Solar Panel Installation - Which way is the right way?

January 27, 2021

It’s widely accepted that if you want to get the absolute most out of a solar panel it should be south facing to capture the sun as it travels from east to west.

But what if your buildings do not face south? Or what if maximising self-consumption of the solar power is more important to you than the peak output of the system?

This blog will look at the impact different orientations have on the output of a solar panel.

South

A south-facing solar array will give you a nice, rounded, bell-curve as the sun moves across the sky. Performance will build gradually throughout the morning, peaking at midday, before gradually reducing in the afternoon as the sun starts to set.

The main benefit of a south-facing system is the performance; you will see more power generated per panel. Broadly speaking, a south-facing array in Kent will generate
c. 959kW/h per kWp
 
The main drawback of a south-facing system is that the superior performance is concentrated across a few hours of the day – this might mean that some of the power is exported to the grid because you are generating more than you can consume.

East or West

An east or west solar array will give you a slightly different generation profile

If east-facing only, the system will generate most of its power in the morning as the sun is rises and makes it’s way to south – perfect if most of your power demand is early in the day and you are keen to maximise self-consumption.
 
Performance will steadily reduce throughout the morning before tailing off in the afternoon. Broadly speaking, an east or west facing array in Kent will generate c. 926W/h per kWp
If west-facing only the system will generate little in the morning before gradually building in the afternoon and peaking in the mid-afternoon. Again, perfect if most of your power demand is later in the day and you are keen to maximise self-consumption. Broadly speaking, an east-facing array in Kent will generate c. 905W/h per kWp
 
As you might expect, for both east and west facing systems, the main drawback is that the output is going to be lower than if it were south-facing.

East and West

If you have steady energy demand throughout the day, and you want to avoid midday peaks to prevent exporting too much power to the grid, an east/west facing system might suit you best.

As with the east-only system, performance in the morning is strong as the sun rises. However, rather than tailing-off in the afternoon, the ‘bell-curve’ will be flatter – yet broader – as the performance stays strong in the afternoon thanks to the west portion of the system.

Moreover, if you are considering a field-based solar array, orientating the panels east and west will allow you to install more panels per m2 than if they were orientated south. This is because south-facing rows of panels require a gap between each row to prevent inter-row shading; east/west facing panels do not require the same gap.

Broadly speaking, an east/west-facing array in Kent will generate c. 915W/h per kWp

North

Photovoltaic cells require two types of radiation to operation –
 
  • Direct – when the light from the sun is directly bearing down on a solar panel
  • Diffuse – light that is ‘bouncing around’ in our atmosphere
 
With this in mind, if your site is a heavy user of power and, critically, has shallow roof pitches (<12º), then installing solar panels on the north elevation will allow you to capture the diffuse radiation.
 
Purely from an economic perspective, if your site meets the criteria to justify a north-facing array, then the reduced output of a north-facing array can be offset by the cost of the system; broadly speaking the more panels installed on a site the cheaper (per panel) the cost of the solar pv installation.
 
Clearly you would only consider a north-facing system if you have used up all other roof space first.
 
Broadly speaking, an north-facing array in Kent will generate c. 798W/h per kWp

Summary

Subject to your motivation for installing solar panels, when it comes to roof orientation, there are no right or wrong places to install them.
 
If you want to maximise generation, south is best; if you want to maximise self-consumption, thinking outside of the box and considering east/west/north roofs might actually prove more beneficial.
 
As part of our development process, BeBa undertake detailed usage analysis to produce the most optimum design based on your motivation for going green.
 
For an initial consultation please contact us today.