Off-grid living isn’t for everyone, but it has gotten easier in recent years. Cheap solar panels and wind turbines let you generate your own power, and there are plenty of strategies to deal with fuel, water and sanitation. But the one thing many folks find hard to do without – high-speed internet access – has few options for the really remote homestead. [tlankford01] wants to fix that and is working on an open-source mesh network to provide high-speed internet access to off-grid communities.
But first he had to deal with a major problem. With high-speed access provided by a Clearwire wireless network, streaming content to his two flat-screen TVs wasn’t a problem. At least until Sprint bought Clearwire and shut down the service in early November. Another ISP covered his area, but his house lies in a depression out of line of sight of their tower. So he rigged up a bridge between the WiMAX network and his lab. The bridge sits on a hill in sight of the ISP’s tower 3.5 miles away. Solar panels, a charge controller and deep-cycle batteries power everything, and a wireless link down the hill rounds out the build.
This is obviously a temporary solution, and probably wouldn’t last long in winter weather. But it’s working for now, and more importantly it’s acting as proof of concept for a larger mesh system [tlankford01] has in mind. There are plenty of details on what that would look like on his project page (linked above), and it’s worth a look too if you’re interested in off-grid connectivity.
Imagine you’re building a small solar installation. The naive solution would be grabbing a solar panel from Horror Freight, getting a car battery and AC inverter, and hoping everything works. This is the dumb solution. To get the most out of a solar you need to match the voltage of the solar cell to the voltage of the battery. How do you do that? With [Debasish]’s entry for The Hackaday Prize, an Arduino MPPT Solar Charge Controller.
This Maximum Power Point Tracker uses a buck converter to step down the voltage from the solar cell to the voltage of the battery. It’s extremely efficient and every proper solar installation will need a charge controller that does something similar.
For his MPPT, [Debasish] is using an Arduino Nano for all the math, a DC to DC buck converter, and a few MOSFETs. Extremely simple, but [Debasish] is connecting the entire controller to the Internet with an ESP8266 module. It’s a great example of building something for much less than it would cost to buy the same thing, and a great example for something that has a chance at making the world a little better.
The simplest and easiest way to charge a battery with a solar panel is to connect the panel directly to the battery. Assuming the panel has a diode to prevent energy from flowing through it from the battery when there’s no sunlight. This is fairly common but not very efficient. [Debasish Dutta] has built a charge controller that addresses the inefficiencies of such a system though, and was able to implement maximum power point tracking using an Arduino.
Maximum power point tracking (MPPT) is a method that uses PWM and a special DC-DC converter to match the impedance of the solar panel to the battery. This means that more energy can be harvested from the panel than would otherwise be available. The circuit is placed in between the panel and the battery and regulates the output voltage of the panel so it matches the voltage on the battery more closely. [Debasish] reports that an efficiency gain of 30-40% can be made with this particular design.
This device has a few bells and whistles as well, including the ability to log data over WiFi, an LCD display to report the status of the panel, battery, and controller, and can charge USB devices. This would be a great addition to any solar installation, especially if you’ve built one into your truck.
This is [Debasish]’s second entry to The Hackaday Prize. We covered his first one a few days ago. That means only one thing: start a project and start documenting it on hackaday.io
Our love for solar projects continues on with this method to make your own solar panels. [Mike] built a 60 watt solar panel from individual solar cells he purchased off eBay. Procuring parts off of eBay normally causes others hardship when they try to duplicate the project, however in this case there are so many types of cells people can use to produce their own unique solar panel. Even cells that are extremely damaged my still be used, as in this example. To charge a 12 volt battery the number of cells in series just needs to be 16-18 volts, and the rest in parallel will supply more current. Charging a battery without a charge controller is not recommended, but commercial ones are easily had. Those not interested in jumping all the way in with solar may want to test the waters by building their own panel and putting it to use as a charging station for your portable gadgets.