In this tutorial, I walk you through everything you need to know to make your own DIY solar power pack.
This is a perfect tool for any outdoor use such as camping, hiking, hunting, offroading, fishing and survival situations. During the storm / grid power cut off, you can use it at your home also.
I made the Solar Power Pack by considering the following factors :
1. Should be portable
2. Should be affordable
3. Can deliver AC /DC power during emergencies
4. Should look descent.
I used a one of my refurbished Quad Copter carrying case for making the enclosure. Here is what I came up with – the finished product.
The features of my Solar Power Pack are :
Charging : Solar as well as AC mains
Solar Panel Rating : 10W
Output Voltage (V): 2 x DC12V , 2 x USB 5V 1 A and a USB 5V , 2.1A
Battery: 12V/12AH Sealed Lead-acid
Solar Charge Controller : 3A, PWM
Inverter Output : 200W / 220V
LED Light : 12V/3W
Weight: 6.3 Kg
Size: 340x230x3 mm
Full Project is also available on Instructables
Step 1: Parts and Tools Required
1. Solar Panel ( Aliexpress )
2. Battery ( Amazon )
3. Solar Charge Controller ( Banggood )
4. Inverter ( Banggood )
5. Dual USB Socket ( Banggood )
6. DC Jack ( Amazon )
7. Switch ( Banggood )
8. 12V Toggle Switch ( Gear Best)
9. Volt Meter ( Banggood )
10.LED Holder ( Banggood )
11. Female Power Jack ( Gear Best )
12.Resistors : 1K
13. Heat Shrink ( Banggood )
14. Crimping Terminals ( Banggood )
15. Carrying Box ( Banggood )
16 . Battery Charger ( Amazon )
17. Screw terminals row ( eBay )
18. USB LED Bulb ( Banggood )
19. Self adhesive Velcro ( Amazon )
1. Drill ( Gear Best )
2. JigSaw ( Amazon )
3. Soldering Iron ( Gear Best )
4. Hot Air Blower (Gear Best)
5. Hot Glue Gun ( Gear Best)
6. Wire Stripper ( Gear Best )
Step 2: Which Type of Battery Is Best for Solar ?
The choice of right batteries possibly the biggest decision to be made if planning a solar power system of any size.
You have multiple options but choosing the right battery is very important.
Types of Battery for Solar Applications :
1. Lead Acid
2. Li Ion
3. Ni Cd
Out of the above 3 types of batteries lead acid batteries are used in most of the renewable energy storage due to their low cost.
1. Lead Acid Battery :
The simplest way to store energy from a solar panel is by using of your car battery.But this isn’t a good fit for Solar application.They are made to deliver short bursts of power and stay at full charge most of the time, making them unsuited for solar applications.
The best option for solar application is Valve-regulated lead-acid (VRLA) batteries include absorbed glass mat (AGM) and gel models.These batteries have increased performance and total energy output making them a good choice for Solar applications.
2. Li Ion Battery:
Lithium-ion batteries can typically deliver more cycles in their lifetime than lead-acid. This makes them a good choice for portable solar power applications .The most important benefit lithium-ion provides for solar is its high charge and discharge efficiencies, which helps to harvest more energy. Lithium-ion batteries also lose less capacity when idle, which is useful in solar applications.
Li-ion batteries typically come in one of three formats: pouch, cylindrical, and prismatic (rectangular-cubic).The best candidate is the prismatic lithium iron phosphate (LiFePO4; LFP) battery.
3. Ni Cd Battery :
I do not have much idea on NiCd battery.I will update this part later.
i. Cost : Li Ion is costlier than lead acid (AGM ) battery.
ii. Weight : Li Ion is lighter than the lead acid (AGM ) battery of same capacity. Li Iron Phosphate is about one-third the weight of a lead-acid battery.
iii. Space : Li Ion battery take about half the volume of lead acid battery of same capacity.
iv. Life and performance : LiFePO4 battery has the longest cycle life and better high temperature performance
I have described all the pros and cons regarding the battery. Now you can choose according to your priority.
For making Portable Solar Power Pack the best option is Li Ion battery.But keep in mind, you need a balance charger to charge it.
If you are tight in budget and happy to carry some extra weight then buy a good quality AGM battery.
It is cheaper and reliable.
Li ion battery image source : Power Brick
Step 3: Solar Panel Selection
In general Solar Panels are of 3 types i ) Mono Crystalline ii) Poly Crystalline iii) Thin film
Efficiency : Mono crystalline is most efficient and thin film is least efficient panel.
Cost : Mono crystalline is the most expensive and thin film is cheapest panel.
Area Occupied /Watt : Mono crystalline panel require lowest space than the other two.
