Can Rewiring the Home for DC Power Increase Solar Adoption?

AC/DC evidently can just get along, long after Thomas Edison and Nikolai Tesla’s bitter war over standards favoring alternating current (AC) vs. direct current (DC) electricity in the early 20th century. Inside our solar homes, businesses and universities, to be exact.

That’s the plan and the party line for the public-private EMerge Alliance, whose DC Power Initiative to integrate solar DC power into the national infrastructure is now open for business.

“I wouldn’t give up my seat in the arena of electrical history just yet, as the battle of the currents is about to enter into its next round,” EMerge Alliance Chairman Brian Patterson told me. “Team Edison is making a comeback and this time the odds look strongly in their favor.”

Patterson feels confident because direct current “would enable homeowners to power their DC-driven electronics, appliances, LEDs and electric vehicles directly from solar panels, which natively produce DC power, rather than having to convert that power from DC to AC and then back again at the device level. Eliminating these wasteful conversions can dramatically improve the efficiency and return-on-investment of solar generation systems. Such systems, some that include power storage as well, have already proven themselves effective in commercial buildings, and could also give homeowners the choice of either conveniently storing excess DC power for later use or selling it back to the power company when the economics of either are favored.”

But converting an existing house to DC is not exactly a simple process, which explains why EMerge Alliance is governed by big names like Philips and Sylvania, with participation from titans like Cisco and Duke Energy, and advisory guidance from UC Berkeley and Lawrence Berkeley National Labs, and way, way more. Such an expansive solar tent is needed to take the four key steps for proper conversion, said Patterson.

“Studies must be completed to model the ideal configuration of such systems in the home,” he explained. “Actual pilot installations must be made in both new and existing homes to validate the models from the paper studies. Standards must be created and/or modified to allow the residential materials, equipment and construction industry to develop products that easily and economically integrate into complete systems in both new and retrofit construction scenarios. In particular, with retrofit construction, the standards developed must allow for incremental and opportunistic renovation and upgrade strategies.

“Intermediate stages of this type of evolutionary transformation need to address the necessary hybrid configuration that include both AC and DC power use in a single home,” he added. “Coincident with this applications standards development, any new configurations or components needed will need to be explicitly included in updated code and regulatory requirements. And the design, engineering and construction trades must be educated and trained to implement the new systems platforms.”

Patterson is hoping that a parallel process bringing DC power distribution more clearly into focus and adoption will help speed up that complicated process. It’s the mandate of the EMerge Alliance’s hybrid future, one that will hopefully not be as protracted and pointless as the last one in which Edison and Tesla battled for scientific and economic supremacy, a conflict the Department of Energy recently rebooted on Twitter. We’re going to need to get along much, much better than Tesla and Edison with climate change beckoning on our horizon.

“In the early going, the Edison team was sorely disadvantaged by not being able to make relatively convenient changes in voltage enabled by a relatively simple AC coil transformer, and of course the perfection of a constant speed AC electric motor, provided by Tesla, was the knock-out blow at that time,” Patterson said. “But so-called semiconductor solid-state technology has grown since then to dominate the load side of the electrical power system equation. The future of native DC electric generation, like solar, is bright.”

“Soon will be gone the days of the sole use of instantly dispatchable synchronous AC power,” he concluded. “The ability to store DC power in every level of a system will make issues like phase correction, VAR demand and line balancing things of the past. The milliwatt transistors of 1946 have grown into superpower isolated gate bipolar transistors of the 21st century.”

This article appeared at Solar Energy

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