How to Price a Solar PV Installation: Panels, Inverter, MCS and Grid Connection Costs

Quick Answer: A typical UK solar PV installation prices at £5,500-£8,500 for a 4kWp domestic system, £7,500-£11,500 for a 6kWp system, and £9,500-£14,500 for an 8kWp system, all installed and MCS-certified. Pricing breaks down roughly: panels 25-35%, inverter 12-18%, mounting and DC cabling 8-12%, scaffolding 8-15%, labour 15-25%, certification and DNO 3-6%. All grid-tied installations require Distribution Network Operator (DNO) connection — G98 notification for systems up to 3.68kW per phase, G99 application for systems above that threshold. MCS certification is required if the customer wants to claim the Smart Export Guarantee (SEG) on exported electricity, and all AC work must be notified under Building Regulations Part P 2013.

Summary

Solar PV is one of the fastest-growing trades in the UK with installation volumes more than doubling between 2022 and 2025. The work sits at the intersection of roofing, electrical and renewables — and the regulatory framework reflects that complexity. To install a grid-connected system the contractor needs MCS umbrella certification (which itself requires NICEIC, NAPIT or ELECSA electrical competence registration), DNO approval per installation, and compliance with both Building Regulations Part P (Electrical safety) and BS 7671:2018+A2:2022 wiring regulations.

The biggest pricing mistakes are: underestimating scaffolding cost (£600-£1,400 typical, more on awkward access), missing the DNO application fee or pre-install consent on G99 systems, underestimating the time required for hybrid or battery-coupled inverter commissioning, and forgetting that MCS commissioning paperwork is 4-8 hours of office time per install. Cowboys quote £4,500 fixed for a "4kW system" by skipping MCS, scaffolding, or DNO compliance — leaving the customer unable to claim SEG and the property uninsurable.

This guide covers: standard string inverter on-roof system, hybrid inverter with battery storage, microinverter systems, ground-mount installations, and the regulatory pathway. For specific battery storage detail see related articles; for roofing work see scaffolding pricing guide.

Key Facts

Quick Reference Table

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System Size Panel Count (430W) Inverter Scaffold Labour Total Cost
3.6kWp on-roof (no battery) 8 4kW string Yes 1.5 days £4,500-£6,800
4kWp on-roof (no battery) 10 5kW string Yes 1.5-2 days £5,500-£8,500
6kWp on-roof (no battery) 14 6kW string Yes 2-2.5 days £7,500-£11,500
8kWp on-roof (no battery) 18 8kW string Yes 2.5-3 days £9,500-£14,500
4kWp + 5kWh battery hybrid 10 5kW hybrid Yes 2-2.5 days £8,500-£12,500
6kWp + 10kWh battery hybrid 14 6kW hybrid Yes 2.5-3 days £12,500-£18,500
8kWp + 15kWh battery hybrid 18 8kW hybrid Yes 3-4 days £16,500-£24,500
4kWp microinverter system 10 10× IQ8 Yes 2-2.5 days £8,500-£12,500

Detailed Guidance

Inverter Choice: String vs Hybrid vs Microinverter

The inverter is the brain of the system and the choice drives both cost and future flexibility.

String inverter is the standard choice for new installs. All panels wired in series into one inverter; cheapest per kWp; simplest install. Drawbacks: any shading on one panel drops the whole string's output. Choose for unshaded south-facing arrays. Examples: Solis S6, Growatt MIN, Goodwe MS.

Hybrid inverter combines a string inverter with a battery interface. Critical for any system where battery storage is in scope now or anticipated within 5 years — retrofitting a battery later means replacing the inverter, so spec for the future. Cost premium £400-£900 over comparable string inverter. Examples: Solis Hybrid, Sungrow SH, Solax X3.

Microinverters (Enphase IQ8 series) put a small inverter on each panel. Eliminates string shading penalty entirely; module-level monitoring; longer warranty (25 years typical). Cost £150-£250 per panel — so 25-40% more system cost than string equivalent. Choose for shaded sites, split-roof arrays (E + W), or customers wanting top-tier monitoring.

Panel Selection: Tier 1, Wattage, Form Factor

The panel market changed rapidly 2022-2025. Today's standard:

The "right" panel is the one where the customer's payback works and the supply is reliable. Don't get drawn into a tier-1-only debate at the expense of the install date.

Mounting: On-Roof, In-Roof, Ground Mount

On-roof rail system — aluminium rails clamped to slate/tile via roof hooks; standard install, £18-£35 per panel in materials. Works on slate, plain tile, interlocking tile, and most composite roofing. Allow 6-12mm overhang of panel beyond rail end.

In-roof / integrated mounting — panels sit flush with the tile course, replacing tiles in the panel zone with a waterproof tray (e.g. GSE In-Roof System, Viridian Clearline). £45-£85 per panel premium, but very neat aesthetically and required by some Conservation Officers on listed buildings. Adds 2-4 hours of roofing work per array.

Ground mount — concrete or driven post foundation, A-frame rails. £80-£180 per panel of mounting cost. Only used where roof orientation is hopeless (e.g. north-facing) or for large rural systems. Planning permission may be required if the array is over 9m² or visible from a highway.

DNO Notification: G98 vs G99

The Distribution Network Operator (DNO) — the company that owns the local grid (UK Power Networks, Northern Powergrid, Scottish Power Energy Networks, etc.) — must be notified of any grid-connected solar PV. Two pathways:

Engineering Recommendation G98 (formerly G83) — for systems up to 3.68kW per phase (single-phase 3.68kW maximum, three-phase 11.04kW maximum). The installer notifies the DNO within 28 days of install via the online portal. No fee, no pre-install consent. Free at point of use.

