Can any one help? I purchased a solar powered PIR security light, with the intention of putting it inside my kitchen window. The PIR would be inside the window, but this does not work.

When I go outside to activate the light, it does not work. When I go inside to run my hand across the sensor, it works.

Will a PIR unit penetrate glass, or am I barking up the wrong tree?

3 Answers 3


Passive infrared sensors (PIR), use Infrared (IR) light to detect motion. Unfortunately for you, infrared light does not travel through glass so well.

  • Especially if you have that nice new highly energy efficient e-glass. And man sakes alive, walk though the reflection one sunny morning at sunrise to feel the reflective efficiency. Mar 29, 2014 at 1:13

This tree, not the one you should be barking up, is.

PIRs do NOT work though glass. Put it outside.

  • This particular pir unit with led lights has not got a very good IP rating any idears
    – user20714
    Mar 28, 2014 at 17:32
  • 2
    Without knowing which particular one you are talking about (there is no link, model number, etc. given), if you can mount it up high under the eaves (or other roof overhang) that helps to keep it dry - that's assuming you can put the solar panel part somewhere that it can get sun (easier if separate, harder if attached.) Or, return it and buy a better one. Sometimes cheap is just cheap, not a good value.
    – Ecnerwal
    Mar 28, 2014 at 17:39

Most PIR scensors manufactured now, especially devices that are used soley as alarms , are equipped with more than 1 type of sensor that it will use to determine whether or not to ALERT or not. And yes this is true for most every model ive seen in the last two years, including the "cheap ones". For instance I'm sure you have heard of the driveway alert system as seen on tv. Even this inexpensive device uses two methods of detection using its infrared capabilities...motion AND change in temperature. This is an excellent feature because the sensor must detect both simultaneously in order to alert you. This will cut the chances down considerably. Especially after you do a little homework, mixed with a little trial and error, and get it placed in the perfect spot. I have a very similar version of the driveway alert system. The ONLY difference is my receiver, or centralized part that IS the alarm can have an unlimited number of transmitters, which are the devices that actually senses motion and temp change. And yes these are cheap and EXTREMLY ACCURATE!! So accurate that a warm blooded animal has NEVER walked within range and it not alert me about it. And they detect through through tree lines, bushes, and other places wher someone would try and hide. The infrared sensors are $9.00 each and receivers are $15. Consider this, budget permitting, purchase 2 receivers, placing one to alert using the "ding dong" mode and use it to program sensors you will place outside. They are 100% waterproof. I have sensors that have never been protected from any of the weather Arkansas could throw at them for 2 yrs plus that work as well now as the day I bought them. The other receiver should be set to the MUCH MORE uninviting sound labeled "alarm". Use those sensors programmed to it inside your home. Remember this, a false alarm is usually a error in placement of the sensor. Read the instructions to find the max range of detection, and angle of detection. Then I suggest pulling up google earth. Go to view your property and use the ruler to determine the best placement. The ruler measures distance and angles. Its the best way ive found for camera placement as well. Works great especially when you want 360 degree home protection which is difficult enough to do depending on yard size, landscape, shape of home, ect...You certainly will want to maximize your equipment's abilities based on specs included in instructions. A birds eye view of your home and surroundings will take the guesswork out of determining effective placement. Simply use the ruler to draw the lines for your devices angle of field of view, drawing the line out to its max distance of detection. Everything within the lines will be the detection zone. Use a couple dif colors for the lines should you use multiple devises so not to get confused. Hope this helps those of you interested in home and personal protection. Feel free to ask if you have any other questions on this subject.

  • 1
    Can you break this down into paragraphs?
    – SDsolar
    May 6, 2017 at 18:41

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