Making the Business Case for Solar Lighting

Solar street lighting is here to stay. Not since the adoption of LED technology has their been such a dramatic leap forward in street lighting technology.

As we wrote in a recent ILP Journal article, the advances in solar technology mean it is now a viable and realistic solution here in the UK.

However just because solar lighting is shiny and new, it doesn’t mean it should be adopted without question. It’s important for lighting engineers to be able to make a clear and well reasoned business case for the use of solar lighting over conventional wired solutions.

Whilst solar lighting offers a number of intangible benefits such as improved resident pride at the used of a green solution, this article will focus on tangible results.

These are the hard numbers that will help all involved in the specification and installation of lighting achieve buy in for their solar lighting project. The benefits we will calculate are;

  • Installation cost savings
  • Running cost savings
  • Reduction of Co2 emissions

To help simplify the process of calculating the savings permitted by using solar lighting, we’ve created an easy to use spreadsheet. To download it, simply click on the button below.

Solar Business Case Spreadsheet

Installation Cost Savings

Choosing solar lighting over conventional wired units allows for an immediate cost saving thanks to reduced installation costs.

This reduction in costs is permitted because solar lighting means;

  • No trenching
  • No cutout
  • No mains power connection

To calculate installation cost savings, you can use the following formula.

Installation savings = N x (CC + MC) + (TC x MT) – (DUC x N)

N – Number of units to install

CC – Cost of cutout

EC – Cost of mains electricity connection

TC – Trenching cost per metre

MT – Metres of trenching required

DUC – Difference in unit cost

The installation cost saving can be easily calculated by downloading our Solar Business Case Spreadsheet below.

Solar Business Case Spreadsheet

Reduced Running Costs

As solar lighting draws all of its power from the sun, there is no ongoing cost for energy. The yearly cost saving this presents can be calculated using the following formula.

Annual Electricity Cost Saving = x 365 x C/1000

N – Number of units to install

W – Output wattage

– Hours of illumination per day

C – Cost (in £) per kWh – Average of £0.14

Solar Business Case Spreadsheet

Annual Emissions Savings

In June 2019, the UK became the first major economy to pass laws to end its contribution to climate change. The legislation requires the UK to bring all greenhouse gas emissions to net zero by 2050.

As this deadline approaches, the reduction of emissions permitted by the use of solar lighting products will become increasingly valuable.

To determine the yearly reduction in Co2 emissions, use the following formula.

Annual emissions savings in Kg = N x W x W x 365 E/1000

N – Number of units to install

– Output wattage

H – Hours of illumination per day

E – UK grid emissions per kWh (currently 0.367 Kg)

You can easily calculate yearly Co2 savings using our solar business case spreadsheet. To download, simply click the button below.

Solar Business Case Spreadsheet


Solar CPD Training

This online CPD course is designed for lighting engineers, contractors, designers and architects. You will leave the course with a firm grasp on the different components of a solar street light, how they work and how best to make use of solar technology.

Solar Install Savings Calculator

This tool can be used to compare installation costs of  wired and solar lighting schemes and to calculate the installation cost savings available by using solar technology.

Solar Yearly Savings Calculator

This tool makes the business case for solar lighting by estimating the yearly and lifetime cost and emissions savings permitted by choosing solar lighting units instead of mains wired units.





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