What Is The Best Tilt Angle For Solar Panels On A fixed Roof?
I recently wrote an article discussing what would be the best direction for solar panels to face. To get the maximum amount of energy in each day, the panels need to face true north in the southern hemisphere and true south in the northern hemisphere.
This gives your system the best opportunity to collect the most amount of energy possible each day, however, with the panels positioned this way, the system may produce the maximum a of energy at a time when the family least required it.
It was frequently in the best interest of most families to trade off collecting the maximum amount of energy each day for collecting a smaller amount of energy that could be used at the time of collection.
So what is the best tilt angle for your solar panels? The quick answer is, the best angle for your panels to be mounted is the latitude of your home. For example, if your home is located at latitude of 40°, then the best tilt angle of your panels would be 40°.
Because the sun is a little higher in the summertime and a little lower in the winter time, being able to adjust the tilt angle through the seasons is also advantageous. The long answer is, the best angle for your panels to be mounted depends on your latitude and the households electrical load profile.
Ideally, for panels to work most efficiently, it is necessary to have the sun’s rays hitting the panels at an angle of 90°. Because the sun travels from east to west every day and changes its height in the sky marginally every day, and significantly throughout seasons, unless you have your panels mounted on a tracker, having your panels consistently face the sun at 90° is not possible, so compromises need to be made.
A solar tracker is a mechanical construction where panels are mounted on a moving platform that continually adjusts throughout the day and through the seasons to automatically have the sun’s rays strike the solar panels at 90°. A solar tracker faces east in the morning and tracks the suns path throughout the day to the west in the afternoon.
It resets itself for the following day. Gradual adjustments are also made through the seasons usually culminating in an additional 15° to the tilt angle on the summer solstice and reducing the tilt angle by about 15° on the winter solstice.
If your panels are securely fitted on your roof then this is not an option. So what is the best tilt angle for panels which are firmly mounted on a roof? Well, that depends on your electrical usage profile. If your home is located in a climate zone that experiences hot summers, you may be in the habit of using air-conditioning frequently through the day. If your home uses gas for cooking or has a wood heater that you use in the winter time, setting the tilt angle of your solar panels higher than the latitude of its location is more advantageous as you will get more energy in at a time when it is most needed.
If however, your household uses electrical heaters through the winter time, the panels are best tilted to an angle 10 to 15° less than the latitude of its location. If you have positioned your solar panels with some facing east, some facing north and some facing west, then once again, your electrical load profile would dictate the best tilt angles of each orientated panel.
Panels facing east and west, even in the summertime, are exposed to the sun when it is lower in the sky as the sun is either rising in the morning or setting in the afternoon. The tilt angles in this respect would need to be adjusted depending on the home’s orientation so that the suns rays hit the panels at 90° for most amount of time.
Regarding the advantages of having panels mounted so that their tilt can be adjusted, the ease of being able to make the adjustment requires assessment. It’s not practical for an elderly lady to be climbing up a ladder onto a roof to make seasonal adjustments to the tilt angle of panels.
Depending upon a number of factors, including home orientation and her electrical load profile, it may not even be worthwhile for her to have even her grandson perform this function. More than 20 years ago when panels were five times the price that they are now, this may have been a consideration. It is now less expensive and far more convenient to simply add more panels to make up losses due the suns seasonal repositioning.
Solar collection would therefore peak at each equinox; most possibly when
a peak collection is least needed, however, this is a compromise that needs
to be made for convenience. >>> COMPLIMENTARY VIDEO >>>
So, what is the best tilt angle for solar panels mounted on a fixed roof? Once again it depends on a number of factors including your electrical low profile. It is however, best practice for panels facing the equator, to have a tilt angle of the homes latitudes, if possible adding 15° in the summer and reducing by 15° in the winter.
John Lynn
www.sunburbanoffgridliving.com