It's that time again. Tesla (TSLA) investors are once again glued to a single number: vehicle deliveries. With the electric vehicle maker expected to report second-quarter delivery figures in the coming weeks—likely around July 2—Wall Street is debating whether demand has finally stabilized after a rocky start to the year.

But while deliveries will almost certainly dominate the headlines, there's another metric that might deserve a little more attention. Tesla's energy business is growing fast, and it could be becoming a much bigger part of the investment story.

Deliveries Still Matter

There's a good reason investors obsess over deliveries. They're one of the earliest signals of Tesla's sales performance and offer important clues about future revenue and profitability. The metric has become one of the most closely watched data points on Wall Street, often moving the stock before quarterly earnings are even released.

So much of the market's attention remains fixed on whether Tesla can reverse its recent delivery weakness. But focusing exclusively on vehicle volumes might mean overlooking a business segment that has quietly become one of Tesla's fastest-growing operations.

The Energy Story Keeps Getting Bigger

Tesla's Energy Generation and Storage segment has emerged as a significant growth engine. The division includes products like Megapack utility-scale battery systems and Powerwall residential energy storage solutions. Demand has surged as utilities, corporations, and governments invest heavily in grid modernization, renewable energy integration, and backup power infrastructure.

Unlike the automotive business, which continues to face pricing pressure and intense competition, Tesla's energy segment has delivered strong growth and improving profitability. The scale of the opportunity is becoming hard to ignore.

According to Reuters estimates, Tesla's energy generation and storage business could generate roughly $18.3 billion in revenue this year—nearly one-fifth of the company's expected total revenue. Just a few years ago, the segment was often viewed as a side business compared to Tesla's automotive operations. Today, it's one of the company's fastest-growing divisions.

While investors continue to debate vehicle deliveries, pricing pressure, and EV competition, Tesla's energy business is benefiting from a different set of tailwinds. Utilities are investing in battery storage, data centers are consuming more electricity, and power grids around the world are being upgraded to accommodate growing energy demand. Those trends have helped turn products like Megapack from a niche offering into a major source of revenue growth. The company's Megapack factory in California has been operating at scale, while a second Megafactory in Shanghai is expected to further expand production capacity.

Why Investors May Need to Pay Attention

For years, Tesla's valuation has been tied largely to expectations surrounding vehicle sales. That may be changing. While automotive revenue remains the company's largest business, energy storage is becoming a more meaningful contributor to overall growth. The segment is also benefiting from powerful long-term trends, including rising electricity demand, AI-driven data center expansion, and increased investment in grid infrastructure. Those trends could provide Tesla with another avenue for growth beyond vehicle deliveries.

That's why investors watching Tesla's next delivery report may want to look beyond the headline number. Deliveries will tell you how Tesla's car business is performing. But energy revenue may offer an increasingly important glimpse into where the company's next phase of growth could come from. If Reuters' estimate proves accurate, Tesla's energy business would be approaching the size of a Fortune 500 company on its own.