Solar Panel Installation: How Tilt, Shading and Orientation Affect Performance

by Jarrah Harburn on October 3, 2011

There are a number of factors that come into play when installing solar energy panels. Some of these aspects are incredibly important in ensuring consistent maximum output over the seasons. A properly accredited Micro Generation Scheme (MCS) Solar Energy Installer is trained on the differences between panel tilt, location and orientation. However, it never pains to learn a little yourself on this important topic.

Tilt and Orientation

Panels are installed differently based on their geographic location in the world. We’re all aware that the Sun is the most critical aspect of your standard photovoltaic (pv) system’s importance. However at which angle and how direct the sunlight should be can be slightly less obvious. In the UK we are situated in the Northern Hemisphere and so for the most part, the Sun tracks through the Southern part of our sky between the tropical lines and across the equator. Photovoltaic (meaning a voltage produced from light) panels work most effectively when the maximum amount of light particles from the sun are hitting their cells at a perpendicular (90 degree) angle. With this in mind, we can generalise the sun’s movements relative to our position and ascertain the correct panel tilt and orientation.

Solar Panel Tilt and Orientation in the UK Departures from the ‘bullseye’ of the target decrease projected performance at a steady rate

The geographic location of the UK and our distance from the equator has been measured to suggest an angle of approximately 35 to 40 degrees is ideal for a solar installation. As the sun is to our South for the most part of the year, a true South orientation is also deemed to be the most effective. Utilising the chart to the right, you can see approximately how deviations from these two parameters will affect performance. The rate of performance loss isn’t extreme, so all those of you out there without perfect South-facing roofs at 35 degrees can rest assured that your systems are still going to produce significant amounts of energy, and that your return on investment is by no means in jeopardy. Generally speaking, any angle from 10 to 50 degrees and orientation from 240 degrees South West to 120 degrees South East will be performing very well. If you have any queries about your roof specifically, please get in touch with us here. We utilise impartial information to help you understand accurate returns and performances.


The sunny South West has it’s advantages, but even Scotland still receives a sufficient amount of the sun’s rays

System Location

Another aspect relates to where your property and the solar energy system itself is located in the UK. Further proximities from the equator as a general rule receive less solar radiation. Due to the various obstacles and layers of ozone between your place and the sun, the simple truth is that less energy reaches your location a solar energy system will produce less energy. It’s not something to be overly concerned with, as once again the differences are not sufficient enough to affect returns on investment in a substantial way. The image to the left details the differences from the highest regions of solar radiation to the lowest. It’s clear that whilst Devon and Cornwall possess an advantage, the remainder of the populated regions still receive good amounts of light. This again, is not a factor that should influence your decision to install solar or not. If you’re unsure, contact us today and we can send you accurate information on your proposed systems performance.


Now this is an important one. Shading affects solar energy panels significantly. Unlike tilt, orientation or location, the presence of even a small amount of shading on part of a solar energy system is never to be taken lightly. Many systems claim to possess technology called ‘Bypass Diodes’ that allow certain parts of the system to be quarantined from affecting the overall systems performance. However, the reality is that the number of Bypass Diodes alters significantly from one system to another. So whilst one system can claim to be ‘shade resistant’ because of it’s diodes, the real question is how many does it use? A system containing one or two for instance could claim tolerance to shading, however in comparison with a significant number more the systems performance would pale in comparison. The truth is that such technology can be very expensive, and whilst there are some credible options in the industry such as the Solar Edge, the real ability of a system to isolate shading incidents from significant performance loss is a complicated technical matter. In addition, the fact that the system needs to be installed before the reality can be measured means this is a consideration best weighed up carefully.

Solar Selections would recommend anyone with shading issues to take care when making decisions, as the sales pitches of solar installers can be somewhat favourable towards their own in-house solutions. Why not speak with us if you’re curious? Our free service can only help in making the right decision on your project.

Written by Jarrah Harburn

Phone: : 020 7205 2267

© 2011 Solar Selections Pty Ltd

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{ 4 comments… read them below or add one }

hoshiar December 5, 2012 at 7:58 pm

Hi how are you? I am Hoshiar, an architect from north of Iraq.
We want to ask about solar power for a poultry farm here, and we need to the best type of system (pv) you offer. We want to design a new system for a poultry farm here, if you can help me here.

Best regards
Hoshiar S. Sabir


Solar Selections December 5, 2012 at 10:27 pm

Hello Hoshiar,

Thank you for the comment, but unfortunately we operate only within the UK.

Best of luck finding a system!


Michaela April 16, 2013 at 9:12 pm

Hi there,

I just wondered, what are the angles of the tilted solar panels measured with respect to?

Best wishes,



Solar Selections May 8, 2013 at 8:26 am

Hello Michaela, I am not too sure what you mean, but when we say 30 degree pitch, this means 30 degree angle from the ground (not the roof). Therefore if a solar array is installed on a 30 degree pitched roof (from the ground) the array is considered to be at 30 degrees as it will be fitted flush with the roof. I hope this helps, if not give us a call to speak with your personal Solar Broker. Regards, Solar Selections


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