Tag Archives: off-the-grid

Take your essential appliances off the grid with this solar power controller


This system allows you to ‘UNplug’ from the grid during the day and re-plug at night.


In today’s ‘always on’ era, there are over 100 million refrigerators, Internet modems and laptops running on fossil fuels in the United States alone, all of which adds roughly 33 billion pounds of CO2 to the atmosphere annually. That is the equivalent of four coal burning power plants, just to put things into perspective. As a way to curb this never-ending problem, Markus Löffler has developed a solution that starts with taking essential household appliances off the grid during daylight hours.

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The idea for this project first came about after the Maker and his family suffered a power outage that left his home in total darkness and their refrigerated food spoiled. Upon brainstorming, he decided to absorb the endless sun of Southern California through a series of solar panels and take his refrigerator off the grid during peak hours of the day, which also happen to be when energy costs and greenhouse gas emissions are the highest. What’s more, the aptly named UNplug system automatically reverts back to electricity at night.

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Now live on Kickstarter and a recent entry in this year’s Hackaday Prize, UNplug supplies automatic uninterrupted power with built-in surge protection by controlling the power source that goes to an appliance, switching between the grid, solar power and batteries. Meaning, should a thunderstorm, hurricane or a tree falling on a line cause a power outage, the solution is capable of switching back via battery. This lets users keep their most critical home equipment up and running in a time when they’re needed most, whether it’s the lights, security monitors, smoke detectors or phone chargers. One solar panel is enough to take a refrigerator, laptop and modem off of the grid.

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The unit is comprised of three main functional blocks: a120V AC unit, a 12/24V DC unit, as well as the sensors and microprocessors. Speaking of which, two configurations are available. The first employs an Arduino-compatible ATmega328 controller without the need for a Wi-Fi signal, while the second uses a Spark Core to wirelessly send data and sync with IFTTT recipes.

“The UNplug firmware will be pre-installed onto the processors so each unit is ready right out of the box. But you can even go ‘fully hacker friendly’ and download and compile your own programs. There is an Arduino and Spark compatible C-library that allows you to program your own functionality and go be beyond the intended use. There are two interfaces (Serial and I2C) to wire connect the unit to other hardware like the Raspberry Pi,” Löffler writes.

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In order to completely construct the appliance power system requires a 12V or 24V power inverter, batteries and at least 250W of solar panels. An online dashboard allows the user to monitor energy usage, cost savings and other metrics from just about anywhere. These algorithms and programs are all open source and available on Github.

“UNplug is essentially an Automatic Transfer Switch that switches a load between two sources. It automatically switches when it senses one of the sources has lost power,” the Maker notes. “The ATS will automatically tell the inverter to start. Once the ATS sees that the inverter is ready to provide electric power, the ATS breaks the home’s connection to the utility grid and connects the inverter. The inverter supplies power to the electric load, but is not connected to the electric utility lines.”

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What’s nice is that thanks to its modular design, each component can be updated independently. This includes adding more solar modules and batteries, replacing the inverter with a more more efficient unit, swapping out the universal socket MCU with a Bluetooth-enabled controller, integrating a cellular network, and receiving automatic firmware updates via Wi-Fi.

UNplug isn’t only limited to in-home use either; in fact, it can be implemented pretty much anywhere, from RVs and campers to boats and cabins. Head over to its Kickstarter campaign, where Löffler is currently seeking $55,000. Delivery is slated for October 2015.

This DIY device will reduce your energy footprint


Take your essential appliances off the grid with an Arduino-based solar UPS controller. 


For his entry in the 2015 Hackaday Prize, Markus Loeffler recently developed a shoebox-sized UPS controller that can be used for solar energy on a minimal level. At the moment, the unit is capable of powering a handful of ‘always on’ household items like the refrigerator, Internet modem and home security system, thereby enabling users to take these appliances off the grid.

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“It all started during a stormy winter in 2011 when my power was out for 4 days. I was thinking: if I only had some independent power source available. Maybe I would not have lost all my food in the fridge,” the Maker writes.

The device is not only modular and scalable, but can connect to any inverter, battery, charge controller and solar panel up to 1500W continuous power. The controller is essentially an Automatic Transfer Switch (ATS), which switches a load between two sources and will automatically be activated when it detects one of the sources has lost power.

“The controller is doing transfer switching between the solar powered inverter and main utility power to optimize battery life and maximize solar energy usage. It is also monitoring phase shift between utility power and inverter and only switches in phase-sync to protect your equipment.”

