How to Build Your Own Portable Solar Kit

Tuesday, December 12, 2016
Zubin Shrestha
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Solar technology has emerged as a reliable source of energy in the Nepalese energy market. Being the cleanest and most profuse renewable energy source available, it is practically free and emits absolutely no harmful by products. At WPN, we imagined a solar system that you could take with you on the go. Whether it be a weekend camping trip or a rigorous expedition to Everest, we wanted to build a system that could withstand anything it was dealt with, whilst being highly portable, durable and effective. This project was a prototype experiment and can even be used as a small off grid power source for numerous demanding appliances.

Motivation

We had received a quotation inquiry from a climbing expedition group for a portable solar system that was to be capable of the following:
  • Trickle charge battery of reasonable capacity
  • Have lighting connections
  • Charge laptops and radios
  • Provide USB, 12V and standard AC
The panels were needed to be easily carried and a waterproof casing was required to house the electronics.
From the initial inquiry, the engineering team drafted various ideas on how to build a suitable system capable of fulfilling the energy needs of the different appliances. This involved using various combinations of solar modules and batteries. As the system needed to be as portable as possible, weight and mobility were crucial factors that had to be taken into account for the system design. The Nepalese market was very limited when it came to lightweight solar modules and batteries so the system also had to be designed accordingly to the availability of locally available resources.

Materials

  • 4 X 20W Solar Panels
  • 42Ah 12V AGM Sealed Battery
  • 8A Charge Controller
  • Power Converter
  • Solar Wiring
  • DC Connectors (Male & Female)
  • Glue Gun
  • Wire Terminals
  • Crocodile Clips & Clamps
  • Plastic Container
  • Cable Ties
  • Soldering Iron, solder and flux
  • Wire Stripper
  • Screwdriver
  • 40A fuses
  • Power Strip
  • Multimeter
All the aforementioned materials were purchased from the local market.

Imagining the System

It was agreed that the system would comprise of external solar modules and battery separate to the electronics. A container or as we called it, ‘The Box’ was required to house all the electronic components of the system (i.e. charge controller, power converter, power strip, and wiring). As the system was to be used in harsh terrain and conditions, the Box needed to be robust and protective. An early draft design is shown in the rough schematic diagram below.

initial-scehmatic

For an 80W solar panel module, taking mobility and the client’s energy demands into account, we decided the optimal battery size to be 42Ah. Various combinations of different solar panel capacities were discussed and finally it was decided that four 20W 36-cell Monocrystalline Solar Panels were to be linked in series. One master panel would be constantly linked to a container that consisted of four female DC connectors for easy plug-and-play use. Three of these connections were meant for the other three solar panels and one was to connect the solar panels (which were in series) to the charge controller and power converter in the Box.

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The makeshift connection container was built using a plastic lunchbox and linked the solar panels to the other electronic devices in the system. The image below shows this connection container and the DC connectors it enclosed. All the wiring for the connectors were soldered to their respective terminals.

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Every connection within the system was linked by DC connectors which made the entire system plug-and-play and completely fool proof.

System Assembly

Before initiating the assembly stage of the project, the system components were all tested to provide more control and flexibility if any changes were to be made during assembly. Once it was noted that the system was running smoothly, it was time to put all the modules together. The testing phase of the project is shown in the following image. A laptop and two smartphones were obtaining charge from the system with ease.

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A Pelican case was used to house the electronics which provided ample protection from weathering and harsh conditions as the system had to be transported on the back of a YAK! The glue gun was used to seal all the wiring connections in the connection container for waterproofing. The final assembled system can be seen in the following images.
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Wind Power Nepal are currently working on an upgraded higher capacity, lighter and much more mobile system.
7CONTACT US IF YOU ARE INTERESTED BUT TOO LAZY TO BUILD YOUR OWN 😉

 

(Disclaimer: The views and opinions expressed in this article are those of the authors and do not necessarily reflect the official policy or position of WindPower Nepal Pvt Ltd.)

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