Two oversized MPPT inputs, a genuine technical choice
The Stream accepts up to 1200 W of panels split across two independent MPPT inputs (600 W each), for a grid output capped at 800 W. This oversizing on the solar side isn't just a marketing argument: it captures more power early in the morning, late in the day, or in low light, and allows installing two panels facing different directions, east and west for example, without the less exposed one penalizing the whole system.
The 800 W output cap remains an adjustable software setting, not a physical hardware limit, and it can be lowered depending on local regulations.
The actual conversion efficiency
Spec sheets mention peak efficiencies around 95 to 97%, but the actual efficiency stands rather between 90 and 96% depending on the power drawn, averaging around 93 to 94%. That's an honest result, consistent with the rest of the microinverter market, but below the more flattering figures sometimes highlighted.
What the advertised "91 € in annual savings" is really worth
The manufacturer advertises up to 1140 kWh produced per year and around 91 € in annual savings depending on the installation. This figure comes from a simulation based on PVWatts data from NREL, the US national renewable energy laboratory, combined with a reference electricity rate: it isn't a real measurement on a typical household. A noticeably different order of magnitude, around 800 kWh and 127 €, comes out of different calculation assumptions. No French usage feedback with figures over a full year has been found to date to confirm either of these orders of magnitude.
The Eco-AI assistant, an advanced paid feature not disclosed as such
The EcoFlow app offers peak/off-peak hourly scheduling and an assistant called Eco-AI. Its most advanced functions, however, are billed by subscription, at a rate of around 3.90 € a month, information that appears neither in the headline pitch nor in the product's commercial description. This same subscription model is found on other products in the EcoFlow Stream range, without this being systematically highlighted at the point of purchase.
A zero-injection mode that can fail
Anti-injection control, meant to prevent any unwanted feed-back into the grid using a compatible smart meter, doesn't work reliably for everyone: this mode failed, in at least one reported case, even with a Shelly meter or the recommended EcoFlow smart meter. This is a specific technical point to check before buying for anyone relying on this function, particularly under a contract with a no-reinjection obligation.
The IP67 rating, solid over the short term, not yet proven over time
The advertised IP67 rating, clearly above the more common IP65 on this type of device, withstands a full 30-minute immersion followed by immediate restart with no degradation. The product remains, however, too recent, launched mid-2025, to have feedback covering multiple seasons of continuous outdoor exposure. An isolated case of intermittent cutout on one module over several weeks has been reported, with no cause identified and no established link to the seal.
Installation and compliance in France
Installation doesn't require an electrician: mount the bracket, connect the panels via the MC4 connectors, and plug the supplied mains cable into a household outlet, with commissioning through the app taking about fifteen minutes.
For this specific case, a microinverter alone with no battery capped at 800 W, the French regulatory situation is clear: the declaration to Enedis (self-consumption agreement) remains necessary regardless of power output, but no Consuel certificate is required as long as the connection is made through a simple outlet, the Consuel intervention threshold being set at 3 kWp.
Against the Hoymiles HMS-800W, the market reference
Against the Hoymiles HMS-800W, already featured in our comparison, the Stream shows a slightly lower peak efficiency, around 95% versus 97%, and a shorter warranty, ten years versus twelve, for an estimated annual production gap judged modest in everyday use. The Stream stands out, however, for its EcoFlow software ecosystem and the option to add a storage battery, Stream AC, Pro, or Ultra, to grow into a complete system, an option the Hoymiles alone doesn't offer.
The actual price
The listed price is 139 € on promotion, against 209 € outside of promotions, a gap confirmed on both Amazon.fr and the manufacturer's official site. That's a competitive rate for entering balcony solar, before any optional storage battery is added.
