IoT Hacks #2 – Using solar panels in IoT sensors

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Written by: Piotr Strzałkowski, embedded domain expert

And here we are again, bringing you more on energy harvesting. This time we’ll have a look at a specific example – how to obtain additional solar energy for a smart, battery-powered IoT sensor, which can be responsible for Bluetooth communication, temperature and pressure measurement.

Energy harvesting for IoT

Let us recall that energy harvesting covers a variety of solutions that provide the opportunity to obtain energy from the surrounding environment. What are the types of energy harvesting? As it turns out, energy can be obtained from sunlight, vibrations, temperature differences, magnetic fields, and radio waves. There are pros and cons to each of these options. But keep in mind that some of these solutions might not work for all cases.

More on this can be found in the first article of IoT Hacks series

The use of alternative energy sources in battery-powered devices (which are energy-efficient by nature) makes them maintenance-free. Plus, it allows you to implement new functionalities, too.

Powering an IoT sensor with solar energy - an example

Solar energy is the most efficient energy source. Let’s consider the following case scenario. We have a battery-powered IoT smart sensor with components that are responsible for Bluetooth communication, temperature and pressure measurements.

The amount of energy the sensor will consume depends on many factors, but for our analysis, let’s assume that communication between the sensor and the data aggregation device (transmitter-receiver) occurs:

– at a time interval of 10 seconds,

– within a distance of up to 10 m,

– in an office environment.

And so, in such conditions, our smart sensor consumes about 0.1mA on average, which, using a CR2032 battery under ideal conditions, gives us an operating time of 2000h.

With the use of a small solar panel of approximately 7cm x 7cm area, on which light with an intensity of 1000 lx falls, in about 80 minutes we can accumulate an average of 1.7J of energy. This energy allows the device to work for about 76 minutes (with an average current consumption of 0.1mA).

So the great news is that for every 80 minutes in which the appliance is in operation, we get 76 minutes extra ‘for free’. What’s worth bearing in mind is that the amount of energy consumed is almost equal to the amount of energy produced. As a result, our appliance becomes almost completely self-sufficient!

Of course, as we all know, the reality is a bit different. The light intensity is not that stable and the lights in offices don’t stay on at night, so the system has to draw power from the battery during that time.

However, if we assume that the office “runs” 16h a day, generating an adequate light intensity, our system will work 2/3 of the day for free, which will result in an operating time of 6000h on a single battery! Sounds brilliant, right?

Summing it up

As we can clearly see from all of the above, the use of energy harvesting can revolutionise our systems. Hence, it is definitely worth taking advantage of the technological advances that today’s age offers us. The only question is, what are you going to do about it?

If you are wondering whether it is possible to extend the battery life of your IoT device, or you are looking for a technology partner to create a dedicated IoT solution – get in touch with us!

 
We have successfully delivered many projects that required energy harvesting and we will be more than happy to tell you how it can be done. Drop us a line for a free consultation!

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