than export is worth 1.5–2x more.

This changes the orientation conversation entirely. A south-facing array generates a sharp midday peak. If you’re at work between 9 and 5, you don’t use most of that peak, so a lot of it gets exported at the lower CEG rate.

An east/west split array generates two smaller peaks — one in the morning and one in the late afternoon. Those line up with when people are actually home: morning coffee, kettle, shower, immersion top-up; evening dinner, dishwasher, washing machine, EV charging, TV. The self-consumption rate — the share of generated electricity you actually use yourself — jumps from typically 35–45% on a south array to 55–65% on a well-spec’d east/west array for the same household.

The financial implications:

Setup (4 kWp, Dublin household)	Annual generation	Self-consumption %	Annual financial return
South array, no battery	3,820 kWh	40%	€870/year
East/West split, no battery	3,400 kWh	60%	€830/year
South array, 5 kWh battery	3,820 kWh	72%	€1,140/year
East/West split, 5 kWh battery	3,400 kWh	82%	€1,030/year

Without a battery, south wins by 5% on the financials. With a battery, south still wins by ~10%. But the 12% generation gap shrinks to a 5–10% financial gap because of the self-consumption asymmetry. If your roof is east/west only, you’re not leaving 18% on the table the way a 2024 analysis would have told you — you’re leaving 5–10%. That’s a vastly easier installer-quote conversation.

When east/west actually beats south

There are three scenarios where the east/west split is genuinely better — not just “acceptable” but financially superior to south:

1. EV households that charge at home. EVs charge mostly at night, but most households also do a top-up around 6–7 pm when they come home. A west-facing array catches that 5–7 pm sun better than a south array (which has already dropped output by then). Saves CEG-rate-vs-import-rate arbitrage of about €0.18/kWh on every EV kWh.
2. Households with strong morning consumption shape. Big breakfast routine, school kids, kettle, immersion top-up, dishwasher cycle, two showers, hairdryer. An east-facing array generates real power between 7 and 10 am that’s used immediately. A south array doesn’t hit peak until midday.
3. Households with strong evening consumption shape. Late dinner cooking, electric oven, TV, charging laptops/phones, washing machine. A west-facing array catches the 4–7 pm window which is otherwise expensive grid electricity. Especially valuable if you’re on a time-of-use tariff where evening rates are higher.

The household pattern where south still wins clearly is the “everyone’s out from 8 to 6” profile with no EV and a heat pump that’s scheduled to run at midday. In that case the south peak lines up with the heat-pump load and you get genuine south-array advantage.

SEAI grant and orientation

The SEAI Solar PV Grant is €1,800 in 2026 for domestic systems. The grant amount is independent of roof orientation. South-facing, east-facing, west-facing, even a north-facing install (rare but technically allowed) all get the same €1,800. That’s because the grant supports installation cost, not generation. The only orientation-related grant condition is that the installer’s yield estimate has to be plausible — SEAI won’t pay for a system the installer expects to generate <1,500 kWh/year because it falls outside the grant scheme’s minimum yield assumption.

To qualify: home built and occupied before 1 January 2021, no prior Solar PV grant claimed at the MPRN, BER assessment performed within the qualifying window after install. Always check seai.ie for current scheme rules before signing a contract.

Planning permission and orientation

Irish planning rules treat solar PV as exempt development on a domestic roof up to 19 m² at front, side or rear (16 m² for an apartment), regardless of orientation. There’s a 0.5 m perimeter setback from the roof edge. That means an east, south or west-facing roof can take roughly the same array size without planning involvement.

Where planning gets specifically affected by orientation is in Architectural Conservation Areas (Drogheda, Limerick centre, Cork heritage core, Dublin Georgian conservation zones, etc.) where front-of-house visible installs — which east or south-facing arrays may be, depending on house orientation — get more scrutiny than rear-facing installs. The fix is usually all-black panels with hidden mounting; in stricter areas, a rear-only install is the only route.

Battery sizing for east/west households

If you’re going east/west, a battery makes more sense than it does for a south-facing setup, because:

• Your two generation peaks (morning + late afternoon) align reasonably well with consumption peaks, so battery cycles are shorter and the battery lasts longer.
• The midday trough — when both east and west panels are generating moderately rather than either peaking — lines up with the period when the battery would normally be discharging in a south setup. The east/west battery instead gets to top up steadily.
• Less wasted CEG-rate export per kWh of battery you add.

Practical sizing: 5 kWh for a 3–4 person household with normal evening peak; 10 kWh if you’re charging an EV at home and want to defer EV charging until the cheap-tariff night window. Above 10 kWh you start seeing diminishing returns unless you’re a heat pump household with a thermal store.

