CC2430 solar power

Thank you for your response,

I have some more questions jeje.

I read about the different types of solar panels.

The crystalline silicon solar cell has better efficiency compared to the amorphous silicon solar cell.

On the other hand, the amorphous silicon solar cell is more sensitive to stray light than the crystalline

solar cell.

What do you think could be the best one for a room with fluorescent tubes and which must be the electrical specifications of the solar panel?

And if you had a wiring squematic example this might prove helpful.

thank you again.

Fluorescent lights are not the best for solar panels due to their odd assortment of narrow spectral line versus the specific band gaps of the solar panels. Amorphous silicon panel will be much better than single crystal solar cells due to their better sensitive into the UV region where fluorescent light have some strong bands. Single crystal does better in the IR and therefore prefer incandescent lights.

I think I have attached the circuit diagram for the battery charger and the voltage regulator. The resistor values are set to charge a 1800ma battery at a rate of 1000ma from a 5v USB source which fits nicely with the TPS61202's 5v output.  The charger can handle up nearly 3 amps.  The max input is 7vdc.

The CCxxxx radio all consume about 25ma when full on during transmit. At 3 volts this is 75mW. For 24 hour service so you’ll need 24 75mw hours of energy. It is best solved in joules but let’s make it easy.  Let say the light is on 25% of the day and there is no window, so if everything is perfect the solar panel must produce 300mw for 6 hours.  Everything is not perfect so we will double this to 600mw for 6 hours. Therefore the solar cell which puts out ~.5 volts will need to product about 1.2 amp.

You have not said anything about the type of data the radio is sending.  The numbers above would support 24/7 streaming voice. If your use is a more typical sensor that sends data in 4ms and only once every minute the solar cell could be very small.

This is a rough analysis but the goal is to show the parameters that go into the calculation. If you will post more detail I can give you a better estimate. I do not need to the application just the parameters that effect performance.  That is: how long the light is on,  wattage of the light, distance  from the light, how long the radio is on for, how often is the radio on, and how much range do you need.  If the range is short you can run the radio at a lower voltage and save some power.

Ok i'm going to try to post more parameter details.

      My end device is going to do capture from a sensor and after 10 captures, it will send the message. This will occur only 3 hours per day. the remaining time will be in low power mode. The problem is that the rate of transmission will not be always the same because we will have a variable capture frecuency. The time between each transmission varies between 360ms and 10 seconds and this transmitt four char bytes. The maximum number of transmissions in one hour will 10.000 but this will always be less (I think the average could be 6000 or less even). 

    The light in the room to be on a minimum of 5 hours per day but this is not a factor contrasted .(tomorrow I will have the real data I hope).

    The distance  from the light is 2 meters(tomorrow I will know the  wattage of the light). 

Do you need to know something more?

Sorry if something is missing because my English is not too good.

thank you again

Berto

Ok, I have all the parameters, I think.

They are quite different from the previously posted because it has changed the location of the system.

1- The light in the room will be on 15 hours per week (2 days-4hours/2 days-3hours/1day-1hour/2days-0hours, but if necessary it could keep some hour more). Although the room is not completely dark, except at night.

2- There are 5 points of light that are no longer fluorescent tubes. They are "down-light" bulbs  with two bulbs for each point of light.

3- Each bulb is 40W.

4- The distance  from the light is 3 meters.

5-The room where the devices will be locate have 9 meters long and 4.5 wide and the disposition of points of light will be like number six on a die.

6-The maximum number of transmissions in one hour will 10,000 but this will always be less (I think the average could be 6000 or less even).  I'm wrestling with the idea of transmit every 0.5 seconds giving us 7,200 transmisions. The numbre is 6,000-7,000.

I think these are all the parameters you've said you need.

If you need something more or there is something missing I post again.

Thank you very much again.

You are helping me a lot.

Hi,

When you can send me the possible solution, please tell me what that reference voltage or solar panel need?
Because I saw that with a 2cm2 solar panel and well done but do not know.
I wonder what kind of solar panel and that would be needed to scale to size my circuitry.

Thank you again.

Hi,

Hi Chris,

I have started to design a system for that I need to select the solar panel and rechargeable battery .

I'm facing problem at the calculation of power consumption to select the solar panel.

In my design I use CC2530, some sensors, some LEDs, I have the power consumption details for above parts.

Assume that, CC2530 needs 50mA; sensors need 40mA, LED need 1 mA,

total  ~95mA. I need this much current once in an hour (Here I'm going to sense and  send the data once in an hour)..

For this i Have selected the battery  Li ion battery  ie 1020mA 3.7V 3.8wh

Now I don’t know how to choose the solar panel for the above power requirements,.

On what basis I can select the solar panel, what should be voltage range ,current range, power range of the solar panel in order recharge the above Li ion battery..?

regards

chethan

The maximum charge rate for a Li-Ion battery is typically C/2 or capacity divided by 2 (check your battery data sheet). In your case 1020ma/2 or about 500ma  plus 95ma so the unit can run while the battery is charging. We will add another 100ma for charging and regulation circuits including some margin. So this sets the current need of the solar panel at 500 + 95 + 100ma or 695ma. 

The battery actually charges to 4.2V and there is some voltage drop in  the battery management unit so assume 5V.  So the panel must supply 695ma at 5V to charge the battery at its maximum rate while running the unit.   You can use a smaller solar panel if you assume a charge rate less than the max. If you assume 6 hours per day to charge, the charge rate can be C/5 which is about 200ma plus the units current of 95ma and the 100ma overhead totals 395ma, still at 5V. This is 1.97 watts. A solar cell produces a open circuit voltage of about .6V, at .5V you can get about 160ma per square inch or about 80mw per square inch.  For 1.97 watts you will need roughly 24 square inches or  5" x 5" panel.

As stated the voltage is about .5V per cell under load. To get to the 5V you can build (or buy) an array of 10 cells in series. Due to current limitations when putting cells in series and to have a greater tolerance to shade and clouds which result in less than the .5V per cell it is typically better to use a combination of cells in series and parallel in conjunction with a boost regulator such as the TPS61202 used ahead of the battery management device above in my previous post. A good battery management device is an important safety element when dealing with Li-Ion batteries to prevent fires.

I have included the data sheet of a small array available from mouser.com as an example.

I would like to power up your equipment. Read http://www.sunpowerport.com. Can you give me an info about it? Thank you.

Berto Otero said:

Hi,

 

I want to power my CC2430 using the following structure:

 

Solar cell -> Li-Po batterie(or the best CC2430 power possible) -> End device.

ie, power the CC2430 with the batterie and using the solar cell to recharge the batterie.

I have read something about  the TPS61200 to use for this purpose, but I don't know if this is the best way or if there is another ci better.

Thank you

Berto

Berto,

I think it is better. Using your CC2430, you can have sufficient energy that you need. The   solar power   is a good choice.