The Tesla Powerwall home battery system should finally be appearing in the basements and garages of Canadian homes this summer, giving people a chance to store solar power or time-shift their electricity consumption. But there may be sticker shock: Installation is likely to double the $3,000 (U.S.) hardware price.

Announced with great fanfare about a year ago, the sleek electrical storage units have been slow to trickle out of the "gigafactory" built by Tesla founder Elon Musk in Nevada. Just 2,500 were delivered worldwide in the first quarter, and Canada has received only a handful so far.

In Canada, the Powerwall is being distributed by NRStor Inc., the energy storage developer led by former Home Depot Canada boss Annette Verschuren, in a joint venture with smart grid software company Opus One Solutions Energy Inc.

Story continues below advertisement

Last spring, NRStor said it was going to sell the units here early in 2016, although that timetable has slipped.

"We're working towards a public launch in the summer," said Bob Atkinson, president of M Power Energy Solutions, the NRStor division that is distributing the Powerwall. "The focus now is really building out all the plumbing," which includes making sure the product pipeline from the manufacturer is established, putting in place a payment and financing system, and ensuring installers know what they are doing.

The Powerwall isn't just hung up on the side of a garage. The connections can vary depending on how the unit is being used and what the local electrical utilities require.

"Some [potential customers] have seen the Elon Musk video, and they think 'I plug this in and I'm off the grid,'" Mr. Atkinson said. "It's not quite that easy." Installation must be done by a professional.

NRStor has lined up about 15 electrical contractors so far, and they are being trained to install the Powerwall. Some are already familiar with installing electric-vehicle chargers or solar panels, so have some experience with related technology.

NRStor has so far received about 25 Powerwall units and some are being installed in test situations before the larger volume of shipments from Tesla begins. That's likely to happen within the next three months.

While Tesla set the price of a seven-kilowatt-hour Powerwall at about $3,000, that doesn't include installation or the cost of an inverter – the device that switches power back and forth between direct current used in the battery and alternating current used by home appliances. The actual installed price has not yet been determined, Mr. Atkinson said, but it will likely be roughly double the hardware cost.

Story continues below advertisement

Despite that hefty price tag, "a few thousand" customers in Canada have expressed interest in buying a Powerwall, he said, although none has plunked down any money yet.

While the Powerwall can store electricity generated by solar panels for consumption at night, many people are expected to use the device as a backup system to maintain power flow in a power failure. Others, in places where there is time-of-use pricing, may use the Powerwall to store power when electricity is less costly, then use it when prices peak.

For some people who have older battery technology to store power from solar panels, the streamlined lithium-ion Powerwall could be a step up. "We are getting lots of inquires from [people with] off-grid cottages, where they have jerry-rigged the basement with lead-acid batteries and they are looking for a safer solution," Mr. Atkinson said.

Critics have pointed out that with a capacity of just under seven kwh, the Powerwall will not hold enough electricity to run a home for a day. (In Canada the average daily consumption is about 30 kwh.) But it would be enough to keep crucial components such as lights, a refrigerator and cellphone chargers going for a period of time. There are also other backup batteries available, although they don't have the cool look of the Powerwall.

And the unit isn't small. It weighs almost 100 kilograms and is one metre wide and 1.5 metres high.

Shane Johnson, who runs SolarPanel.ca, an Alberta company specializing in off-grid solar installations, says he will remain skeptical of new products such as the Powerwall until the technology is proven. For most of his solar sites, he uses a kind of lead-acid battery called "absorbed glass mat" that he says is "really proven, sealed and maintenance free." The battery arrays are heavy and take up a lot of space, he said, but that's not usually an issue in a permanent off-grid solar setup. As for newer technology such as the lithium-ion Powerwall, "it has to go through the hoops before I get excited about it," he said.