Getting started with solar forecasting data can be a bit daunting for the newcomer, as there is a stack of new terminology to learn.  In our aim to make solar data easy to understand, I've put together a short article on tilt, to help you get started.


The tilt of your solar PV system is a measurement of how far your PV panels are from horizontal.  If you have a horizontal (lying flat) tilt, you have a 0 degree tilt. This would mean they are pointing directly up into the sky.  Conversely, a 90 degree tilt is where the panel would be completely upright, pointing towards the horizon. Most rooftop solar PV systems are somewhere in between - usually from 10 degrees up to 40 degrees. 

Above: Examples of various tilts (use the black text values)

Why does Tilt matter?

The tilt value is important for determining an appropriate magnitude of your solar PV system's power output. Flat lying or vertically oriented PV panels will produce less power across the day than those which are more moderately tilted.  The most 'optimal' tilt for year around energy generation is 'latitude tilt', meaning the tilt of the PV system is equal to the absolute value of the latitude it is located at.

Estimating Tilt

To produce an appropriately precise estimate of tilt, you'll want to measure it within + or - 5 degrees.  There are many ways to do this, and which is best for you will rely on the tools you have available.  Most often, PV panels will be mounted directly to the roof surface, so if you can estimate the tilt ('pitch') of your roof, this the value you can use.  Given it can be a bit dangerous to access some rooftops, we won't be suggesting how you do this directly.  A Google search will give you plenty of options!

Did this answer your question?