DIY Solar Powerwall

This is just an instructable about making a Solar Powerwall to be able to charge devices completely from a solar panel. I wanted to make this due to the immediate need for more renewable energy and because I did not want to pay the absurd amounts of money for a commercial Powerwall. The following system charges 3 SLA(Sealed Lead Acid) batteries in parallel via a solar panel and solar charge controller. It then is connected to an inverter for which I charge my laptop from it. These batteries are each 35Ah, in parallel making this an approximately and theoretical 100Ah system. Being fully charged, this could recharge my phone from being completely dead 33 times (3hr charge time at 1A) before needing to be recharged!

• Cabinet (or make your own)
• High capacity batteries
• Solar Panel
• Inverter(optional)

This step may not be necessary for some people if you already have a sufficient enclosure or have different batteries, but I reused an old cabinet which could not handle all the weight. I bought some brackets from my local hardware store as well as some aluminum angle stock. I used the brackets to reinforce the shelves and I used the angle to create slots for the batteries to slide into to make sure they stay in place. I also added casters to the bottom of this to help with mobility, as it is very heavy full. I also added a cabinet lock or catch thing to keep the door from swinging out, but I did not have the piece that it latches around so I ended up 3D printing the piece which can be found here on my Thingiverse page.

Prior to wiring your batteries make sure to do research on how to connect them if you are not confident enough as connecting them wrong could be very disastrous (especially at this high capacity). This will be relevant to my case using high capacity SLA batteries in parallel. I firstly ensured that each battery was the same nominal voltage (12V) and same type of battery. To connect these in parallel you must ensure that they are all at the exact same voltage, otherwise they will attempt charge the lower battery and it will cause imbalance. I did this by measuring each battery and selecting one value to focus on. I had one battery that was too low (about .2V) for which I connected it to a commercial charger and watched it closely until it got to the same voltage. The other battery was too high, for which I used a large 100W potentiometer to drain the battery at whatever set current I wanted and watched the voltage drop until it again reached the same voltage.

Once the batteries are connected you can connect them to the solar charge controller and the solar panel to it after (make sure to follow the controller directions). After that you can connect the battery to the inverter should you use one. Make sure to wire in some fuses between the batteries and the charge controller and inverter, to ensure that something doesn't accidently blow up!

This is my finished product, which may take a long time to charge the batteries, but it still works very well and I am glad I can charge my devices from completely clean and free energy! Hope you enjoy!