Hi

[hellrider666]

This is Chris aka hellrider from New Delhi, India. I am a solar lover and would love to discuss the innards of the science behind solar.

I am also having a trouble with my mobile solar panel charger.

I have the following setup:

A total of 5 * 6.5 volt solar panels connected in parallel
A powerbank (15000 mAH)
A phone to test charging (android)

Please check the image of the setup I have made. Under normal test conditions when I connect the multimeter to solar panels (positive and negative) I get the following reading:

Voltage: 6.6 V
Amperage: .6 amps

The individual panels are rated for (6.5V 150mAH) so when I connect in parallel the amperage adds up while the volts remains the same (I hope the logic is correct).

My guess from reading over the internet and on instructables is that any 5-6 volt .5 - 1 amp input should charge a mobile device or a power bank.

But after testing the setup, I am not getting any charge in my phone (which is roughly half empty).

I dont know where things are going haywire.

Any help would be appreciated.

Thanks
Hellrider





IMG_20160822_234655.jpg IMG_20160822_234703.jpg IMG_20160822_234725.jpg IMG_20160822_234739.jpg

[SunEagle]

First off I am not sure I understand what you have. Each of those pictures show what looks like 5 "cells" that are wired together to make a "panel".

Sorry. Not thinking straight. Please answer my first question and then maybe we can help you

[hellrider666]

Each of the five cells are giving an output of 6.5v as there are 12 small cells of 0.5v each connected in series to make one big cell. I bought five of these cells and connected them in parallel.
Hope I am making sense.
Thanks for replying.

[inetdog]

What is the output voltage of the panel (not cell) string without any connection to the phone?
What is the output voltage when connected?
If they are the same, then you have not wired the connection to the phone correctly OR it requires more than 6.6V to charge properly. Some phones may also disconnect their charging circuitry if the input voltage is too high. You could try dropping the output voltage with a forward biased diode in series with the output wire.

[hellrider666]

I havent tested that yet.
Maybe I can perform a test tomorrow and get back to you with some pictures. I have a powerbank of 15000mah capacity that i am trying to charge. If my phone doesn't charge due to disconnection of charge circuitry then maybe powerbank should charge.

[SunEagle]

Each of the five cells are giving an output of 6.5v as there are 12 small cells of 0.5v each connected in series to make one big cell. I bought five of these cells and connected them in parallel.
Hope I am making sense.
Thanks for replying.

Thank you for the explanation. The pictures got me confused.

So each of those 5 have a 6.5v and 0.15 amp output( which seems very low). Wiring them in parallel gets you a "system" of about 6.5 volts and about 0.6 to 0.75 amps?

That is probably not enough amps to charge your android. My slow android charger is rated about 1 amp and it takes hours to charge my cell phone. My fast charger is about 9volts at 1.6amps

[hellrider666]

Can I add more panels in the system (in parallel) to increase amperage to around 1.5 amps ? Will that work?

[SunEagle]

Depends. I think it is more than just the correct amount of amps and volts needed to charge an android phone. You will certainly need a constant Volat and Amp output that sunlight will not necessarily provide you.

[jflorey2]

But after testing the setup, I am not getting any charge in my phone (which is roughly half empty).

If the phone is a USB charger, you need the correct voltage AND the correct treatment of the D+/D- lines. If you short D+ and D- together the phone will usually recognize the attached device as a dedicated charger, although in some cases you'll get a "charger not supported" message because the manufacturer wants you to use their own charger.

You also need to regulate the voltage. A low dropout LDO will probably be ideal here. The MIC29300-5.0WT would do it. (You'll also need some capacitors as detailed in the data sheet.)

[hellrider666]

I looked up the data sheet for MIC29300-5.0WT.
I struggled to understand all the information so basically what I understand is that If i have this in my current circuit, I should be able to boost amps from 0.5 to 1.5 using this voltage regulator (also my voltage would drop)
The diagram for 3 pin MIC29300 has got me a little confused (do i need to add capacitors as well)

Can you suggest some tests that I can do maybe in order to resolve the problem.

