Solar PV Installation at London Homes 2025: Planning, Costs, MCS, and the Smart Export Guarantee

Solar PV panels installed on residential buildings in England are generally permitted development under Part 14 (renewable energy installations), Class A of Schedule 2 of the Town and Country Planning (General Permitted Development) (England) Order 2015 (GPDO). The permitted development right applies subject to the following conditions: the panels must not protrude more than 0.2m beyond the surface of the roof slope (measured perpendicular to the roof slope); the installation must be designed and sited to minimise its effect on the external appearance of the building and the amenity of the area; when no longer needed, the panels must be removed as soon as reasonably practicable; on land within the curtilage of a listed building or a site designated as a Scheduled Monument: solar panels are NOT permitted development and listed building consent is required. For the purposes of the roof panel PD right: the 0.2m protrusion limit applies to the panel depth above the roof surface — most modern solar panels are 30-40mm deep and mount on a racking system at 50-100mm above the roof surface, typically well within the 0.2m (200mm) limit. Conservation areas: the PD right for solar PV on roof slopes visible from a highway is removed in conservation areas. This means: in a conservation area, solar panels on a roof slope that faces a highway require planning permission. Solar panels on a rear or side roof slope not visible from a highway remain PD in a conservation area. Many London terraces in conservation areas have south-facing front roof slopes (facing the street) — in these cases, the most productively positioned panels (tilted south on the front slope) would require planning permission. Rear or side roof slope panels in the same terrace (less productively positioned) remain PD. Listed buildings: any material alteration to the fabric of a listed building, including the installation of solar panels, requires listed building consent. In practice, listed building consent for solar PV on a listed building is very difficult to obtain for panels on the primary elevation — panels on a less visible secondary roof may be acceptable with appropriate design. Flat-mounted solar panels on a flat roof: the PD right applies to panels on a flat roof — panels on a flat roof are permitted development if they do not exceed 1m above the surface of the roof (excluding any chimney stacks) and the installation does not take up more than 50% of the roof area. Ground-mounted solar panels within the curtilage of a house: permitted development under Class A(a)(ii) — provided the installation area is no more than 9 sq m in two panels, the panel is no more than 4m above ground level, the installation is at least 5m from any highway boundary, and the panels are at least 5m from the boundary of the curtilage.

MCS (Microgeneration Certification Scheme) accreditation: for a domestic solar PV system to qualify for the Smart Export Guarantee (SEG) and for any future government grants or subsidies, the installer must be MCS-accredited and the system must be MCS-certified on completion. MCS is the quality assurance framework for small-scale renewable energy installations in the UK. All MCS-accredited installers undergo regular audits and must design and install systems to MCS technical standards. Ensuring your chosen installer is MCS-accredited is essential for: eligibility for SEG payments (the energy supplier requires an MCS certificate); having the system performance guaranteed to the MCS standard; re-sale of the property (an MCS-certified system is clearly documented for buyers' solicitors). You can check an installer's MCS accreditation status on the MCS website (mcscertified.com). Smart Export Guarantee (SEG) 2025: the Smart Export Guarantee (SEG) replaced the Feed-in Tariff (FiT) scheme (closed to new applicants in March 2019) as the mechanism for compensating domestic solar PV generators for electricity exported to the grid. Under SEG, all energy suppliers with 150,000 or more domestic customers are required to offer at least one SEG tariff to eligible small-scale generators. SEG tariff rates: SEG tariffs are set by the suppliers and vary — in 2025, competitive SEG tariffs range from 5p/kWh to 15p/kWh depending on the supplier and tariff product. Some suppliers offer 'smart' SEG tariffs that vary by time of day (paying more for export during peak demand periods). For a 4kWp system that exports approximately 40% of its generation (1,400-1,600 kWh/year exported), the SEG income at 7.5p/kWh is approximately £105-£120/year. SEG is not a fixed income scheme — tariff rates can change when a tariff product ends. System sizing guidance for London homes: London receives approximately 1,050-1,150 peak sun hours per year (compared to approximately 1,200-1,300 in the south-west of England). A typical London 4kWp system (approximately 10 x 400W panels on a standard south-facing pitched roof): annual generation — approximately 3,400-3,800 kWh/year; self-consumption of generation (without battery storage) — approximately 40-55% (depending on home occupancy patterns and load profile); grid export (40-55%) — approximately 1,500-2,000 kWh/year with SEG payment. To maximise self-consumption (and therefore value from the system), adding battery storage enables generation to be used in the evening when occupancy is higher. Battery storage: a domestic battery storage system (e.g. Givenergy, SolaX, Sonnen, Tesla Powerwall — 5-10kWh capacity) costs £3,000-£6,000 supply and install (2025), with VAT at 0% for residential battery storage systems directly associated with solar PV installations. Adding battery storage typically increases self-consumption from 45-55% to 70-85% of annual generation, improving the value of the solar PV system. Compatibility with heat pumps and EV chargers: solar PV is highly compatible with air source heat pumps (ASHPs) and EV home chargers — both increase on-site electricity consumption and allow more of the solar generation to be self-consumed. A home with solar PV, battery storage, an ASHP for heating, and an EV charger can achieve very high self-consumption rates (80%+), improving the overall economics of all three technologies together.

Solar PV system costs (London 2025, all-in supply and install, VAT at 0% for residential solar PV): 3kWp system (7-8 panels — suitable for a 1-2 person household or a smaller roof area): £5,000-£7,000. 4kWp system (9-11 panels — suitable for a typical London 3-bed family home): £6,000-£9,000. 5kWp system (12-14 panels — suitable for larger roof or higher electricity users): £7,500-£11,000. 6kWp system (15-17 panels — larger households or properties with high electricity consumption including heat pump or EV): £9,000-£13,000. Battery storage addition (5-7kWh — suitable for most London family homes): £3,000-£5,000. Battery storage addition (10kWh — larger households, higher self-consumption): £4,500-£6,500. VAT on solar PV: residential solar PV installation (panels, inverter, mounting, wiring, and associated battery storage) has been zero-rated for VAT since April 2022 (extended from the original 5% reduction). This VAT reduction is a significant saving and means the prices above are VAT-inclusive (no VAT to add). What the installation involves: a typical solar PV installation takes 1-3 days for a standard system on a pitched roof: Day 1: scaffold erection (required for most pitched roof work — scaffolding cost is typically included in the all-in price and takes 0.5-1 day to erect); Days 1-2: roof penetration/flashing, installation of the racking/mounting system, installation of panels to mounting rails; Day 2-3: DC cable installation from panels to inverter location, inverter installation (typically in the loft or garage), connection to the consumer unit, installation of generation meter; commissioning, testing, and handover — including connection to the inverter's monitoring system (almost all modern inverters have cloud monitoring apps showing real-time generation and lifetime performance). The installation requires a qualified electrician for the AC connection to the consumer unit — this is notifiable work under Part P. A Generation Meter (import/export meter) is required by the Distribution Network Operator (UK Power Networks in London) to register the generation for SEG — this is arranged by the installer as part of the MCS certification process. London roof considerations: many London Victorian terraces have: narrow roof pitches (2.4m wide per slope in some cases — limiting panel count on each slope); party wall obligations if scaffolding or work is needed on or over the neighbour's side of the roof; chimneys and dormer windows that create shading (the installer should carry out a shading analysis — using tools such as PVsyst or RoofStream — to model the impact of shading on annual generation). Always obtain quotes from at least two MCS-accredited installers and ask each to provide a site-specific shading analysis and predicted generation report (sometimes called a KWh prediction report) before committing to the installation.