Improved Wiring

Here is the improved wiring of solar panel setup. One of the picture shows 300 watts output from solar panels being fed into the batteries.

End of Episode-1

Truly speaking there is nothing in the world like a joy of accomplishment...The adventure i started almost a year ago ended up quite nicely... The target achieved was well-worth of experience with a steep learning curve... This endeavor encompasses many failures but i think their is no gain without learning from failures...

Yesterday i installed the solar system at my Karachi home and got the results as desired. Today when i sleep getting cool breeze of  Air-conditioner i can feel a bit of relief while thinking of my family at Karachi.
In near future i shall install six more panels on the same structure. This structure can withstand easily 12 solar panels total wattage up-to 1200Watts..

 The racks are under fabrication for holding the batteries and UPS stuff...

Today was a Sad Day :(

Yes a sad and awful day indeed... In a couple of month lot of set backs happens in my life... In this month some of my sweet dreams turned into scary nightmares...some of my hopes and wishes washed away... and today was another sad day...

 Alas, my laptop hard disk crashed without any signature... It showed no indication of failure.... All the family photos, my 1 year of research and lot of programming applications, my circuits and all good stuff went into holy grave :(..

Yes.. Today is very sad day ...

Solar Panel Sizing Basis

As i earlier mentioned that i shall install 1260 watt solar panels. Now its the time to show what were the basis of calculations. I have used a smart on-line solar panel system sizing calculator. The link is at the end of this post. Click on the photos to make them bigger.

Here is the stepwise sequence of load calculation activities:

STEP-1:  MONTHLY POWER CONSUMPTION CALCULATION

STEP-2: SOLAR PANEL SIZING

In this step we shall calculate the number of solar panels required based on the energy consumed by the electrical appliances in Step-1.

STEP-3: MPPT SOLAR CHARGER SIZING

I have already purchased 150DC, 45Amp charge controller.

STEP-4: BATTERY BANK SIZING

I have already purchased two batteries 12VDC 220AH.

Here is the link of online calculator:
http://www.sunsoglobal.com/calculator.html#

All in One---

This time no need of too much interconnected module with wiring :).. I have made one and only PCB for complete solar tracking. The optional  20x4 (20 character x 4 rows) LCD with 6 buttons shall help selecting and changing sensitivity, timing etc through a user-friendly Menu driven LCD interface.

The circuit contains embedded DC motor controller. I also added ICSP (In-circuit Serial Programming) interface on the PCB, so now i have no need to remove the IC from the PCB for program uploading ...

Additionally the connections are much simpler now with few spares digital and Analog pins these will be later used for some good purpose...

MPPT at my Door step...

Finally , i fixed one more piece of puzzle in this adventure...The MPPT arrived on 11th June,2012.... The world seems really to be a global village... 10days (including the week-end) from Honk Kong to my Home... Brilliant...

MPPT was in a good packing.. No scratch/dent very shiny and beautiful...Not seems cheap to me..Finned thick high quality aluminum back plate for heat dissipation and a remote meter for debugging and parameter view is an added advantage... The overall plastic body is rigid and free from any defect.. the LCD remote monitor comes with mounting bracket...The manual and Operation booklet is well written and user-friendly...The free shipment of 3.0Kg package through FedEx is another big advantage...

I paid Rs.3,021 in lieu of custom duty, so total cost of the MPPT is now: Rs. 31,033.. Its a one time investment and i think it was pretty right to invest at this time as the things going to be pricier with passing time.... The supplier was good to deal with and has a good repute as i have read the purchaser reviews...Supplier offered me  discount for more items if i purchase from his store including this MPPT in near future.. By the way i shall ask what discount he is going to offer if i purchase the same MPPT from him again:)..

Wow.. With such customer dealings, i think The China has rights to grasp the world eco-trade market....Its my honest opinion and can vary person to person...

The only thing left is now the UPS.... Lets cross the fingers...

MPPT from Hong Kong to Pakistan in 8 Days.

I have ordered the following MPPT from a Chinese supplier through the website Aliexpress (http://www.aliexpress.com).

Ningbo Star Solar Co.,Ltd

China (Mainland) (Zhejiang)

45A Tracer 4215RN EP MPPT Solar Controller with MT-5 Remote Meter, FREE SHIPPING BY DHL

This MPPT cost me around 289 US dollar+ custom duty;).The ordering date was 01-June-2012 and as can be seen in the order tracking it just touched down Lahore today on 8th June, 2012. Wow pretty fast delivery...

Maximum PV input power this MPPT can work on is 24V /1170W. My current solar panels can generate 540W, However, I have ordered this MPPT because in future i want to double the quantity of solar panels with the same MPPT.