Inverter spec for east/west

One technical note that matters for east/west installs: the inverter needs to handle two separate strings (one east, one west) on different MPPT trackers. Almost all modern hybrid inverters have at least 2 MPPTs — the issue is whether your installer wires them as one combined string (wrong for east/west) or two separate strings (right).

If the installer wires them as one string, the east and west panels limit each other’s output during their respective peak periods, and you lose 8–12% of total generation. This is a quote-review check item: ask your installer explicitly “will east and west panels be on separate MPPT trackers?” before signing. The right answer is “yes, MPPT 1 east, MPPT 2 west.”

For inverter brands, the popular 2026 hybrid models — Solis S6 series, Sungrow SH series, Huawei SUN2000, GoodWe ET series, Fronius Symo GEN24 — all handle dual-MPPT east/west splits cleanly. Avoid string inverters that only have one MPPT for any east/west install.

What about a south + east or south + west combination?

Some Irish homes have an L-shaped roof or a south-facing main roof with an extension that faces east or west. The combination is genuinely excellent — you get the midday peak from south plus the morning or evening peak from the secondary aspect. Self-consumption rates on a south+east or south+west array hit 60–70% without a battery, and the total annual generation is essentially the same as a pure south install (the secondary aspect’s 12% gap is offset by the larger array area).

This is the highest-earning roof configuration in Ireland. If you have it, lean into it.

Worked example: Dublin east/west semi vs Cork south semi

Two homes, same household pattern (3 people, evening peak, no EV yet, 4,200 kWh annual consumption, gas heating):

Dublin east/west semi, 4 kWp split, 5 kWh battery

• Gross cost: €12,200 (battery + dual-MPPT inverter premium €400 vs single-MPPT)
• Net after €1,800 grant: €10,400
• Annual generation: 3,400 kWh
• Self-consumption: 82%
• Electricity bill saving: €780/year
• CEG export: €110/year
• Total saving: €890/year
• Payback: 11.7 years

Cork south semi, 4 kWp, 5 kWh battery

• Gross cost: €11,800
• Net after €1,800 grant: €10,000
• Annual generation: 3,950 kWh
• Self-consumption: 72%
• Electricity bill saving: €750/year
• CEG export: €200/year
• Total saving: €950/year
• Payback: 10.5 years

The financial gap is about 1.2 years of payback on a 25-year panel life. That’s not a reason to skip solar if you have an east/west roof.

East/West solar FAQ

Do east/west panels need different mounting? No — standard rail-and-clamp mounting works. The panels are mounted parallel to the roof slope as normal. The only spec change is the inverter (dual MPPT, not single MPPT).

Are east/west panels less efficient than south? They aren’t less efficient per panel — the same JA Solar, Longi or Trina TOPCon module produces the same power per W when light hits it. The reduction is in how much light hits the panel through the year. East and west receive 10–14% less total irradiance than south in Ireland.

Will my SEAI grant be smaller? No. The grant is €1,800 regardless of orientation.

Will the installer charge less because of the lower yield? Not usually. Install cost is dominated by labour, mounting hardware, panels and inverter — none of which change with orientation. The only line that may change is whether you want a dual-MPPT inverter (small €200–€400 premium over single-MPPT).

What about flat roofs — can I do east/west on a flat roof? Yes, with east-west tilt frames. On a flat roof, east-west panels at 10–15° tilt actually fit more total array area per square metre than south-tilt panels (because south-tilted panels need shading clearance behind them). For commercial flat roofs and apartment-block flat roofs, east-west is often the engineering default.

What yield drop should I expect on a north-facing roof? 35–40% vs south. North is the orientation that genuinely doesn’t pay back in Ireland in most cases. Even with CEG self-consumption logic, a north-facing array struggles to clear payback in 15–18 years on domestic scale.

Do I need to declare orientation when applying for the SEAI grant? No. The grant application doesn’t ask for orientation. Your installer’s system design (which they submit as part of the grant pack) describes the array layout.

How much extra does a battery add for an east/west setup? The same as for a south setup: €3,500–€4,800 for a 5 kWh battery installed alongside the PV system. East/west households tend to extract slightly more value per battery kWh because the battery cycles match the consumption shape better.

If my roof has a small south section and a larger east section, which should I cover? Cover as much of both as fits. A 6 kWp install split as 2 kWp south + 4 kWp east generates more total energy and earns more annually than a 4 kWp south-only install, even after accounting for the lower per-kWp yield on the east section.