Letchworth Interactive Retrofit House

Solar photovoltaics (PV)

Summary

Solar photovoltaic (PV) panels capture energy from solar radiation and convert it into electricity. This electricity can be supplied directly to your home to power e.g. appliances, lighting, a heat pump or an EV charger. Solar panels can provide ‘free’ (after purchase and installation costs have been recovered), renewable and clean electricity which can significantly reduce energy bills. 

Any electricity not used can be sold back to the grid through your energy supplier, or with a solar diverter can power an immersion heater in a hot water tank to store hot water for later use. Alternatively, with a ‘hybrid’ system the electricity can be stored in a battery for later use (e.g. at peak times when electricity is more expensive). A hybrid system with a battery will have a higher upfront cost but can be become more cost-effective in the long run.

There are a number of different types and installation methods for solar panels including on-roof mounted (most common), in-roof (installed within a section of the roof, flush with roof tiles) and solar tiles (solar PV tiles installed in place of regular roof tiles).

Tips for optimum performance:

  • Ideally install solar panels on a south facing roof, although east and west facing roofs can also work well.
  • Avoid panels being shaded by existing objects on or near the roof, such as chimneys and overhanging trees.
  • Invest in tech to monitor the reliability of the system and allow immediate identification of any issues which can be rectified quicker.

Cost/difficulty

MEDIUM COST – Approximately £6,000–£11,000 (5kWp array of 10–12 panels) – The Surrey Home Energy Improvement Guide (2025), page 40.

MEDIUM DIFFICULTY – Professional installation required by a qualified installer (preferably Microgeneration Certification Scheme accredited).

Applicability in Letchworth

Applicable, subject to certain requirements being met. 

The PV (Photovoltaic) Panels Guidance state that:

Letchworth Garden City Heritage Foundation is supportive of Letchworth residents’ wishes to install renewable technologies in order to power their homes. To ensure the continued maintenance of the Garden City’s character, the following guidance has been issued.

Your application is more likely to be approved if you follow the following guidelines. If your proposal does not fit within the criteria stated below, please contact the Heritage Advice Service on: 01462 530335 or home@letchworth.com.

Heritage Character Area (HCA)

Acceptable installation in the HCA

  • Panels should be positioned on rear roof pitches, on rear outbuildings, or as a ground array in back gardens.
  • The design of the array must be balanced and symmetrical; rectangular and straight-lined installations will be required.

Unacceptable installation in the HCA

  • Panels should not be located on any street facing roof pitches.
  • Panels should not overhang the roof slope.

Panels may not be appropriate for Homes of Special Interest. Contact a member of the team to discuss options for the property at: home@letchworth.com.

When considering a rear extension or a new rear outbuilding, PV panels could be factored into the design.

Modern Character Area

Please note that rear slopes or rear outbuildings would be the preferred locations for a PV installation before side/front facing roof pitches are considered.

The installation of Photovoltaic (PV) Panels is usually acceptable on any roof pitch in the modern character area, providing that:

Acceptable installation in the MCA

  • The design of the array is tidy and balanced with rectangles and/or straight lines.
  • The colour/design fits subtly into the site of installation and is as complementary to the street scene as possible.

Unacceptable installation in the MCA

  • The panels do not overhang the roof line on any roof pitch.

Insights from ASBP

“PV panels can be energy intensive to manufacture but accuarate embodied carbon data is variable. Roof mounted solar is often lower embodied carbon than ground mounted solar as less material is required to structurally support the panels. In addition to this solar panels can substitute roof materials, further reducing embodied carbon.”

Insights from People Powered Retrofit

“People Powered Retrofit conducted a survey and retrofit options study of a typical home in Letchworth. One of their modelling scenarios (see scenario 3 in this report) found that adding a 4 kWp solar PV system would cost around £9000 and would help to both reduce energy bills for the occupant and support the decarbonisation of the electricity grid.”

Case study

How Beth and Martin cut costs and carbon with an EV and solar panels

A solar panel case study from the Energy Saving Trust.

Read more

Links to further information

Image credits – TBC

This guidance is part of Roofs, Ceilings and Loft Spaces

See more guidance notes on this topic below:

Click to go back to the Interactive House

Or see the full directory of retrofit measures.