Outdoor security cameras from companies including Swann, Nest, Arlo, Ring, Reolink, Uniden and many others are becoming a fixture in more homes – or should be. Solar panel chargers are seen as the solution to the annoyance of constant battery recharging.
Spoiler alert – only one of the solar panel chargers on test, was capable of producing enough power to keep the camera running and charge the battery at the same time! Read on.
Solar Panel chargers 101
Before we get into Solar Panel chargers it is important to know that it is not necessarily physical size but energy efficiency that counts.
Panels/cells can be either thin crystal (cheapest), polycrystal/amorphous (mid-price) or monocrystal silicon (more expensive). Efficiencies in converting sunshine to power range up to 10, 19.3 and 24.2% respectively.
Gadget Guy found popular security-camera portable solar panel chargers range from a meagre 12-cells, 24-cells (average) to a massive 64. Assuming each cell generates similar current (amperage) the more cells the better.
But of the five panels tested the worst had 10% efficiency and the best was 17% indicating not very efficient cells, placement or power delivery.
Then there is the IC chip controlling voltage and amperage output. Because all the panels only have to power a known camera with set battery/voltage/mAh, the IC regulator is the cheapest possible to do the job – just delivering up to the stated voltage/average. In multimeter tests, two had no semblance of regulated voltage delivering from below 1V to 9V (but read why later*)
Mounting solar panel chargers
Roof-mounted solar panels work best in an east/west orientation (north facing) where the sunlight hits at a 90º angle.
The ideal tilt for Australian sun is at 32º from horizontal (imagine 1/3rd of a right-angle). Anything more or less reduces efficiency far too much. Security camera solar panel chargers are no different!
Why then do the majority of photographs show almost vertically mounted panels under eaves or on walls facing a fixed direction?
This orientation would produce effectively less than half of the efficiency of our test rig.
How much voltage and amperage do you need?
The assumption most panel suppliers make is that the camera has a ‘few’ activations per day. We dug deeper to find what each camera maker defined as a few and what power the cameras actually need.
Only Uniden was brave enough to state,
“The panel allows the camera to recharge during daylight conditions. Different weather conditions in Australia and New Zealand can affect the rate of charge to the battery.”
Uniden state about six month’s battery life – at one detection a day! That is unrealistic but it does add that the battery (on a specific model) will last a total of 650 minutes (day use) and 400 minutes for night use. It goes on, “Fully charge the camera with a wall charger first and only use the Solar Panel for long-term power. Heavy usage of your camera can drain the battery faster than the Solar panel can recharge it.”
We estimate that a camera will have at least six activations per day resulting in live streaming and recording to the cloud or a local microSD card. Using Uniden as a guide that is about a month or so’s battery life as evidenced by frequent customer reviews of all cameras. Fact: you won’t get anywhere near the claimed battery life.