[jflorey2]

I should be able to boost amps from 0.5 to 1.5 using this voltage regulator (also my voltage would drop)

No. Your voltage will drop to 5 volts. Your current will NOT increase. That is a characteristic of linear regulators.

The diagram for 3 pin MIC29300 has got me a little confused (do i need to add capacitors as well)

Look at the 'typical application' circuit and follow that schematic.

If you cannot read a schematic, then you will not be able to do this, and you will likely damage your phone in the attempt. In that case I would recommend off-the-shelf products like the Gopole solar charger.

[hellrider666]

Hi, After much reading about and scratching my head, I agree with you. A LDO voltage regulator is ideal here. I am planning to check my local electronics market for a pair of 29300's, a 10mF capacitor, and try to test them using a breadboard with the load connected.

I may also buy some 7805's, LM2940's and resistors (100ohm) and capacitors (10mF) as spares for further experimentations. Although I couldn't understand everything on the datsheets of those semiconductors, but I hope I will not fry the battery of my phone as long as you are there to guide me.

I will add some more cells to have the following config:

6.6 V and 2 amps system input..... (an LDO connected) that gives 5.0V with 2.0 amps output to the phone battery.
The 29300 will be grounded by a 10mF capacitor.

Is there a way to insert an LED so that I know the system is juiced up?? Should I connect it on the positive output of 29300 that goes to my android device.

Also, as USB chargers have D+/D- cables, should I just short circuit them or connect some resistors and connect it with the positive line as depicted in the image below. I hope I can get this project working by today as I am having sleepless nights becoz of my dumbness.

[bcroe]

I see 5 cells, each with a couple solid pieces of tabing running across the front. That tells me, each is a single PV cell
capable of about 0.5V. They look like 3" by 6" cells, capable of about 4A. Unless divided in the middle. Bruce Roe

[hellrider666]

these are not 5 cells. Each cell is made up of smaller wafers (each wafer is 0.5 volts and .130 amps) connected in series.
If you look closely, you will find there are 12 such wafers connected in series, thats why my multimeter is reading around 6.5 volts in bright sunlight test conditions. I will share a picture today when I test it again.

[SunEagle]

I see 5 cells, each with a couple solid pieces of tabing running across the front. That tells me, each is a single PV cell
capable of about 0.5V. They look like 3" by 6" cells, capable of about 4A. Unless divided in the middle. Bruce Roe

That is what I thought I saw in the pictures when I made my first post, but the OP states different. Hard to know exactly what they are unless we have more info.

[hellrider666]

SunEagle each of the five cells are made up of smaller cells connected in series. They are tabbed and encapsulated (ready for use) . All that was needed was to solder the end terminals and test the system. thats what I did.

I connected all of them in parallel (to increase to amperage) and in bright sunlight I was getting 6.5V and .65 amps (I think I should buy more of these and connect them in parallel to get amperage up to 1.5 amps atleast.
The entire system has costed me as follows:

5 pieces (1.4 USD per piece) = $7
Soldering gun = $2
Flux and wire = $1

Total = $10
If I buy more cells (5V and .130 amps per cell) I would need atleast 10 more (that is equal to $14)
So my total investment would be around 10+14 = $24 USD

There are market options such as these:

http://www.goalzero.com/portable-solar-charger/

but they are not economical are they ??

Thanks for all your valuable suggestions.

I was wondering what "constant amount of voltage and amps mean" I get direct sunlight and I dont tinker around the panel. Even the multimeter doesnt show fluctiations of voltage when the panel is lying in the sun and connect under test load (battery bank or phone)
I am hoping I can solve the puzzle by adding more cells in parallel and increase amps and test again.

[hellrider666]

jflorey2 check this image. INstead of 9V cell, I will use 6.6V solar system. will that do the job? circuit.jpg

[jflorey2]

You'll need a bulk capacitor after the regulator and a small capacitor before the regulator. (10uF bulk and .1uF input cap are common but of course check the data sheet.) I would recommend just shorting D+ and D- together.