45A Tracer MPPT Solar Controller Specification:

Model No	Tracer-4215RN
Nominal System Voltage	12VDC | 24VDC Auto work
Rated Battery Current	45A
Maximum Battery Voltage	32V
Max. Solar Input Voltage	Tracer-4215RN 150VDC
Max. PV input power	12V/ 585W 24V /1170W
Self-consumption*	<10mA(24V)
Charge Circuit Voltage Drop	0.26V
Discharge Circuit Voltage Drop	0.15V
Communication	TTL232 / 8pin RJ45
Environmental parameters	Parameter
Working temperature	-35 to +55 C
Storage temperature	-35 to +80 C
Humidity	10%-90% NC
Enclosure	IP30
Mechanical	Parameter
Dimension	242 x 169 x 91 / mm
Mounting holes	180 x 160 / mm
Mounting hole size	5
Terminal	25mm /2
Weight	2.05kg

Home Sweet home for the sun tracker sensor!!!!

Finally, the sun tracker sensor is mounted in the weather proof glass jar.I have added jack-bolt system that can be approached outside the jar for precise adjustment and fine tuning of the sensor accuracy.

Here is a brief video of how does the adjustment work...

Winding up the wiring!!!

Here is my improved sun-tracker system mounted on Acrylic sheet and soon be enclosed in a panel box. It contains one 20x4 LCD for displaying different parameters of the sun-tracking system. I also added two Knobs for setting the sensitivity of the sensor and sampling time adjustment.

The East and West limit switches are the safety features of this sun-tracker. At 23:59 Hrs the solar panel is programmed to move toward East and stopped by the East limit switch. This will ensure that the solar panel start generating electricity as it receive the first ray of light and start tracking the sun till sunset.

Now my Sensor has four eyes

Here is the 4-LDR version of the sun-tracking sensor with on-spot adjustment using four potentiometers. The four LDRs improves the field of view of sensor.  The micro-controller programming has been changed and tested under wide conditions of lighting and its working great.

So why i used the potentiometers? Because the all the 14 LDR's in my hand provided me different readings in dark and extreme light conditions. Only two LDR's matched together and for the rest i was getting the calculated resistors values 2.5K and 2.8K which are not standard values resistors. So i came up with potentiometers where i can adjust them to get the precise resistance. Now all the LDR's can be matched with these variable resistances and the sensor will give me perfect results. I will lock the pots once adjusted.

Now by change in microcontroller programming i shifted the timing interval control from the firmware to the hardware. Now the user can select the sense/react timing of the sensor with a single potentiometer and can change the movement of panels from real time up-to 15minuts delay. Real time means the panel sensor continuously track the sun and command the motor to move. I will set this for 10minutes for myself i.e. After each 10minutes the tracking sensor will start to move the panel toward the sun.

Why MPPT Charge controller?

Maximum Power Point Tracking gives  10-30% more energy from the solar panels. These controllers are connected between the solar panel and batteries like any charge controller, but sophisticated electronics allow the controller to operate the solar panel at its most efficient voltage, resulting in significant gains in power.

When 50 Watts isn't 50 Watts

 As an example, consider a 50-Watt panel. The panel will typically be rated for full output power only at a particular voltage, say 17V, at which it will produce a little less than 3 amps.

When you connect this panel to your batteries with a conventional charger, the panel will operate at the battery voltage, say 12.6V. At this voltage, the panel won't generate significantly more current than at 17V, and the total output will be less than 40 Watts!

MPPT controller will let the solar panel run at its most efficient voltage, extract the most power possible, and charge the batteries at their voltage, with almost no loss. This way, a 50 Watts power can be received from the 50 Watt panel, a 25% gain over the conventional controller in the example above!

MPPT controller extracts the most power possible from the panel in nearly any condition: hot or cold temperatures, different light levels, partially shaded panels; it even takes wiring losses into account. The actual power gain will vary with conditions, and may be anywhere from 0-40%, with 10-30% being typical. Highest power gains come with discharged batteries, cold temperatures, and lots of light. 

More accurate and Sensitive Suntracking Sensor

I have replaced the 10K resistors with more precise 3.2K resistors at the output of the LDR's  to analoge pins of microcontroller. These resistors are calculated for the available LDR's.

Following Formula was used:

LDR resistance(Ohms) = SQRT ( Rdark x Rnoon)

Where Rdark = Resistance of the LDR in night (No light condition) =247 Ohm

          Rnoon= Resistance of LDR at high noon (direct under the sunlight) =39000Ohm

LDR resistance = SQRT (247 x 39000)

                       = 3101 Ohm = 3.1 ohm

                       =3.2 is the nearest available resistance

Here is the spreadsheet version:

and a short video after 10K resistance replacement with 3.2K.

My Sun-tracker is Alive

Here is a short video of sun-tracker in working condition. It took my sunday to find out the weired behavior of sun-tracker. I found out two 10K resistors were the culprit on the PCB. I just removed them from the PCB and installed them directly on the sensor Analogue input wiring. My next goal is to make a pretty weather proof enclosure for the sun-tracker and electronics panel box.

My old video of sun-tracker testing:.

The latest video of my sun-tracker.

Calculating Energy efficient Tilt Angle for Solar Panel

As I have already discussed in the previous post that i am adding single axis tracking to my solar panel and the Altitude angle (Tilt angle) shall be adjusted in Summer and Winter to get the maximum efficiency out of the solar panels. Here are the Rule of thumb for best tilt angle.


