FLNC vs STEM: Which Is the Better Buy in 2026?

Same yardstick, side by side (as of August 2026). Valuation lined up like this is most meaningful for two names in the same corner of the market, which these are. Figures are approximate; verify before investing.

The metrics above tell you which is the marginally better business. The bigger risk for most people is not picking the slightly worse stock, it is over-concentrating. FLNC and STEM share themes, so owning both, or adding either to what you already hold, can quietly push a large share of your portfolio into one bet.

This is the part a generic comparison page cannot answer, because it depends on what you own. Connect your brokerage and Walnut shows your real, combined FLNC and STEM exposure, flags overlap with your existing positions, and tells you if adding one would tip you past a concentration you are comfortable with, read-only by default, with your login staying at your broker. Walnut is not an investment adviser.

Fluence Energy is a leading provider of grid-scale battery energy storage systems and related software. The company was formed as a joint venture between Siemens and AES, two large players in power and utilities, and later listed publicly. Fluence designs, builds, and services large stationary battery installations that utilities, developers, and grid operators use to store electricity and discharge it when demand or prices are high. It makes money primarily by selling complete storage systems (hardware, integration, and engineering), and increasingly through recurring software and long-term service agreements. Its Fluence IQ software platform helps owners optimize when to charge and discharge batteries in power markets. Headquartered in Arlington, Virginia, Fluence operates globally, with major projects across the Americas, Europe, Asia, and Australia. It sits at the center of the energy transition, where renewables and grid reliability drive demand for storage.

Full FLNC guide

Stem, Inc. is a clean-energy technology company that provides AI-driven software and services for battery energy storage and solar assets. Its platforms include PowerTrack (the enterprise optimization and monitoring platform formerly branded Athena) and PowerBidder Pro, an AI-enabled tool that helps asset owners and traders bid storage into wholesale power markets such as ERCOT. The company earns money from software subscriptions, managed and edge-device services, and, historically, hardware resale. Beginning in late 2024, Stem announced a strategic realignment to move away from reliance on low-margin hardware toward a software- and services-led model, aiming to lift gross margins, build recurring revenue, and grow annual recurring revenue (ARR).

Full STEM guide

Both fit overlapping themes, but they are not interchangeable. The useful comparison is which set of drivers and risks you want exposure to.

• FLNC drivers: Grid-scale storage demand; Recurring software and services.
• STEM drivers: Software and SaaS transition; Growth in energy storage markets.

A faster-growing, richer-valued name usually swings harder, so it suits a longer horizon and a higher tolerance for volatility; a steadier, more cash-generative business suits a more conservative or income-minded investor. The honest test is which set of risks you could hold through a drawdown: Fluence operates in a competitive, capital-intensive market where margins have historically been thin and projects can be lumpy. For STEM, the central risks are that Stem is a small-cap turnaround with a modest revenue base, a history of losses, and a debt load that has pressured its balance sheet, and the software transition is still unproven at scale.

Growth-minded investors who believe the theme has years to run tend to accept the richer multiple for more upside; value-minded investors lean toward the cheaper forward earnings and steadier profile. Pick FLNC if you believe its drivers more; STEM if you believe its. Many investors hold both, but since they share themes, that is a concentrated bet, not diversification. Decide deliberately and check overlap. For the full detail, see the FLNC and STEM guides.

FLNC. Fluence is valued as a growth-stage energy transition company rather than on stable earnings. Investors focus on revenue growth, backlog, and the path to durable profitability and recurring software revenue. Margins and cash flow have been volatile, so the valuation reflects optionality on storage demand more than current earnings power.

STEM. Figures are approximate and tied to the asOf date; verify live numbers before acting. Stem is a small-cap turnaround mid-pivot from hardware to software, so results can be lumpy, guidance ranges are wide, and reported GAAP results differ meaningfully from adjusted EBITDA. The 1-for-20 reverse split in June 2025 also changed the share count and per-share figures, so be careful comparing pre- and post-split numbers. Confirm the latest revenue, ARR, cash, and debt directly from filings before drawing conclusions.

Headline figures (approximate, early 2026): FLNC shows revenue (ttm) ~$2.5 to 3 billion, gross margin ~low double digits, improving, operating margin ~near breakeven, order backlog ~multi-billion dollar pipeline; STEM shows q1 2026 revenue (software, services, edge hardware) ~$29 million, up modestly year over year; PowerTrack software revenue up ~16%, fy2026 revenue guidance Roughly $140 million to $190 million (a wide range signaling uncertainty), adjusted ebitda Several consecutive positive quarters; FY2026 guided to modest positive adjusted EBITDA (roughly $10 million to $15 million), year-end arr (guided) Mid-$60-million range (~$65 million to $70 million).

FLNC and STEM are related but distinct: same themes, different businesses and risks. Neither wins in the abstract; the right pick is whichever thesis you actually believe, sized so you are not over-concentrated in one theme. Walnut can show your combined FLNC and STEM exposure against your real portfolio. It is not an investment adviser.