Solar Power??

Projects General Guidance
1

Hi Everyone,

I have an idea for a power supply for my Arduino Lenerdo proj:

I want to have:

11V solar panel
diode (block current from battery to solar panel)
cap
rechargeable battery
Arduino power jack

I want to use this as the power supply, from your experience, do you think this is a feasible and reliable solution?

Thanks a lot

Cookie

2

11v panel? Most are nominally 6 or 12v. However the voltage open circuit goes a lot higher. Please give a link to the panel you have in mind.

What do you want to run?

Weedpharma

3

cookie89:
Hi Everyone,

I have an idea for a power supply for my Arduino Lenerdo proj:

I want to have:

11V solar panel

What rating Solar panel?
How many hours per day Solar do you get in winter?

rechargeable battery

What type of battery?
What voltage
What MaH rating?

Arduino power jack

depends on voltage from battery pack I think.

I want to use this as the power supply, from your experience, do you think this is a feasible and reliable solution?

Thanks a lot

Cookie

Really depends on answers above

4

You need a solar panel that can produce more energy (watt-hours) than is required by the Arduino and the losses in charging and discharging the battery. (The voltage of the solar panel is only a part of the required information)

This JRC web page may help you estimate the available solar energy.

...R

5

Hello everyone,

Thank you for your replies.

I plan to have the following:

9V solar panel:
http://www.sayal.com/STORE/View_SPEC.asp?SKU=232360

9V rechargeable battery:
http://www.sayal.com/STORE/View_SPEC.asp?SKU=239727

Also, can anyone provide some insight to calculating the total power used by the Arduino?
The current load is:
-5 flex sensors
-8 switches (on/off)
-1 MPU6050
-1 HC-05 BT module to transfer data to Android phone

Thanks in advance,
much appreciated,

Cookie

6

each device listed has a data sheet.
the data sheet will list the power at full operation and in stand-by, and maybe even in sleep.
if you turn the device off, the power is zero.

what you need to do is too create a simple spreadsheet of these.
add in the amount of time that anything might happen to allow for energy per hour.

put together what you can.

as for a switch, if you use a 100 ohm resistor, or a 10,000 ohm one, you select the power it will consume when in use. for battery power, might want to use a momentary switch.

7

Aright,

I will do that, thank you.

Also,

I'm kind of limited on space as regards to the solar panel.

Is it possible if I can have a smaller solar panel ie. 9V to recharge a 9V battery?

I understand that ideally I should have a higher voltage solar cell to recharge the 9V battery because of charging losses, however I'm limited on the size.

Thank you

8

ideally I should have a higher voltage solar cell to recharge the 9V battery

Actually, you have no choice. It must be higher.

An excellent tutorial on solar-powered Arduino is here.

9

So there's no way I can use a 9 voltage solar panel to recharge a 9V battery?

If that's the case,

Can I use a smaller solar cell ie. 9V to charge a super capacitor (replacing the battery)?

Thanks

Cookie

10

Yes.

11

Actually,

My initial idea was to obtain a 9V solar cell :
http://www.sayal.com/STORE/View_SPEC.asp?SKU=232360

and a 9V rechargeable battery:
http://www.sayal.com/STORE/View_SPEC.asp?SKU=239727

However, I know this is not exactly reliable due to the charging losses, but the objective of the solar cell is to provide emergency use ie. when battery is low. The main source of recharge will be from actually charging the battery through a wall charger.

Or, will a super cap be more efficient in my design vs the rechargeable battery?

I really appreciate the help.

Sorry about my lack of knowledge since this is my first project.

12

you need a higher voltage. cannot alter that.
and your solar cell is rated for maximum. you will get less if it is not pointed directly at the sun on a cloudless day.
any early morning, evening, or clouds will cause less power.

however, there is a thing called a buck converter to convert your voltage to a higher voltage. you loose amps, but since you only really care about watts, the other numbers are not too important.

13

however, there is a thing called a buck converter to convert your voltage to a higher voltage

That would be a boost converter.

However, solar cells don't work well with boost converters. As the voltage drops due to low light, the boost converter tries to draw more current, and the whole system takes a nosedive.

14

Hi Guys,

Quick question,

I calculated my total max. Power consumption to be 5.121W

This is for:

8 switches
5 flex sensors
1 MPU6050
1 HC-05

Thanks

15

What is the question?

16

cookie89:
Hi Guys,

Quick question,

I calculated my total max. Power consumption to be 5.121W

This is for:

8 switches
5 flex sensors
1 MPU6050
1 HC-05

Thanks

But your battery only can run for 15 mins and Solar cell can only supply 1.35W

Edit:

Solar powered Arduino by Nick Gammon

17

seems you are on the low side of the box today.
too low a volage to charge and too little power to deliver.

as for the ability to charge a battery with lower voltage, it is a reverse joulethief that might help.

as for power draw,
HC-05 : 8mA
Can work at the low voltage (3.1V~4.2V). The current in pairing is in the range of 30～40mA. The current in communication is 8mA.

switch should be near 0 except for the occasional momentary press of the button.

flex sensor would be from a volae divider of 10k to power and flex to ground
so you have a 20k minimum resistance at ??? 5v ?

the MPU-6050 : Gyroscope + Accelerometer + DMP 3.9 mA

so, 8mA + 3.9mA + 0.005 per flex sensor....

since you never clued us in to the actual project, we can not even offer suggestions to reduce power consumption.

if you are living on the equator, you get more hours of daylight to charge the battery.

18

Sorry guys, I'm very inexperienced. I'm trying my best to implement it.

I have recalculated my power consumptions to be:127.75mW

HC-05 consumes the most power at 82mW (worst case for connecting)

I'm clueless now about how to design the power supply.
The solar supply seems to be out of the question now...

Should I place multiple 9V @ 250mA batteries in series?

Thanks,

19

cookie89:
I have recalculated my power consumptions to be:127.75mW

Round it up to 250mW to give yourself a safety margin

How many hours per day do you need that amount of power. W x hours = Wh = energy

...R

20

cookie89:
Sorry guys, I'm very inexperienced. I'm trying my best to implement it.

Welcome to the world of self-taught hobbiests and the Arduino.

you have brought us the classical X/Y problem. This is not criticism, just observation.
You ruled out things and assumed things, and then presented a small problem that is the result of not addressing the actual task.

if you were to ask:
I am new to electronics and the Arduino and have an idea for a project, I have no experience in making circuits and
I have this, this, and this.....
I want to do this... with them and would like to run it all on solar power.
can you offer suggestions ?
this thread would be much different.