High Temp Performance : Thin film has best performance under higher temperature than mono and poly crystalline panel.
Poly crystalline have all the the above performance in between the Mono Crystalline and Thin Film. So they are widely used.
For a portable Solar Power Pack you have to consider two important factors 1. Space 2. Weight
From the above comparison its clear that Mono crystalline is the best option for this application.Again these panels come with aluminium frame or epoxy coated. By taking the weight in to consideration, I will suggest to use epoxy coated mono crystalline panel.
My enclosure top area was 42.5* 33.5 cm . So maximum 10W panel can be fitted on it. I have used a mono crystalline panel which is only 294 grams, where as the poly crystalline with aluminum frame of same rating is 929 grams. No doubt the price of the mono panel is 2.5 times than the poly panel.
Specifications for the Solar Panel :
Peak Power: 10W
Cell Efficiency:> 19.2%
Open circuit voltage: 22.4 V
Operation Voltage: 18V
Short Circuit current: 0.62A
Current at maximum power: 0.55A
Maximum system voltage 1000 V DC
Size: 340x230x3 mm
Sizing : For more details go through my Instructables on " DIY Off Grid Solar System "
Step 4: Solar Charge Controller
A solar charge controller is a device which is placed between a solar panel and a battery. It regulates the voltage and current coming from your solar panels .It is used to maintain the proper charging voltage on the batteries. As the input voltage from the solar panel rises, the charge controller regulates the charge to the batteries preventing any over charging.
There are two types of Controlller 1. PWM 2. MPPT
MPPT are costlier and heavier due to the bulky inductor coil inside of it. So I will suggest to buy a PWM charge Controller for a small system.But if your system is bigger, then you can go for MPPT.
Presently I am using a SLA battery but in future I will replace it with a Li Ion battery. So I choose a PWM charge controller, which can charge multiple chemistry batteries, so that in future I don't have to change it.
Specifications of the Controller :
1. Compatibility with a variety of storage batteries such as VRLA battery, gelled electrolyte (GEL) Battery, 3.2V x 2 iron-phosphate-based lithium batteries 3.2V x 4 iron-phosphate-based lithium batteries, 3.7V x 1 iron-phosphate-based lithium battery.
2. Maximum solar panel Spec 18V / 40W
3. Maximum open circuit voltage 23V
Note :This charger is not tested with Li Ion Battery.I am not finding a good quality Solar charge controller for multi cell li ion battery pack.
If I get, will update here.
Step 5: Inverter
Solar panel (PV) that receive the sun’s rays and convert them into electricity called direct current (DC). DC is then converted into alternating current (AC) through a device called an Inverter.
1. Square Wave
2. Modified Sine Wave
3. Pure Sine Wave
Pure Sine Wave Inverter are costlier among the all but they are very good for the appliances.
I used a modified sine wave Inverter , because its just for emergency use not for continuous run.
Inverter Specification :
Input Voltage: DC12V(11-14V) 25A
Max Output Voltage: 220V ±5%
Rated Output Power: 200W
Output Frequency: 50HZ±4HZ
Conversion Efficiency: ≥ 87%
USB Output Voltage: 5V 1A MAX
Step 6: Make the Stencil
Grab your note pad and vernier caliper, note down the measurements.
Draw the same sized shapes on the paper or you may place the components and mark around it. Cut out the stencils.
Step 7: Make Slots for Components
Place the stencils on the enclosure and fix it at the edges by using duct tape.
For small circular hole, use suitable size drill bits.
For bigger hole ( circular and rectangular ) , first drill few holes and then use jig saw to make the exact cut out.
After making the slots, remove the stencils.
To fit the components perfectly, you may need little filing.
Step 8: Intsall the Inverter
The ON/OFF switch is on the back side of the Inverter. To access it, I need to open the enclosure each time.
So I made an arrangement for external switch.
First unscrew the Inverter back plate and cut the wires connecting to the switch.
Then connect a external switch with longer wires.Close the back plate.
For mounting the Inverter, first glue a thick foam board.
Glue the Inverter just above it.The output sockets should be out side.
Then installed the external ON/OFF switch.
Apply hot glue to fix them in to the slots.
Note : The inverter cooling fan is inside the box,so keep the box open during Inverter in service. Otherwise you have to make a separate arrangement for cooling.
Step 9: Making the Terminals
For easy wiring of the components,I connect terminals wire first.
Solder 14AWG copper wire ( approximately one feet ) to terminals of LED Light and 5mm jacks.
The dual USB socket come with crimping terminals.Crimp the terminals by a suitable crimping tool.
Insulate the joint by applying proper heat shrink.
Step 10: Install the Components
Few components comes with nut and washers , you have to just tight it properly.
For installation of other components, use hot glue.
