Scotland's New Build Solar Regulations: What Section 6 Actually Requires

How Solar Dropped Out of Scottish Building Regulations

Scotland was ahead on this for years. The 2015 Section 6 energy standards tightened dwelling emission rates enough that PV was routinely specified on gas-heated new builds to meet compliance. England's 2021 Part L uplift had a similar effect later.

Then the New Build Heat Standard landed in April 2024 and banned gas and oil boilers in all new dwellings. Good move — but the old Section 6 had two calculation pathways: one for gas-heated homes (which commonly needed PV to pass) and one for heat pump homes (which didn't). When gas boilers were removed, every new build defaulted to the heat pump pathway. Solar was no longer needed to pass the calculation.

Nobody planned this. It fell through the cracks during the changeover.

What the Regulations Actually Require Right Now

From April 2024

• Zero direct emissions heating in all new dwellings — typically an air-source heat pump, though electric heating and heat networks are permitted
• No gas or oil boilers
• Solar panels are not required — the developer decides whether to include them

From 31 March 2028

• Passivhaus equivalent standard becomes mandatory (Section 6 Stage 2)
• Focus is on fabric performance: insulation, airtightness, MVHR ventilation
• Solar and battery storage still not confirmed — the Stage 2 consultation will decide this

Why the Maths Still Says Install Solar at Build Stage

Even without a legal mandate, the financial case for including solar at new build stage is strong — and the technical installation is significantly simpler than retrofitting.

System Sizing for a Typical Scottish New Build

A standard 3–4 bedroom new build with a heat pump typically draws 4,000–5,000 kWh/year in electricity. A 4kW solar array covers a meaningful portion of that:

• Panels: 10 × 400W monocrystalline (JA Solar DeepBlue 4.0 or equivalent) — standard dimension 1,722 × 1,134mm, roughly 20m² of usable roof
• Inverter: Single-phase hybrid inverter rated 3.6kW–5kW (Growatt MIN 5000TL-XH, Fox ESS H3, or SolarEdge with StorEdge interface). A hybrid inverter at build stage means you can add battery storage later without rewiring the AC side
• DNO notification: A system up to 3.68kW export (single-phase) falls under G98 — your installer notifies your DNO (SP Energy Networks across most of Central Scotland) with a simple online form. Above 3.68kW export requires G99 application, which takes 10–12 weeks. At build stage, this lead time is easily absorbed into the construction programme
• Consumer unit integration: New build means a new consumer unit from day one. The solar supply gets its own dedicated MCB (typically 20A Type B) on a dedicated circuit from the inverter. No retrofitting into an existing board, no capacity concerns

The Cost Advantage of Build-Stage Installation

Adding solar during construction avoids several retrofit costs entirely:

• No scaffolding hire (the roof isn't finished yet)
• Rail and bracket fixings go directly onto battens before tiles are laid — no drilling through weathered tiles or searching for rafters
• Cable routes from roof to inverter location are planned into the first-fix electrical design
• The electrician doing first-fix wiring runs the DC cable and AC isolator positions as part of the standard scope

For self-builders, this typically saves £800–£1,200 compared to a post-completion retrofit of the same system.

Annual Savings

A 4kW system on an energy-efficient new build in Scotland generates roughly 3,400–3,800 kWh/year (based on MCS PVGIS data for Central Scotland at 35° pitch, south-facing). With a heat pump increasing baseload electricity demand, self-consumption rates of 40–50% are realistic without a battery, rising to 70–85% with a 5–10kWh battery.

Estimated annual savings: £974–£1,151 — higher than a typical existing home (~£530/year) because new builds consume more electricity overall (heat pump, MVHR, induction hob).

What Self-Builders Need to Tell Their Architect

If you're building your own home in Scotland, solar won't appear in the standard Section 6 compliance calculation unless your architect specifies it. You need to explicitly request:

1. Roof orientation and pitch optimisation — south-facing at 30–40° is ideal; east/west splits work if the ridge runs north–south, but you'll need a dual-MPPT inverter or optimisers to handle two orientations
2. Structural loading — modern panels weigh around 20kg each. Ten panels add roughly 200kg to the roof structure. Your structural engineer needs this in the design, not as an afterthought
3. Cable containment — DC cable routes from roof to plant room/utility should be included in the architectural drawings at Stage 3 (developed design). Running DC cables through a finished, airtight Passivhaus envelope after completion is a nightmare
4. Inverter and battery location — hybrid inverters generate some heat and noise (fan cooling). Plan a garage, utility room, or plant room location with adequate ventilation, not a bedroom wall
5. Metering position — the generation meter and export meter (for SEG payments) sit next to the consumer unit. Make sure there's physical space on the board

The 0% VAT Window

Solar panel installation is zero-rated for VAT until 31 March 2027. After that, installations revert to 5% VAT (reduced rate) under current HMRC rules. On a £6,000–£8,000 system, that's a saving of £300–£400 by acting before the deadline.

For new builds completing in 2026 or early 2027, this is a straightforward win — the solar install happens during construction and invoicing falls within the VAT relief window.

What Happens Next

The Scottish Government's Stage 2 consultation on the Passivhaus equivalent standard is expected to open soon. This is when we'll find out whether solar panels and battery storage will be written into Scotland's new build future.

Solar Energy Scotland, backed by the wider industry, is pushing hard. The EU's recast Energy Performance of Buildings Directive introduces phased rooftop solar requirements with new residential buildings expected to be included by 2029/2030. England is mandating solar from 2027. The argument that Scotland — which pioneered PV on new builds a decade ago — should be left behind is a difficult one to make.

In the meantime, every new build we wire gets a hybrid inverter and the DC infrastructure for solar, whether panels go on now or later. It's an extra few hundred pounds at first-fix and it saves thousands if regulations change.

---

---

MCS-certified solar installers serving Stirling, Falkirk, Dunblane, Bridge of Allan, Bearsden, and Central Scotland.