Engineering Recommendation G99 (formerly G59) — for systems above 3.68kW per phase. Pre-install application required. The DNO assesses local network capacity and may approve, approve with constraints (e.g. export limiting), or refuse without network upgrade. Process takes 4-12 weeks. Fee £150-£550 depending on DNO. If the DNO requires network upgrade work (very rare for domestic), the cost could be £4,000-£15,000 — the customer bears this.

The 3.68kW per phase limit corresponds to inverter AC output, not panel DC rating. A 5kW inverter installed in single-phase property requires G99. Workaround: many installers fit a 4kWp panel array with a 3.68kW inverter to stay G98 (the inverter clips at peak — 2-4% annual yield loss, but no G99 hassle). Three-phase properties have much higher G98 threshold (up to 11.04kW) so G98 is usually achievable.

MCS Certification — Why It Matters

The Microgeneration Certification Scheme (MCS) is a UK certification scheme for renewable energy installers and equipment. To claim the Smart Export Guarantee (SEG) — the post-Feed-in-Tariff scheme where energy suppliers pay for exported electricity — the installation must be MCS certified. Without MCS, the customer cannot claim SEG, and the property generally cannot be sold with PV as a marketable feature.

MCS certification requires:

Approximately 4-8 hours of office time per install in commissioning paperwork. Cost £15-£35 per install in MCS fees, plus annual scheme membership.

Building Regulations Part P — Electrical Safety

All AC-side work on a solar PV system is notifiable under Building Regulations Part P 2013. The standard route is NICEIC / NAPIT competent person scheme self-certification — the installer notifies the scheme within 30 days, the scheme issues a Building Regulations Compliance Certificate to the customer.

Without Part P notification the customer cannot:

DC-side work (panels to inverter input) is not notifiable under Part P but is still subject to BS 7671:2018+A2:2022 (the Wiring Regulations). Specifically, Section 712 of BS 7671 covers solar PV installations — DC isolators, string current limits, fault current ratings.

Scaffolding — Always Quote Separately

Scaffolding is almost always required for a domestic solar install — the work involves moving 18-22kg panels onto a sloped roof, drilling roof hooks into rafters, and standing safely while making penetrations.

Cost considerations (see scaffolding pricing guide for detail):

Scaffolders charge by elevation and duration. If the panel install runs over schedule the scaffold has to stay up — re-erect fees are punishing if the scaffold has been struck. Always book scaffold for at least 1 extra day beyond the planned install date.

Battery Storage Add-On

Adding battery storage at the time of solar PV install is significantly cheaper than retrofitting later — the hybrid inverter is already in place, the DC cabling is sized for it, and the consumer unit work is done once.

Common battery sizes 2025-26:

Battery technology in 2025-26 is dominated by LFP (lithium iron phosphate) chemistry — safer than older NMC, lifetime 6,000-10,000 cycles at 80% depth of discharge, no thermal runaway risk. NMC chemistry still used in some EV-coupled systems but not recommended for residential static storage.

Battery storage in domestic dwellings is regulated under PAS 63100:2024 (Protection against fire of battery energy storage systems for use in dwellings) — sets clearance, ventilation, and detection requirements.

Common Pricing Mistakes

Frequently Asked Questions

Do I need planning permission for solar panels?

For most domestic installations, no — solar PV on a domestic dwelling is permitted development under The Town and Country Planning (General Permitted Development) (England) Order 2015 (Schedule 2, Part 14). Restrictions apply for: listed buildings (Listed Building Consent required); properties in conservation areas (may require planning); flat roof installations exceeding 0.2m above the roof; and ground-mounted arrays exceeding 9m² or 4m height. Always check with the local planning authority for borderline cases.

Can the customer get the work funded?

The ECO4 scheme (Energy Company Obligation, 2022-2026) covers some low-income households for solar PV installation. The Home Upgrade Grant 2 (HUG2) covers off-gas-grid properties in some local authorities. Smart Export Guarantee (SEG) is the main "earnings" route — energy suppliers must pay for exported electricity at a rate they set (typically 5-15p/kWh in 2025-26). VAT is 0% on supply and install of solar PV in dwellings until March 2027.

Why does the customer need MCS certification?

To claim Smart Export Guarantee payments from their energy supplier. To make the property marketable with the PV as a value-adding feature. To trigger MCS-backed insurance warranties on equipment. Customers without MCS certification lose the SEG income stream and may struggle to insure or sell the property as PV-equipped.

How long does a solar PV installation take?

A 4kWp on-roof system with no battery is 1.5-2 days of installation. A 6-8kWp system with battery storage and hybrid inverter is 2.5-4 days. Add 4-12 weeks for DNO G99 approval on systems above 3.68kW per phase (this is calendar time, not work time — the install can happen any time after approval).

What happens if the customer's roof is north-facing?

Yields on a true north-facing roof are typically 35-50% of equivalent south-facing in the UK. E/W split installations are increasingly common and only 10-15% less productive than south-only over the year, while better distributing generation across the day (which suits self-consumption). True north-only installs are rarely commercially viable; consider ground mount or decline the job politely.

How long do solar panels last?

Manufacturer warranties cover 25-30 years on power output (typically guaranteeing 80-87% of initial output after 25 years for premium panels). Physical lifetime is 30-40+ years. Inverters have shorter lifespans — 10-15 years typical, with replacement budgeted in customer payback calculations.

Regulations & Standards