 SEASON------------------- ANGLE TILT CALCULATION

Winter    --------------------  (Latitude x 0.89) + 24 degrees
Summer  -------------------  (Latitude x  1.05) - 24.3 degrees
Spring & falls --------------   (Latitude x0.98) - 2.3 degrees

Pakistan resides in Northern hemisphere so the Solar panel should be toward the TRUE NORTH. The Tilt angle is calculated from the Horizon.

Example:

City :  SADIQABAD, PAKISTAN
Latitude (from google) : 28.1700 N  
Tilt Angle for Winter= (28.17 x 0.89) +24 degree  = 49.07 
                               = Say 49 degree  from horizon or   (90- 49 = 41 degree) from the vertical
Tilt Angle for Summer= (28.17 x 1.05) -24.3 degree  = 5.27 
                                = Say 5 degree from horizon or (90-5 = 85 degree) from the vertical
Tilt Angle for Spring & Fall=  (28.17 x 0.98)-2.3 = 25.306
                                 =  Say 25 degree   from horizon or (90- 25 = 65 degree) from the vertical


As these solar panels i intend to install in Karachi so:

City :  KARACHI, PAKISTAN
Latitude (from google) : 24.8508 N  
Tilt Angle for Winter= (24.8508 x 0.89) +24 degree  = 46.11  = Say 46 degree  (90-46 = 44 degree )
Tilt Angle for Summer= (24.8508 x 1.05) -24.3 degree  = 1.79  = Say 1.8 degree (90-1.8=88.2 degree)
Tilt Angle for Spring & Fall=  (24.8508 x 0.98)-2.3 =  Say 23 degree

Testing the Solar Tracking module

Here is a brief video of solar tracking module.

Updates on Control module and Panel Support Structure

Micro-controller modules are completed .

Solar panel structure with single-axis sun tracker installed. I have used one Car windshield motor (Rs.700), motorcycle chain sprockets set (Rs. 450)  and a second-hand car wheel hub (Rs. 1600) to make a single axis tracking hardware.

 The structure material ,assembling and painting cost was around Rs.8000.

 I have also purchased 60V 10amp MPPT charge controller (Rs.8750), However, i am seeking to purchase 60Amp 160V MPPT charge controller (TS-MPPT-60 ) through credit card from America as its not available in Pakistan.http://www.morningstarcorp.com/en/tristar%20mppt It will cost me around 550 US dollars including taxes/duties.

purchased 02 Lead Acid batteries FB make 220AH. Cost me around Rs.24000. I preferred FB because the maintenance free deep cycle batteries are quite expensive and the market is full of poor quality Chinese batteries. Later on i shall discuss on this.

Why Single Axis Sun Tracking?

After successful completion of the DC Motor controller , it is time to make the Heart of the control circuit. I have recently completed the AVR based Single Axis microcontroller circuit for Azimuth tracking of the sun.

Using dual axis solar tracking is a good idea but controlling the Altitude motor with respect to sun has very little benefit as compare to Azimuth control.Let us see the following figures for explanation:

The position of the Sun in the sky relative to an observer on Earth is defined by its altitude angle α (solar elevation angle) and its azimuth angle Ψ. The sun moving from East to West and the this angle we call it Azimuth Angle. The sun daily cover this Azimuth Angle. However, The Altitude Angle of the sun is changes throughout the year with a very very little increments during the year days.In winter the sun is more toward the Southern side and Altitude angle is small . Whereas in the summer the Altitude angle is on the extreme and sun is just traveling at the top of our head;)..

 This is the reason I prefer to use Azimuth control of my solar panels.

Here is the micro-controller(ATMEGA328P) based single axis Azimuth control circuit with East-West limit switches. In future i shall explain how will this work.

Low Cost DIY DC Motor Controller for AZIMUTH Control

Recently i designed a low cost DC motor controller using relay, MOSFET IRL540N. This circuit can handle up to 5A current and i shall use this for AZIMUTH control of my Solar Panels. I shall use wind power shield motor to run on this circuit.

This circuit is under testing with micro-controller and doing fine so far.

Revised Sun Tracker Sensor

In the last version of sun tracker sensor, The cross was erroneously mounted with 45 degree offset with LEDs. Also the diameter of the cross was almost equal to the diameter of LEDs, which is not correct as the shadow of the cross will not cover the complete LED.For highest resolution, i can keep both the Cross and the pipe at the same height as i have done in my old version of sensor, but in this case the motors won't halt at any time and oscillate between forward and backward.
So to avoid frequent forward and backward motion and to conserve electricity to drive the motors i set a rule of thumbs "The Height of the cross should be 30% more than the height of the pipe" and "The diameter of the cross should be more than twice the diameter of LED".
This will be cater for in this revised version.

Updates on Sun Tracker Sensor

Here is the updates on the Sun Tracker sensor.. The sensor testing is still in Progress...After testing of this sensor, A better revised circuit version will come out later..

My first mistake, The cross is offset by 45 degree.. It should be aligned with the Sensor LED's..