Question

I have a project where i have to include solar cells and piezoelectric transducers in an umbrella.

They will be used to transform solar energy and energy from rain respectively into electrical energy. (stored in a lithium battery)

I would like to know how i should build up the circuit. As in:

1. should i connect the solar cells in series?

2. How do i connect the piezoelectric transducers? what type of rectifying diode i need for this experiement.

3. What calculations i can use to show that the energy harvested by the piezoelectric transducers will be very little?

4. What calculations i can then use to show that to have more energy i make use of solar cells?

Answer 1

Very interesting idea !

As multiple solar cells can be used to increase net volatge and current of the system. Connecting solar cells together can seem like a daunting task when you first start to look at how it should be done, but connecting multiple solar cells together is not that hard with a little thought. Wiring solar panels together in either parallel or series combinations to make larger arrays is an often overlooked, yet completely essential part of any well designed solar power system.

For high voltage cells should be connceted in series and for high current cells should be connected in parallel

as in this project both are essential (Net ampere value matters a lot in battery charging)

It is suggested to used hybrid combination (parallel + Series)

For exmaple if we have 4 cells (panel ) make two line by connecting 2 cells in series and the connect them in parllel

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2. Connect Piezoelectric in parallel to solar combination ( it is very important to note that solar pannel and peizoelectric will work on different concept, As Peizoelectric will work during rains when solar light is not available and when there is solar light there will not be rain. They must be connected in parrallel so that they can operate independently )

# Don't forget to connect diode in between to netarlize the effect of source in not working condition (When solar is working peizoelectric will not work)

(Important : Piezoelectric will generate AC output but we need DC for battery changing so use a "Bridge rectifier" of diode IN4007 , A capacitor for smoothening and a volatge regulator )

3 & 4. Calculation is very simple

Use average pressure created by rain drops under ideal condtion on specific area covered by piezoelectric transducer and consider output AC power as input of ideal bridge rectifier to calculated Load volatge delivered by circuit. [Calculate by assuming 1 hour continuous rain]

Use general formula for calculation of output in solar cell

The formula to estimate the electricity generated in output of a photovoltaic system is :

          E = A * r * H * PR

E = Energy (kWh)
A = Total solar panel Area (m2)
r = solar panel yield or efficiency(%)
H = average solar radiation on panels placed on umbrella top (shadings not included) [ calculate for one hour]
PR = Performance ratio, coefficient for losses (range between 0.5 and 0.9, default value = 0.75)

[By comparing the power generated conclusion can be drwan]