Solar Panels on New Builds: What to Expect

Since June 2023, new homes in England must produce significantly less carbon than before, effectively mandating solar panels or equivalent low-carbon technology on most new builds. If you're buying a new build, here's what to expect, what to check, and what to negotiate.

The Regulatory Position

The Future Homes Standard (full implementation expected 2025) will require new homes to produce 75–80% less carbon than the 2013 standard. In the meantime, an interim update to Part L of the Building Regulations (June 2023) requires a 31% reduction compared to previous standards.

Most housebuilders meet these requirements by installing solar panels, because:

• Solar PV is the most cost-effective way to achieve the required carbon reduction
• Panels are easy to integrate during construction
• Alternative approaches (ultra-high insulation, heat pumps alone) are often more expensive

This means the vast majority of new homes being built today come with some solar panels included in the purchase price.

What Do Builders Typically Install?

The standard new build solar package is often the minimum to comply with regulations:

• 2–3kW system (5–8 panels) on most standard houses
• 3–4kW system (8–10 panels) on larger detached homes
• Standard string inverter — functional but basic
• No battery storage — batteries aren't required by regulations
• MCS certification — should be provided but always confirm

This is a decent starting point but often less than what would be optimal for the homeowner. A 2.5kW system generates around 2,000–2,500kWh per year — useful, but a 4kW+ system would generate significantly more and reduce electricity bills further.

What to Check Before You Buy

System Size vs Your Needs

A 2.5kW system is a starter system. If you're going to be running a heat pump, charging an EV, or have high electricity usage, it won't cover much. Ask whether a larger system (4kW+) is available as an upgrade or option.

Panel Quality

Not all panels are equal. Some builders use budget panels from lesser-known manufacturers to minimise costs. Check:

• Is the panel manufacturer well-established? (JA Solar, Trina, Canadian Solar, LONGi are all reputable)
• What wattage per panel? (Below 380W is now behind the curve)
• What's the panel warranty? (25-year product warranty is standard from quality manufacturers)

Inverter Quality

The inverter is the component most likely to need replacement during the system's life. Check the brand — Solis, GivEnergy, SolarEdge, Fox ESS, and Growatt are all reputable. A cheap unbranded inverter is a red flag.

Roof Orientation

New build layouts are designed around plot efficiency, not solar optimisation. Check which direction the solar panels face:

• South: Optimal — 100% generation potential
• East or west: Good — 80–85% of south-facing output
• North: Poor — question why panels were placed here (sometimes builders do this to meet regs on paper while facing panels away from neighbours)

Wiring for Future Expansion

Ask whether the electrical system is pre-wired for:

• Battery storage (even if not included now)
• EV charging
• Additional solar panels

Adding these later is much cheaper if the wiring is already in place.

GivEnergy All-in-One 5kW Hybrid Inverter

£1,200

rated power kw

5

max pv input kw

7.5

mppt channels

2

battery voltage v

48V

View on Amazon

Affiliate link — we may earn a small commission at no extra cost to you

Negotiating Upgrades

Most national housebuilders offer upgrade packages. Solar-related options may include:

• Additional panels — Expanding from 2.5kW to 4kW+ (typical cost: £1,500–3,000)
• Battery storage — Adding a 5–10kWh battery (typical cost: £3,000–5,000)
• Premium inverter — Upgrading to a hybrid inverter that supports battery addition later
• EV charger — Often available as a combined package with solar

These upgrades are almost always cheaper during construction than retrofitting later, because:

• Scaffolding is already up
• The roof is accessible
• Electrical connections can be designed in from the start
• The builder can bulk-buy equipment at trade prices

Negotiation Tips

• Housebuilders are used to negotiating — flooring upgrades, kitchen upgrades, and now solar upgrades
• Ask for the upgrade cost to be included in the house price (it then gets covered by your mortgage)
• If the market is slow, builders are more willing to include upgrades at reduced cost or free
• Get upgrade specifications in writing before exchange of contracts

JA Solar JAM54D41 450W N-type TOPCon

£82

watt peak

450

efficiency pct

22.8

dimensions mm

1722 x 1134 x 30

weight kg

21.5

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MCS Certification and Smart Export Guarantee

Your new build solar installation should come with MCS certification. This is essential for:

• Claiming Smart Export Guarantee payments for surplus electricity
• Validating the system's performance specifications
• Meeting building regulations compliance evidence

Ask for the MCS certificate before you complete on the purchase. If the builder hasn't arranged MCS certification, this is a significant omission — push back firmly.

After Moving In

Once you're in your new home:

1. Register for SEG: Contact an energy supplier offering the Smart Export Guarantee and register your system. This earns you payment for exported electricity.
2. Understand your system: Ask the builder or installer for a handover session explaining how to read the inverter display and monitor generation.
3. Set up monitoring: Most modern inverters have an app. Set this up to track daily generation and identify any issues early.
4. Consider adding a battery: If your system doesn't include one, a battery can be retrofitted. This is the single most impactful upgrade for maximising self-consumption.

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