Over the last decade, Sunverge has become a preferred provider of home solar-battery systems to utilities. It rivals Tesla in scope and scale of its deployments, if not in its marketing hype. 

But just like Tesla, the startup has seen its share of struggles, albeit of a different scope.

While Tesla is seeking mass-market acceptance for its Powerwalls (and achieving decidedly mixed results in terms of keeping production on track with its sales) Sunverge has shifted from making its own battery units to providing software to utilities, in hopes of finding a niche as a trusted virtual power plant (VPP) platform provider. 

On Tuesday, the company announced three more utility customers, including two with some advanced interest in solving the solar-storage grid challenge. 

The first, Arizona Public Service, plans a neighborhood-scale installation of Sunverge One battery-inverter units, along with home energy controllers, to help balance the rising neighborhood-level swells and sags in customer-generated solar power throughout the day. 

This pilot is the latest in the utility’s long-running study of storage, power electronics and communications to manage its rising tide of customer-generated solar power. The first round, a joint effort with the Electric Power Research Institute (EPRI), has been testing megawatt-scale grid batteries, as well as more than 1,600 advanced inverters. This next phase, known as the Solar Innovation Study, involves distributed energy resources at the residential scale, including rooftop solar, load controllers, HVAC systems and battery storage. 

The Sunverge One, the company’s basic 6.4-kilowatt, 11.8-kilowatt-hour lithium-ion battery and inverter unit, has a decidedly low-key feel, suggesting more of an outdoor air conditioning unit than Tesla’s futuristic turtle-shell wall mounting. That's partly because it's meant to be installed outdoors, and is rated to withstand the typical utility ranges of heat, cold and rain, and partly because Sunverge seeks to involve the customers as little as possible in the unit’s overall operation, beyond informing them how much it’s earned them over the course of time. 

Sunverge has been quietly building its customer base for more than a decade, starting with early tests for hometown utility Sacramento Municipal Utility District, and since spanning to include more than 1,000 customers in five countries. Many are are in California, although the company has been working in Australia, where utility AGL is planning to deploy up to 1,000 units for a residential virtual pilot plant project. 

But AGL has only deployed 250 units after the utility to changed its approach to the project. Meanwhile, a large-scale project with Con Edison in New York City was postponed this year, after the utility failed to reach an agreement with city fire department officials on how to manage the safety risks of lithium-ion batteries. 

Sunverge has long said that it didn’t plan to compete head-to-head on battery manufacturing with Tesla, let alone the handful of multinational electronics giants that are driving down costs in the industry. Early this year, it started offering support for other batteries on its VPP platform. But it also laid off manufacturing plant workers earlier this year, and earlier this month replaced its longtime CEO Ken Munson with CTO Martin Milani, formerly of grid software provider Nexant. 

Arizona Public Service is ordering relatively few batteries from Sunverge. Only 10 homes in the pilot will be equipped with Sunverge One units. But another 65 customers will receive Sunverge’s energy management gateways, which allow the company to centrally manage smart thermostats along with solar, storage and power electronics, to do things like shift air-conditioning energy demand to earlier in the day when solar generation is peaking. 

This kind of demand response is much cheaper than batteries in cost per kilowatt-hour, making it a plus to the utility -- although not necessarily to an energy storage vendor trying to max out its sales. Meanwhile, the batteries will be available to mitigate sudden, unexpected shifts in supply-demand balance, manage sags and spikes in grid voltage, and perform other tasks that smart thermostats can’t accomplish. 

Sunverge has taken a similar whole-home energy management approach in its long-running project with Tennessee electric cooperative Glasgow Electric Plant Board, Starting in 2015, the utility deployed 165 customer-sited energy storage systems from Sunverge, along with 345 hot water heaters from General Electric and smart thermostats from ecobee. The municipal utility uses its existing broadband to monitor and manage these combined assets between valleys and peaks in demand, preheating water heaters in winter and dynamically adjusting thermostats during summer months. 

The other two utilities that announced work with Sunverge this week are testing its systems on a much smaller scale.

The first, Florida’s Lakeland Electric, will install one system at a commercial site to test its ability to shave peak demand charges while also supporting grid needs.

The second is with Vermont’s Green Mountain Power, a utility that’s put a good deal of investment into testing different stacks of value for solar-storage systems, and a user of Tesla batteries as well. Unlike the first two announcements, this one involves an existing installation, a single Sunverge One unit, which kept three commercial-grade refrigerators and other key equipment running at a Farm & Wilderness summer camp for about seven hours during a recent power outage.

It's hard to make a dent in the industry when remaining stuck at deployments of that size. Can Sunverge get beyond pilots with any of its new customers?