Off-the-Grid Home Stores Energy and Automates Load Shedding

December 3, 2012
By
SniderHome Exterior

This Net Zero home not only produces all its own energy, it stores and automates it as well. Photo by Mike Negron

We hear it all the time: “I’d like to go off the grid.” “Produce all my own power—and store it.”

These declarations come from a wide swath of people. They come from those looking at modest solar photovoltaic (PV) investments to power their homes with grid-tied systems and realizing that when utility power goes out, so does their system’s ability to produce power (backfeeding power on the lines is a hazard to linemen trying to repair a grid). Declarations of grid independence also come from people who are fed up with losing power for days or weeks during storms that are becoming more prevalent and more intense.

Yes, we’re thinking of Hurricane Sandy victims of a decimated power infrastructure, but also of the hundreds of thousands whose power goes out regularly in big and not-so-big storms and wait for days while large and overtaxed utilities try to restore power. (Dial up anyone at random in Southern New Hampshire and ask about this, and you’ll likely get an earful.)

And more and more, we’re seeing homes designed and built not just with net-zero (producing your own energy) in mind, but with storing energy as well.

Way Off the Grid

Snider Home Solar

A 16.6-kw solar array provides all of the home's electricity, which is stored in a bank of batteries. Photo by Mike Negron

Tim Snider’s vacation home north of Flagstaff, Ariz. was designed to be off the grid from the start. It’s powered by a large solar PV system, but it also stores the energy collected in a bank of batteries that are governed by a system to optimally charge them automatically—and automatically conduct load-shedding when power supplies are low.

That’s not just net-zero, but off-the-grid, baby. And it’s by far the coolest off-the-grid application we’ve seen thus far.

How off-the-grid is it? Way off. Snider’s home is miles from the nearest power lines, so the home had to build to be completely self-sustainable. He started the design thinking of powering his home with liquid propane generators. He decided to add 16.6 kilowatts of solar PV to the mix, even though powering the home with generators might have been cheaper. After all, if you’re going to power a home, you may as well take advantage of Arizona’s abundant sunshine.

Following are the green-tech highlights from a feature article written on the house for Electronic House magazine:

Energy Producers

Snider Home inverters

Six OutBack inverters (center) and a bank of 48 batteries (left) convert and store the electricity. Photo by Mike Negron

The 72-panel solar PV array produces 16.6 kw, with 260 kWh of battery storage, enough for about 36 hours of use, says Snider. A solar thermal system heats water for domestic use and the home’s radiant-floor heating system, and a backup generator and water heater for times when all the power from the sun isn’t enough.

The home consumes about 100 kilowatt hours (kWh) of solar energy a day when the homeowners are in residence—some of that just from keeping the backup generators warmed and ready to go.

Control and Monitoring

Snider Home eMonitor

The eMonitor display shows energy production and consumption at the circuit level with easy-to-read graphs and charts. Note the Utility Meter reading is 0.

Custom electronics installation firm AVDomotics in Sedona, Ariz., worked with Snider to design and install a Crestron home control system and Powerhouse Dynamics‘ eMonitor that could monitor the power production of the solar system and power consumption, battery levels, and cut loads automatically when necessary. Crestron’s AV2 processor handles the operation of the home’s lighting, audio/video gear, thermostats, security system, exterior safety shutters, and pumps for the well and septic. It’s paired with the eMonitor system — with its dynamic web-based interface available on a computer, Crestron touchpanels, iPads and Tim’s iPhone — to show user-friendly charts and graphs of the home’s production of solar power and how much energy is being consumed. Tim can also see how much power is available as stored energy in the batteries from Crestron’s touchpanels and apps.

