Energy Storage Comparison: Hoymiles MS-A2 versus Marstek Venus C

Info: This article will be gradually enriched with additional information. The conclusion refers to the current state of knowledge of the characteristics compiled in the article.

The top models among AC-coupled storage systems: The Hoymiles MS-A2* and the Marstek Venus C*. Both storage systems can be excellently integrated into an existing balcony power plant. In this article, you’ll learn what distinguishes them and where their strengths lie.

Key Specifications: Hoymiles MS-A2 and Marstek Venus C

Even more characteristics and comparison with many other storage systems can be found in the comprehensive 📑 Balcony Power Plant Storage Comparison (in German) as PDF right here on the blog.

Comparison: Hoymiles MS-A2 and Marstek Venus C

Both models are AC-coupled PV storage systems. This means they can be connected directly to a power outlet. This allows you to set them up in seconds and easily integrate them into an existing balcony power plant. The Hoymiles MS-A2 can be plugged into either any power outlet or between the inverter and feed-in socket. The Marstek Venus-C, on the other hand, is connected to any power outlet. Both storage systems can use the Shelly Pro 3EM* as a smart meter, which makes it possible to control power output. Those who have their electricity meter within WiFi range can alternatively use an IR reading head like the EcoTracker* to control the storage systems. The two models apparently have much in common - the differences lie in the details.

More is More: Expandability

Both the Hoymiles MS-A2 and the Marstek Venus C can be supplemented by at least one additional unit. With Hoymiles, this works well according to user reports - however, the Marstek models still have difficulties with this (see PV-Forum: “Connecting 2 Marstek Venus E”). To couple more than two Marstek storage units, a Smart Box is required (according to the manufacturer), but this is not available anywhere.

Hoymiles MS-A2 Advantage

Two Hoymiles storage units can be coupled without problems and operated grid-tied. An update that should make it possible to operate three storage units simultaneously is already on the way. You can follow this feature and information about all Hoymiles MS-A2 updates on the PVExpress24 blog.

Off-Grid Functions

Both storage systems are off-grid capable. The Hoymiles MS-A2 delivers a maximum of 1200W (briefly) AC and 1000W continuously AC. The Hoymiles can pass through excess power from the connected PV inverter and thus achieves a maximum feed-in power of 1800W in off-grid mode (if you know more about this, please share your experience with me on X @bitlagerpro). As of July 2025, off-grid power supply with the Hoymiles works with only one device. The Marstek Venus C model is somewhat stronger here - it can deliver 2500W AC briefly and 2500W AC continuously. Another advantage of the Marstek is its larger capacity, which allows you to bridge longer dry spells. Additionally, a UPS mode can be set in the Marstek app, which supplies connected devices with power after 10ms during a power outage. According to some reports, the Marstek can also be charged via an inverter in off-grid mode when connected to the storage system through a power strip - but I cannot confirm this 100% yet (if you know more about this, please share your experience with me on X @bitlagerpro).

Marstek Venus C Advantage

The Marstek Venus C has higher output power and lasts longer due to its larger capacity. Emergency power supply can be activated in the app (The off-grid mode of the Hoymiles must be activated by pressing the button on the storage unit twice). Since both models can (apparently) be charged via inverter (+PV) in off-grid mode, both models receive a plus point for this. Since the Hoymiles can only be operated in off-grid mode with one device, even though coupling two devices works well, the point for off-grid mode goes to the Marstek due to (charging power), feed-in power, and capacity.

Conclusion

Not without reason, the Hoymiles MS-A2 and the Marstek Venus C are among the very popular AC storage models. Both have also approached each other in price, making the decision in favor of one of the two models very difficult. As of today (July 2025), I personally tend toward the Hoymiles MS-A2, even though the feed-in power and capacity are somewhat lower than the Marstek Venus C. For me, the Hoymiles is the more coherent package. Coupling two devices works, charging in off-grid mode via inverter and photovoltaics is possible, and reading via MQTT works with the Hoymiles.

Who is the Hoymiles MS-A2 suitable for?

If a feed-in power of up to 1200W and a capacity of 2.24kWh are sufficient for you, you want to expand your storage with an additional device in the future, and you want to read out the storage via MQTT, then the Hoymiles MS-A2* is the right storage system for you.

If you’re from near Königswinter, Germany, and would like to test the Hoymiles MS-A2 for 14 days without obligation, then feel free to check out PVExpress24.

Who is the Marstek Venus C suitable for?

If AC charging/discharging power and a capacity of 2.56kWh are important to you, you’re satisfied with just one device for now, you need the UPS function, and you’re looking for a storage system that should be charged/discharged based on dynamic electricity prices, then the Marstek Venus C* is the right storage system for you.

Nothing suitable for you?

If none of these storage systems appeal to you, then feel free to check out the 📑 comprehensive Balcony Power Plant Storage Comparison (in German)(PDF) - maybe you’ll find a suitable storage system for your balcony power plant there.

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