What is tilt? How can I estimate my rooftop solar system's tilt?

What is tilt? How can I estimate my rooftop solar system's tilt?

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The importance of tilt for your solar PV’s power output

Understand how the angle of solar panel influences output and which optimal tilt angle should you consider.
What is tilt? How can I estimate my rooftop solar system’s tilt?

Getting started with solar forecasting data can be a bit daunting for the newcomer, as there is a stack of new terminology to learn.  To help you better understand, let’s discuss tilt as a starter topic.

Understanding Tilt

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.


The image above shows samples of various tilts. (See 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. Most often, PV panels will be mounted directly to the roof surface, so if you can estimate the tilt ('pitch') of your roof, this is the value you can use. There are many ways to do this and it will depend on the tools and methods you have. You can do an in-depth online search to check the best option for you.