What effect does tilt angle have on solar panels?

See what happens to the power output of your solar panels when you change the winter angle of the tilt from straight at the lower winter sun to a lesser angle, all the way back to flat. The volts don’t change all that much, but the current output drops dramatically, greatly reducing the output of your solar power system. Includes tips on how to decide what angle to tip your solar panels to for your DIY solar system.


  1. Lat + / – say 10 degrees ?
    3dB angles ? 1/2 power
    a quick plot would be of value, angle versus power out
    so we can decide how fussy to be

  2. I have a question.
    I am completely new. I have a solar panel system in place. Solar charge controller is charging batteries, everything is perfect.
    Now, I also have my inverter hooked up to the batteries.
    I need to know if I can turn the inverter on? Can I leave the system charging AND turn on the inverter and use the batteries at the same time?
    I'm told the solar charge controller takes care of all that charge/discharge stuff. I just don't want to destroy my system the first time I try to actually use the batteries.

  3. Is there some way to get a reflection on the sides. Attaching something. Then have a panel underneath a panel that captures energy from the reflection.

  4. Hi: i am at 42ºN and 8º W (-8º) Porto,Portugal
    —–What are the best angles: N-S and E-W
    —–Do the optimum angles vary throughout the year? Thanks.

  5. 121020/0535h PST. That was a fantastic practical presentation on how the angle plays a very major role in enhancing maximum power ( Amps) from PV Cells array; (corresponding to the Sun rays falling on the Array). I have 2 AstroPower AP-100 (US manufactured ) PV panels rated 16.1V @6.2 Amps each in parallel configuration.
    Before mounting them on the garage roof, the same were placed temporarily; slanted, on the lower deck.
    My OP was 13.80V* @ 9.2A* reading from VICTRON MPPT Charge Controller; charging 4S LiFePo4 cells @ 50 Ah each.
    The cells Bulk charge level was ok, Absorption was ok and soon reached Float level.
    Later I relocated the PV Panel FLAT on top of the Garrage on a N~S location. To my surprise the Current dropped down to 6A and further down to 4.3 A as the winter set in. Now I understood how much the ANGLE plays a major role in enhancing generation of current from the Sunshine. Thanks, once again to your presentation, that taught me about the importance of Angle. I will tilt the PV cells @45 degrees N/S on Saturday 121220.
    FYI there were several YT presentation on Solar Panels etc etc. But none spoke about the important factor of Angle and its role to generate maximum power. You have done it, Ma’am.
    Take care and be safe. 73s…

  6. "November 20 very near winter equinox" or is it solstice? Love your videos. Most informative and welcomed.

  7. Had watched videos about Solar farms, and most had a fixed tilt angle. I guess its not worth the effort, or newer panels are not as effected. hmm

  8. Short answer:
    1. If connected to grid, angle does not matter as much.

    2. If off grid, angle control is what you want.

    3. If you want to squeeze it all amd have time to install and maintain PV's on a flat area then go for it.

  9. Just do this : Go to https://www.suncalc.org and find your location Latitude and Solar Declination Angle. Now your Solar Panel angle should be Latitude-Declination(+ve value means face towards South and -ve value means face towards North) Angle from ground facing towards Sun.
    And just use your Android or IOS app to know the angle of solar panel.

  10. This comment section is probably dead but, How do I calculate the change of efficiency of a panel based on the irradiance? Like, in the video, she moves the panel down, and the irradiance value plummets. Is there an equation to determine how that number effects the power output?

  11. I trust that Amy is showing us the real numbers. However, here I am 5 years later reading many articles that make strong arguments that angle doesn't matter much – like 2% (instead of 20% or more). Have panels become that much more adept at capturing photons from atmospheric scattering? Sample article: https://www.thesolarnerd.com/blog/optimal-solar-panel-tilt-most-calculators-are-wrong/ and the link to the US Department of Energy calculator: https://pvwatts.nrel.gov/pvwatts.php
    Maybe the trees around Amy are blocking the scattered light?


  12. It is really helpful to have a quantified demonstration of this effect. Many thanks for posting.

  13. Now panels ar cheap, angle doesnt matter, just put up more panels, cheaper than tracking system.'

  14. Perfectly answered my head scratcher about why my 310w panel on my flat roof is hardly doing anything!! 🙏🏽

  15. Hi Ammy. I'm looking for a diy single axis sun tracking circuit which can controll linea actuator, simple circuit which I can make my own. Thanks Amy for the informative videos.

  16. My question not connected to this video,….can I connect my car(RV) generator(altarnator) to my solar charge controller ¿?

  17. I do not have mine at a tilt, they sit flat on my RV and they work great even in the winter. Just gotta keep them cleaned off.

  18. Like your angles IV been watching mynes as early daylight and is very shaded I've two off grid one is ok and a bigger is showing signs from portable set up , what inverter, so the mppt is slack and battery amp slack do one of these doesn't set to charge battery as I liked but crashes alot , I've the amp wires to track if batteries r alright it is slow but will test it this way and did consult angle solar panel ,, to remove sun's rays going alot over where roof is and been 30 minutes just when it's windy days etc there's alot change so when it's hot full on it can also but most sun rays are in the aim of angles , as natural lightness be solar DC , and couple more things to look at inverter and charge controller as panel is supposed to be set in angle therefore it is one problem the inverter has is it beeps alot so no way of telling what's not or is doing the continued power in turn the system was shut down I turn on and it either dead or runs till nothing suppose to know something I knew nothing till almost a year ago frustrates the high thing we all try free power just didn't know it works out so trying angle it works out 60 amp and at times you get 6 minutes or 6 seconds

  19. When the angle of the sun is steep, the panels get cooler, which enhances the output. This demo won't show panels cooling down. However, the glass becomes more reflective.
    I believe the output is pretty close to the cosine of the incident angle:
    0 degrees = 1
    10 degrees = 0.985
    20 degrees = 0.94
    30 degrees = 0.866
    40 degrees = 0.766
    45 degrees = 0.7
    50 degrees = 0.64
    60 degrees = 0.5

  20. Huge difference, I have two 325w panels, four 6v 225ah batteries hooked up to a chest freezer, when the compressor was on, the batteries dropped to 12.4v(panels at 30° angle), with the "Solar Tilt" app (Playstore) I found the new angle 41° voltage stays at 13v now with the compressor on.

  21. Thank You for the video. It was very informative concerning angle of panel to the sun. I had not seen it done this way where there is cause and effect registered instantaneously. Very good. I will be watching more of your videos.

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