If the components not fit properly to the slots, file near the edges.
Step 11: Wiring Diagram
The Wiring diagram is pretty simple. It consist of Charge Controller, Battery ,Inputs , outputs , junctions , switches and fuse.
Charge Controller : This is a PWM type charge controller. It has 3 terminals : Solar , Battery and Load.
Wire from the Solar and battery is connected to the respective terminals, load terminal is left unused due to its small current rating.
Battery : 12V and 12AH sealed lead acid battery.
1. Solar : This is a DC Female Power Jack with Screw terminal. The out put terminal ( Male Jack ) from the solar panel is connected it.
2. Charger : This port is for charging the battery from AC mains by using a Battery Charger.
1. Inverter : Convert 12V DC to 220V AC.Suitable for laptop,fans,LCD and small house hold appliances.
2. LED : A 3W LED for lighting. You can use it as a powerful flash light.
3. USB : 2 USB ( 2.1A and 1A ) ports for charging Smartphones ,tablet and running any USB device.
4. 12V DC : 2 5mm jacks for 12V DC output.Suitable for music player or decoration light.
Just connect the terminal wire from the above to the respective ports in the Junction.
5. Volt Meter : The Volt meter I used have 3 wires ( Yellow, Red and Black ).The red and black wire is for power and yellow is signal wire. As the power source and the voltage to be measured is the same battery.Short the red and yellow wire together.
6. LED1 : This is green LED for indicating solar charging.The 1K resistor connected with series is to limit the current.
7. LED2 : This is RED LED for indicating low battery condition.
Junction : As all the out puts are taken from the Battery, you need to join the terminal wires to it. So to make a neat connection, I used screw terminal row for making the junctions.
Switches : Switch S1 is the main switch for all the loads.S2 is volt meter switch , S3 is Inverter switch , S4 is combined switch for USB and 12V output and S5 is LED flash light switch.
F1 : This a fuse holder.Use a suitable fuse according to your load.
Step 12: Wiring
Connect a diode in series with the positive terminal of solar panel. It is to block reverse current flow ( Battery to Panel ) during night.Then join the red wire to the diode negative terminal and black wire to the Solar panel negative terminal.
To make the junction with same voltage ( common potential ), join small strips of wire alternatively.See the pics.
Then connect all the wires to the respective ports as per wiring diagram.
Solder 1K resistor to the long leg of green LED, then solder the terminal wires. I used a LED holder for nice fitting in to my enclosure.
After all the connections, insulate the conductive parts by using suitable heat shrink tubing.
Step 13: Mount the Solar Panel
You can mount the solar panel in two way, either by permanent fix or detachable.I prefer the second option. If the Solar panel is fixed permanently to the enclosure, then you have to put the entire system on sun light to charge the battery.But inside the enclosure box, electronics items are there which are not friendly to the high temperature. To prevent from rain water and sunlight, the alternative option is making a long extension wire with detachable Solar panel.
I used self adhesive Velcro to mount the Solar Panel, the bonding is really nice. You can easily detach the panel also.
To insert the solar panel extension wire , make small hole on the enclosure.
Step 14: Mount the Battery
First glue a thick foam board as shown in the image.
Apply hot glue to the battery surface and paste it to the enclosure surface.
Note : This is not a proper way to mount the heavy lead acid battery.I made it just for temporary arrangement.Later I will fix it by using an aluminum channel and long screw.
Step 15: Arrange the Wires
After completions of wiring, the wire are really messy.Arranging wire properly is important because, if any fault occurs in the system, you can easily identify it.
I arranged the wires by making groups and stick to the base by using duct tape.
To mount the solar panel extension wire, I used self adhesive Velcro to make a holder.See the above picture.
After dressing the wires, the final look is really neat and clean.
Step 16: Testing
Before testing, thoroughly check the wiring.Anything wrong can damage the components.
If the wiring is perfect, connect the battery terminals and then turn on the main switch (S1).
Switch on the voltmeter. if the battery voltage is perfect ( greater than 12V ), turn on the LED switch , it should be lit up.Switched on the Inverter Switch , the led in it should be lit up and you will notice the fan sound.
Switched ON the USB switch, the back lit led should glow.
Now the system is ready for use.Connect your smart phone / tablets to USB and laptop charger or camera charger to the Inverter socket. It should work.
To charge the battery from mains AC, plugin the charger to the charger socket.
Step 17: Finishing
The final product come out is really nice.I really love it.The only problem is heavy lead acid battery, which is over weight for a quad copter carrying case.
Hope you enjoyed reading about my project as much as I have enjoyed building it. If you’re thinking about making your own I would encourage you to do so, you will learn a lot.
If you have any suggestions for improvements, please comment it below .