It all started about a year ago at work when my boss went to throw out a perfectly good plastic battery box from his car. I took it home and it sat in the garage for a while until one day my two daughters started fighting over an iPod charger. Such a modern day dilemma! One day while browsing on Instructables, I came upon an interesting guide by Lewis02 about his "Solar Power Supply" and it gave me plenty of inspiration to find a solution to the bickering.
After some searching, i found a 42Ah AGM battery which was old and never used but in good working order. I mounted it into the free battery box and coupled it to an 80W mono solar panel with a budget $20 solar controller. I fitted out the box with some fuses, a couple of 12v outlets and those cheap 12v to USB car socket convertors and that was the end of the ipod argument!
Now almost twelve months later, the solar bug had well and truly bitten! The original unit had reached its capacity and now it was time to upgrade...
Step 1: Start Small But Think Big
I decided to add some more batteries to cater for our families growing use of modern technology. Now the one battery setup increased to four in total and now after using this system for about four months and being more energy conscious there has been a decline in our electricity bill so far by approximately 15%.
I looked at building a storage box for extra batteries but after coming across a secondhand TV cabinet for $20, it became the base for my project. It had plenty of storage and strength to cope with the added weight and didn't look too odd in the living room of our home.
The unit, although quite heavy, has wheels underneath and having Anderson type connectors allow disconnection from the panels to make it mobile.
Step 2: Some Fabrication Is Necessary
I work with cars and metal so woodworking is not my thing. The beauty of repurposing/upcycling this unit meant I stopped it from becoming firewood while not having to struggle to build something from scratch!
The hardest modification was cutting up the two panel inserts to fit the shelf where the VCR/DVD player would usually fit in. There is one black panel in front set back just past halfway. This houses four 12v cigar sockets, a pair of power switches and two voltmeters. It also creates a cavity for the wiring to be hidden in behind all of which is accessible by another panel mounted on the back.
The blue voltmeter seen here is the current battery voltage and is positioned up high so when you watch TV at night, it isn't in view. The yellow voltmeter is wired to the panels and when the solar output falls below 7 volts, it switches off so it's not distracting by night .
Step 3: Filling Up the Storage Area
I have been slowly adding batteries to the point where there is no room left. I went from one 42AH AGM battery to four in total! They produce plenty of power for this setup and with about 3-4 days of cloudy weather, typical loads will bring them down to about 50% capacity.
As this system is always inside, I wanted AGM type batteries as they are less of a safety hazard than standard car batteries. I also installed four vents in the back for air circulation as well as adding an illuminated computer case fan.
I was using the inverter (which is sitting atop of the subwoofer) to power the audio system until I came across some desktop computer speakers that could be directly powered from the batteries.
I also have some 12V LED downlights which take power from the system too.
Step 4: Solar Panels Are Necessary
I started with one 80W mono solar panel which wasn't much of an issue on the balcony but with an extra few more, my wife has had enough! I've purchased some mounting rails and brackets for the roof so thats my next project.
These panels are all 80w and rated at 4.4 Amps max each but the controller has current limiting to 15 Amps to prevent overloading. They output about 5 Amps an hour on a cloudy day. The picture was taken in the middle of the day and, apart from the shading from the poles and railings, they still can get a reasonable amount of sun. The three panels produced just over 60Ah on one sunny winters day.
Step 5: The Solar Controller
The most important part of the system has to be the Solar Controller. I originally had a Chinese ebay 15Amp Controller in my original battery box project. It charged the battery okay but wasn't very efficient. The Morningstar Sunsaver 15Amp I use now outperforms the Chinese unit for efficiency and performance so I think it is well worth the money. The best feature I found is its data-logging capability (See step 10). This is excellent for knowing exactly how the system is running and whether an upgrade may be necessary.
More info from their website http://www.morningstarcorp.com/en/sunsavermppt
Step 6: 12V Picture and Sound
Its been hard to convert the family from using a 50" Plasma TV for hours on end, to a 24" LED Screen running on 12V. They seem to have gotten use to the change and this has been the biggest saving in grid power usage so far. It's always funny to see the looks on the faces of our visitors when I explain that the Plasma is only for special occasions!
As with most budget TV's, the inbuilt sound is dismal so the next addition was a desktop computer speaker system. They are perfect as they are compact, have an input voltage of 13V DC, draw less than 1 Amp and are surprisingly powerful.
The speakers are held up in place by some strong double-sided tape and the subwoofer is hidden in with the batteries.
Step 7: Interface Devices
Having a home with WiFi has many advantages especially when it comes to streaming media.
I added my Raspberry Pi http://www.raspberrypi.org inside the battery compartment close to the fan for cooling and it is fed 5V power through a Kensington Car Adaptor. It has a WiFi adapter and has Openelec software running Xbox media centre.
I found our WDTV media box will run on 12V directly and while it too streams media from the home network like the raspberry pi setup, it's ability to play many different video formats comes in very handy for watching backup movies straight off a portable hard drive. No more scratched discs!
Step 8: Audio and Video Control Unit
This little unit diverts the picture and audio from the all the devices to the TV and speakers. It has all the connections coming in at the back so they are hidden from view. There are quite a few cables required to get everything working but once sorted, it's so easy to use. The best feature is that no power is required for it to work.
Step 9: Charge, Charge and More Charge
Most people these days have smart phones which seem to require constant charging. Its funny to see everyone sitting on the floor like campers around a fire!
Plenty of charge options are available from four power outlets, eight USB outputs, two laptop chargers and a charger for the portable DVD player (which is handy for watching movies in bed).
Behind the entertainment unit is a 12V car jumpstarter pack which has a capacity of 22Ah and is constantly trickle charged. Being portable, it gets a lot of use outside. I have a 2300 litre rainwater tank that I draw from with a 12V marine washdown pump and this pack allows me to wash out the pool filter and up to three cars before it gets down to 50% depth of discharge.
Next was the radio. I thought about installing a car stereo but that would take up too much room and add to the huge amount of wiring already done so I opted for a small MP3 player with radio functionality. It runs all day and has 5V USB charging which makes it perfect for this setup. Other music is available via the iPod, CD's in the portable DVD player or through online streaming.
This unit provides a great source of 12V power and its surprising to find how many appliances quite happily run on it but the biggest consumers so far have been from laptop chargers which will draw upwards of 5 Amps due to the voltage having to be stepped up to about 19V.
I also have a lamp powered by this setup https://www.instructables.com/id/Solar-Powered-Floor-Lamp/
Step 10: Morningstar PC Software
The Morningstar controller has PC software which is accessed via a meterbus adaptor. This allows for programming parameters and downloading data. I find myself using this software constantly. It is an invaluable tool to determine how well the system is working. There are so many variables as seen in these screenshots and there is also a datalogging function to record selected variables!
Step 11: Conclusion.
I never set out to make this a super low budget setup. I believe it is a good compromise between cost and entertainment value. All up I've invested about $1500 which is about the cost of the Plasma TV! I see this as a good investment though, as I have learned a great deal and has created an interesting hobby.
There is always room for improvement and additions and I've considered 12V outlets in other areas of our home but at this stage it's better to be a standalone unit so its isolated from the rest of the house. It also has the bonus affect of making our family more social having to be in the same room together!