SAN FRANCISCO — As California faces massive wildfires and extensive power failures, Elon Musk has taken to Twitter with his latest cause: equipping residents here with solar panels and giant batteries to power their homes.

In a series of tweets last week, the Tesla chief executive made a simple case to affected state residents: buy his solar and battery setup to ride out the next disruption. Power shut-offs from the local utility, Pacific Gas & Electric, will only become more prevalent over the next decade. And solar-equipped homes are more efficient and better valued on the housing market. He even offered a $1,000 discount to those affected by days of power failures caused by wildfires.

“Order Tesla Solar + Powerwall battery for 24/7 clean power & no blackouts!” Musk tweeted, adding a link to the solar section of Tesla’s website.

Tesla is best known for its car business, which has put electric vehicles into the hands of hundreds of thousands of people, but it has also made a significant bet on solar power and energy storage. It acquired rooftop solar installer SolarCity in 2016 in a $2.6 billion deal and markets products including solar-integrated roof shingles, rooftop solar panels and battery-based home electricity storage.

But solar panels with an accompanying Powerwall battery typically can only keep a home running for around a day or two during a blackout, requiring smart use of power-sucking appliances like dryers to keep them going. The cost of the setup also ranges in the tens of thousands of dollars.

Musk’s tweetstorm late last month on the benefits of solar power and energy storage is just one of a string of tech companies’ offers to help with a disaster in their own backyard — in some cases to a mixed reception.

Airbnb rolled out what it calls its Open Homes program, providing free lodging to fire victims, although technically the homeowners are the ones donating their spaces. Facebook said it was deploying its Safety Check function to let users mark themselves safe, and it committed $250,000 to recovery efforts. And Lyft provided two ride credits up to $15 each to fire victims in California.

Non-tech companies were also offering services, including U-Haul with free 30-day storage. Verizon and AT&T are also giving affected customers unlimited usage of calls, texts and data.

The companies made the offers as officials forecast that the fire season this year could stretch into December and fires continued to rage. In Northern California, the Kincade Fire swept Sonoma County, while fires including the Tick, the Easy and the Getty blazes erupted in Southern California. By Tuesday, officials said the Kincade Fire had burned nearly 80,000 acres and was 84 percent contained. Thousands of people were displaced by the fires and evacuations, and hundreds of structures were damaged or destroyed.

The companies need to walk a careful line, business school professors said. Although intentions may be good, they can also send the wrong signal — profiting off disaster.

“It could be perceived as opportunistic behavior,” said Charles D. Lindsey, associate professor within the University at Buffalo’s School of Management. “Even if it’s helping — if it’s seen as being opportunistic and taking advantage of people in a time of crisis, that’s where companies really need to think of areas to meet consumers halfway."

Tesla did not respond to multiple requests for comment.

Airbnb’s Open Homes program is available to fire victims through Thursday. Through the program, homeowners can opt to let people stay in their homes at no cost — and are ultimately the ones taking the risk of allowing them to remain indefinitely, without compensation.

Airbnb invests $25 million annually in its disaster response program, including for salaries and other operational costs, said Kellie Bentz, the company’s head of global disaster response and relief. And it donates to organizations that help match displaced victims with Airbnb properties near disaster sites.

Facebook has said it is collecting aggregated and anonymized data from its disaster maps to share with emergency response organizations such as Direct Relief. The company has faced some criticism for its donation of a quarter-million dollars; the median home value in Sonoma is $737,900, according to Zillow, and the wildfires’ damage was estimated at $25 billion, according to Bloomberg News.

Emily Dalton Smith, Facebook’s head of social impact product, said in a statement that the company has learned that providing those affected by a disaster with tools and help from the company’s larger network is the best way to support them. “Over the past two years, our tools have helped empower the community to fundraise for wildfires across California, coming together to raise more than $11 million for recovery and relief,” she added.

When it comes to Musk, the promises he made contain inherent risks, marketing and business experts said. Solar storage costs tens of thousands of dollars, an unaffordable prospect for many, and doesn’t alone allow for energy independence without substantial investment.

Last week, Musk tweeted an offer of a $1,000 discount for Tesla’s solar and Powerwall battery product, which costs $15,000 to $35,000, according to Tesla’s website. In reality, it’s a $700 discount on those prices, which factor in federal tax incentives available to all U.S.-based solar adopters — and the $1,000 discount applies to the base price.

“We don’t make much money on this product, so $1000 actually means a lot,” Musk tweeted. Musk also briefly changed his Twitter bio to “Tesla.com/solar for clean power & no blackouts."

Rooftop-mounted solar and battery storage are a pricey way to go about energy independence, said Ian Hiskens, a University of Michigan engineering professor who specializes in power system dynamics and grid controllability.

“If current economics were important then you’d just go to Home Depot and buy a little fuel-powered generator — and that’s a horrible thing for the environment — but that’s gonna be a cheaper thing for the consumer,” he said.

A fuel-powered generator typically costs between a few hundred dollars and a few thousand, depending on the size.

Figuring out how to deliver services free would be more helpful, said Jeffrey A. Sonnenfeld, senior associate dean of the Yale School of Management, whose work examines company leadership and corporate governance. Any product “should sell itself by people’s recognition that this is the solution — this is not a marketing opportunity.”

He contrasted Tesla’s approach with the more understated efforts of such companies as Home Depot and Generac Power Systems, which can count on an uptick in business but do not openly tout their products and services to disaster victims. When Hurricane Maria devastated Puerto Rico in 2017, he noted, Royal Caribbean canceled routes and deployed ships with supplies and evacuated victims from territories that were struck, conducting thousands of evacuations, according to its website.

Tesla was being exploitative, Sonnenfeld said, by touting its premium products during the crisis.

Musk hasn’t shied from the spotlight in times of disaster, which has at times gotten him into trouble. He was exploring ways to assist with the international effort to rescue a boys’ soccer team trapped in a northern Thailand cave before he called a rescue volunteer a “pedo guy” on Twitter and later a “child rapist,” leading to a defamation lawsuit that is going to trial later this year.

He also has gotten in trouble with company-related statements, including a Securities and Exchange Commission lawsuit against him and Tesla last year over a tweet in which Musk claimed that he had “funding secured” to take Tesla private at $420 per share. The claim resulted in his removal as Tesla chairman as part of a settlement and separate $20 million fines against him and the company.

Musk’s online posts indicated that there had been a surge in interest in the products. He tweeted late last month that the company was prioritizing California installations over other locations.

“Very likely that a home with clean power that’s lower cost than utility, plus blackout protection via Powerwall, will have a positive effect on value,” Musk tweeted Oct. 21.

Musk announced a separate commitment recently, pledging $1 million to an effort, #TeamTrees, giving the $1 per tree donations to the Arbor Day Foundation to plant 20 million trees around the globe by 2020. He changed his Twitter display name to “Treelon.”

On Friday, in an unrelated post, he said he was leaving Twitter.

“Not sure about good of Twitter,” Musk wrote, followed by a tweet that read, “Going offline."

He tweeted again Monday, after taking the weekend off.

Greg Bensinger contributed to this report.