Programming for Monitoring

SniderHome Crestron display

Crestron's TPMC-8L in-wall touchpanel can even display gas and water tank levels. Photo by Mike Negron

AVDomotics created its own “modules” within the Crestron platform to enable the automation system to communicate with an OutBack Mate2 solar inverter control system. The company also programmed the Crestron system to monitor the level of liquid propane and water available in their respective tanks. A high-end Uponor in-floor radiant heating system, which relies on water heated by the roof’s solar thermal panels and liquid propane-fueled hot water in the backup tank, was integrated into the Crestron control system as well. All of these systems, plus the security system, lights and A/V gear, can be operated not only from Tim’s smartphone but from three Crestron  in-wall TPS-6L and one TPMC-8L touchpanels located throughout the home, in addition to three TPMC handheld remotes and three iPads using a Crestron app.

 

Automated Load Shedding

Snider Home Batteries

The 48 batteries can store about 260 kWhs of power. Photo by Mike Negron

The Crestron system can also perform much-needed load shedding, in which it turns certain devices down or completely off to save energy. When the house is unoccupied, for example, the well and septic pumps shut off, and if there isn’t much juice left in the solar system’s storage batteries, the lights dim to 75 percent.

“The energy management is the best part of the system. The thing that I use the most is checking on the PV system and seeing how much energy we’re producing, and I can do that from anywhere in the world,” says Tim. “The first year in the house, we were learning all about it, but now my confidence level is high and I don’t worry about the place as much as I used to.

“With homes like this, we’re pushing the envelope not only on how much energy we can save, but how reliable and luxurious solar systems can be,”? says Charlie White of AVDomotics.

There’s Entertainment, Too

Snider Home iPad

iPads control everything from A/V to lights to energy. In the living room, QPD motorized speakers lower from the wood soffit to remain nearly invisible (above TV). Photo by Mike Negron

The Sniders are not without entertainment. Twelve zones of audio and eight TVs, including a surround-sound system in the family room, are served by home control company Crestron’s ADMS Intermedia Delivery System media server. Crestron’s DigitalMedia switching technology delivers audio and video content to different areas of the house via the company’s DigitalMedia fiber solution, with fiber-optic wires terminating at each of the home’s TVs.

Energy-Smart Upgrades

Snider Home Bar

LED lights cast a warm glow around the bar. Photo by Mike Negron

After construction, the owners realized they could save even more by swapping their incandescent lights for LEDs (light emitting diodes). White says it cost about $3,500 to replace the existing bulbs with Philips and Color Kinetics LEDs, but was well worth it, as the homeowners would have had to spend $10,000 more on solar panels to run the incandescent lights. In essence, they have already received an immediate return on their investment, and then some.

The ceiling fans that help cool the house may be in for an upgrade, too. AVDomotics may tie them to indoor and outdoor temperature sensors so they can turn on and off automatically.

“There’s a lot more we can do,” adds Tim. “I want some applications to only come on when batteries are full and there’s still some sun to produce power. … We’ve gotten our propane consumption down to a low level, but now I want to manage it so I don’t have to consume any carbon fuel there.”

The Far Away Button

When it’s time to leave for the season, the owners only have to push an away button on any of their Crestron controllers turn off everything. Then they can hop in the car, take a last look at their remote retreat, and press another button to roll down the aluminum shutters over all of the first floor windows and doors for safety and security.

For added assurance, the Sniders and AVDomotics receive alerts from the eMonitor and Crestron systems if any circuits are on or if there’s a problem with a system in the home. Emails are also delivered to AVDomotics twice a day with a status report of the system, which helps the custom electronics dealer proactively remedy a situation before it becomes costly or dangerous.

This article is based on a feature article in the July-August issue of Electronic House and can be found here.

Electronic Systems: AVDomotics, Sedona, Ariz.

Design/Build: Wm. King-Colegrove, Flagstaff, Ariz.

HVAC: Intermountain Plumbing, Mechanical and Solar, Flagstaff, Ariz.

Solar: Prometheus Renewables, Flagstaff, Ariz.

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One Response to Off-the-Grid Home Stores Energy and Automates Load Shedding

  1. rex turner on February 18, 2015 at 12:09 pm

    What is the cost

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