Quest to build a portable Solar powered generator (Part I)
December 26th, 2008
I recently decided to embark on a project to create a Solar Powered Generator. It had been a while since I have had to apply my training I gained from the electronics principles courses I took while I was in The United States Air Force, but much to my surprise I remembered a lot of my training having not used it in a while. There was an extensive amount of research and the most daunting tasks weren’t actually designing the Solar Power Generator, but finding places that had a good selection of low cost, but still good quality parts for building this project. I found that the best one stop shop for finding all the parts needed for the project was Amazon.com. After numerous Google Searches and countless hours online researching and asking questions, I finally came up with a solid product that was low cost, but efficient and safe. The goal of this project is to create a completely renewable energy server farm. The server farm utilizes a small community of Apple Mac Minis which consume roughly 45 watts to operate. The reason the 500 watt output number is needed, is because the output of the solar panel generator will interface with an UPS before the power reaches the Mac Minis. A design flaw in this is the loss of energy from the solar power collected, to the Mac Minis themselves. The output is never equal to the input.
The first part of my project entailed laying out the technical specifications of what I wanted. Below were the requirements of what I wanted.
· Safe for in-home use
· Capability to provide at least 500W of power
· Under $1000 in parts
· Simple design that anyone can replicate
· Portable, with the ability to disassemble and reassemble with ease
· Will last a minimum of 3 years with no replacing of parts
Given those specs a few questions arose that I needed to get answered prior to the design and implementation phases of my project. A few of those questions I came up with during my brainstorming the design phase are listed below.
1. How many batteries will I need to support the 500 Watt output feature?
2. How many Solar panels will I need to support the 500 Watt Output requirements?
3. What are some safety considerations to look into?
4. Why are Marine Batteries recommended?
5. Do I need to use “sealed” batteries?
6. How do I choose the correct voltage regulator for my project?
7. Should I wire the batteries in parallel or series?
8. How many solar panels will my project require?
Battery concerns.
There are several different options for batteries. For a low cost solution, used fork lift batteries from a military surplus store will suffice. If your generator is intended to be used in the home, it is recommended a “sealed battery” be used which can be achieved using a “sealed marine battery”. Other battery concerns are the length of life and quality of power production. The power production issues can be addressed by using a “deep cycle battery”. The batteries are the second most important part of the generator. Batteries dictate how often you must replace parts and how much power you can generate. If you wish to keep your generator outside, consider purchasing a battery box to help prevent the outdoors from ruining your battery.
Solar Panel Considerations.
Solar panels are probably the most important aspect of your design. Quality, price and durability are the three most important factors of concern when trying to determine which solar panel(s) you should buy. There are many vendors that supply Solar Technology and manufacture Solar Panels. A few of the Solar Panel manufacturing companies are Sharp, BP Solar, etc.
Key Components.
Solar Panel
Voltage Regulator
The voltage regulator chosen was a 7 Amp Charge controller made by a company called, “Sun Force”. You can buy the bundled Sun Force 60 Watt Solar panel with the 7 Amp Charge controller as well for under $500. If that price is a bit steep, for under $150 you can purchase the bundled 15 Watt Sun Force Solar Panel with the charge controller. The latter option has limitations on the power you will produce, but if is best to start off with a low scale solution until you have perfected you design. The great thing about solar powered generation systems is that they are very easy to scale and build onto. As power requirements are demanded, it is fairly simple to reconfigure your solar powered generation solution.
Resources.
Some great sites are available on the internet to refer to for the planning of your solar powered design. One such site, Solar Home, offers guides and tips as well as parts to build you Solar Project.
A few good books that are available to help assist in designing, understanding, and implementing a successful Solar Powered Generator Project are listed below.

Solar Power Your Home for Dummies.