I would also recommend trying to drive something other than your phone initially. A 5V incandescent lamp (a flashlight bulb between 4.5 and 6 volts) for example will take a moderate amount of power. And if you damage the bulb, it's a lot cheaper to replace than your phone. When it is connected use a meter to verify that your voltage and polarity are correct before trying it on the phone.

[hellrider666]

Thanks jflorey2 I will get the items and test them very soon.

The bulk capacitor will be 10uF and the small capacitor should be (.1 or 1 uF) ?? just want to be sure!!
thanks a ton.

[jflorey2]

Doesn't matter too much; .1uF is pretty standard. Again CHECK THE DATA SHEET for the part you are using.

[Mike90250]

I just love circuit design via text for the very first project.

[hellrider666]

jflorey thanks mate for helping me kick my brains out on this small project.

The panel is working (I am using 7805 voltage regulator as MIC29300's are not available in markets and ordering would take atleast a month to reach me)

The panel is giving a steady output of 5.0 V and .6 amps. I have connected the capacitors as you mentioned. The phone shows that it is charging.
SunEagle - I will add more cells in parallel to increase amperage once I am sure the system is stable.

I also need to perform proper testing tomorrow in bright sunlight and post my results. For now, here are some eye candy.

I post some images with multimeter tesing the panel under load and without load.

Thanks Suneagle Bcroe and jflorey ( I couldnt have done it without your support)

Also, I find it funny that instructables doesnt have even a single solar panel for mobiles that talks about voltage regulators or capacitors in the circuit diagram.
Anyways I might me missing something but glad to see the charging sign beginning to light up my phone.

IMG_20160824_162804.jpg IMG_20160824_162822.jpg

[hellrider666]

Hi,

After testing the solar panel, I have some questions and concerns that i would like to share with you.

First the results:

Image 1 : Voltage (without load) (direct on the +/- leads of the panel) IMG_20160825_124837.jpg

Image 2 : Amperage (without load) (direct on the +/- leads of the panel) IMG_20160825_125002.jpg

Image 3: Amperage (without load) (after the 7805 regulator/ just before +/- connect to USB cable) IMG_20160825_125728.jpg

Image 4: Voltage (without load) (after the 7805 regulator/ just before +/- connect to USB cable) IMG_20160825_125822.jpg
Working just as intended (bringing the voltage down to 5.0 V)

Image 5: Voltage (with load) (after the 7805 regulator/ just before +/- connect to USB cable) IMG_20160825_125947.jpg
Noticed the voltage drop once the load was connected. It was supposed to be 5.0 V but came down to 4.5V. (Phone shows charging but doesnt charge according to battery percentage indicator in the phone)

Image 6: Voltage (with load) (just before +/- connect of Solar panel) IMG_20160825_130108.jpg
Voltage was initially 6.6V (without load) but came down to 6.3 (With load) (this is measured on the +/- leads of the solar panel before the current passes 7805 or any capacitors.


I would like to know a few things here.

1) Phone doesn't charge (it just shows that it is charging) when current passes through the circuit to the USB cable but phone charges when I remove the circuit and feed 6.6V and .330 amps? I dont want to fry my battery so removed it right after getting the test results.

2) I cant find LDO in market and the LDO available are 6V only. Can I use a simple 5V diode instead of voltage regulator ? if yes then which one (schottkey/zener etc.)?

3) Can you please look closely at the multimeter (when I am testing amperage) and tell me if the setting and readings are right ? (I am not sure if I am testing amps correctly) (I am sure about voltage tests though )

Well I have more silly questions but I guess ill keep them for later. I hope I can make this work as I am off to a remote place in two weeks.

Any help on this will be greatly appreciated.

Thanks
hellrider

[SunEagle]

Well my first question would be. Are any of those measurement being performed outside under the Noon sun?

If not then I would say that any light that may be reduced by shadows or the sun not being directly overhead or using inside lighting or the cells not aimed all in the same direction would generate voltages and currents that may not be correct.

[hellrider666]

These measurements are all under noon sun.

[J.P.M.]

These measurements are all under noon sun.

What's the angle of incidence ?