During day, the solar panel delivers power to the inverter and the excess energy charges the battery. At night, the inverter is turned off and the utility power from the wall outlet passes through. In the event of a blackout, the controller immediately kickstarts the inverter to power the 120V outlet. Meanwhile, UPS mode powers the inverter continuously for standby by drawing energy from the utility power to run the inverter and conserve battery life.

According to Loeffler, the run-time for the battery-operated UPS mode is contingent upon the type and size of batteries used, the rate of discharge, and the efficiency of the inverter. A wide variety of inverters and battery sizes can be combined, ranging from 10AH @ 12V to 5000AH @ 24V using common lead-acid batteries. The controller features a simple menu driven setup mode where levels for different kinds of battery types can be adjusted.

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As for hardware design, Loeffler has “gone from breadboard proof-of-concept into actually manufacturing a small run of PCBs. Most of them are at friends houses who help beta-testing the system in combination with various inverters and charge controllers.”

The latest iteration follows in the footsteps of its initial ATmega2560 powered prototype, which the Maker had put to good use during Burning Man. The newer, more compact design replaces the megaAVR MCU with a simple plug-in connector for either an Arduino Nano (ATmega328) or Spark Core board.

The revised UPS controller now packs a 24VDC supply for external hardware with a max draw of 20W, header pins to communicate with other hardware, a buzzer, a temperature sensor, a 120V-24V transformer, six heavy-duty AWG terminals for connections, a 120V DPDT relay to switch between the two power sources, a power MOSFET bank to switch up to 50A @ 30VDC, as well as AC terminals for 10A @ 120VAC 60Hz.

“All parts together costs less then $900 and you can build a solar powered uninterruptible power supply (UPS) that generates you daily 1kWh or more,” Loeffler adds.

The Maker has put the system to the test by piloting the most recent controller throughout his household, which is being monitored as we speak. At the moment, the controller is powering his refrigerator, TV, stereo, phones and other mobile devices, laptop, desk lamp and IP setup.

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Interested? Head over to the project’s official Hackaday.io page to learn more.

Recycled greenhouse goes off-the-grid with Uno

Students at the Kennebunk High School in Maine have successfully constructed and maintained an off-the-grid greenhouse using Atmel-based Arduino boards, solar panels and a sprinkler system.

Photo Credit: Alex Acquisto, Kennebunk Post

According to Alex Acquisto of the Kennebunk Post, Arduino Uno boards (ATmega328 MCU) are deployed in the greenhouse as soil moisture sensors.

“If the soil is too dry, the Arduino will trigger the battery-powered sprinkler system, also designed by students. The greenhouse is powered exclusively by a solar panel and depletes no other electrical sources, thus it is considered off the grid,” he explained.

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“As the soil moisture sensor triggers the sprinkler system if it’s too dry, students are preparing a temperature sensor to test the heat level inside the greenhouse. If the heat becomes too high, the goal is that the window, by programming another Arduino robot, will peel open on its own.”

Acquisto also noted that much of the greenhouse material is recycled.

“The six rain barrels were at one time used by a restaurant to store soy sauce, [while] the screen window students [recently] began installing was pulled from a dumpster behind the school,” he said.

Photo Credit: Alex Acquisto, Kennebunk Post

“It sounds like the work of trained professionals, but most of the students only became familiar with what it takes to maintain a greenhouse this year.”

In related news, Roberts Farm in Maine is currently testing an inexpensive Arduino-powered agricultural system that automatically monitors and waters crops. As Scott Taylor of the Lewiston-Auburn Sun Journal reports, the system has already proven itself by allowing Earl Morse, a retired teacher and volunteer at the Roberts Farm project, to successfully harvest a crop of spinach grown last winter in an exterior green house.

“[The system] keeps watch on the soil temperature and interior moisture through freezing temperatures and darkness. It works, not with hundreds of dollars worth of computer equipment but hobbyist-grade, [Atmel-based] Arduino boards,” wrote Taylor. “While the farm’s goal is teach local kids about growing their own food and the technology behind farming, Morse hopes to create an automated system that not only gives the plants light and keeps them watered but extends the growing season — and does it cheaply.”

According to Taylor, Morse hopes to publicly release the open source, Arduino-based system this fall.

“What we’re trying to do is make all the mistakes now, so it’s ready for everyone else to use,” said Morse.”That’s basically what we’re trying to do, make a farm robot. Maybe a robot farmer.”

Interested in learning more about farming with Atmel-based systems? You can browse through some of our previous stories on technology and farming including “The Internet of Things, Stalk by Stalk,” “Smart Urban Aquaponics in West Oakland,” “DIY Farming with Atmel and Arduino,” “Open Source Aquaponics with APDuino,” Agricultural Monitoring with Atmel AVR
” and “Arduino-Based Farming in Maine.”