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Ready for the reserve market – Solax Reserve Market Batteries now available

We are introducing a great new product for single-family homes, business properties and housing companies that want to enter the reserve market: Solax reserve market batteries. The range includes 8, 12 and 15 kW inverters and suitable batteries that are already approved for the reserve market.

For single-family homes, a 12 kW or 15 kW inverter with a 12 kWh battery is suitable as a home battery. By combining 15 kW inverters, it is also possible to supply slightly larger sites such as housing associations and companies.

Solax is approved for the reserve market

Reserve market trading with Solax batteries began at the beginning of February 2025 when the entire Solax 6-15 kW product family was approved by Fngrid.

Checkwatt acts as the aggregator, taking 20% of the reserve market revenue. The rest is paid to the customer monthly.

For example, based on 2023 figures, one Solax with a discharge power of 12 kW would have generated €2,972.40 in revenue from the reserve market, which could be paid to the customer. Based on 2024 figures, the payment would have been even higher.

You can find more about the reserve market in our article .

In principle, Solax reserve market batteries work with Checkwatt specifically in the reserve market, but optimizing exchange electricity and maximizing the use of solar electricity are also part of the package. In practice, there are two options here.

If you have selected exchange-traded electricity from Checkwatt’s Energy in Balance service, the panels’ output is directed to the battery. The AI function, or smart control, automatically optimizes exchange-traded electricity and panel output when the customer has exchange-traded electricity.

If the selection is for a fixed electricity contract, the function is not possible. In this case, the following procedure is followed: When operating with photovoltaic power, the system uses photovoltaic power as normal for the building’s electricity consumption. Excess production is stored in batteries for later use when the reserve market requires a downward adjustment of the grid frequency.

Excess production is discharged into the grid when the reserve market requires an upward adjustment of the grid frequency = In this case, solar electricity generates reserve market income and the excess production selling price according to the customer’s electricity contract. Transmission fees and taxes on the purchase of electricity are also saved in this regard.

Works simultaneously as a solar inverter

The Solax reserve market battery inverter also functions as a solar inverter. This offers several advantages.

In locations where the grid company sets a maximum 17 kW limit on inverter power, for example, and where a 10 kW solar power system has already been installed, for example, it is now possible to install a reserve market battery by replacing the solar power system’s inverter with a Solax.
If you want to install solar panels at the same time, they can be installed without purchasing a separate inverter.
The target’s fuse size can be utilized to the maximum for reserve market use

Solax batteries can be installed outside

One of the great features of Solax reserve market batteries is that they can be installed outdoors without a separate outdoor installation cabinet. Outdoors, the battery operates down to -20 degrees, after which it goes into hibernation mode. When the temperature rises above -20 degrees, it starts working normally again. Installing the battery outdoors does not affect the battery’s warranties.

Two Solax X3 Hybrid inverters installed.

Checkwatt CM10

CheckWatt CM10 is an advanced control unit that allows you to join the reserve market. Through the CheckWatt portal, you can monitor the status of your battery in real time and view its performance in the reserve market.

During the installation phase, the CM10 is connected to the inverter via Modbus and to the local network via the LAN port. Each CM10 device has a unique serial number, which is required for registering the device in the CheckWatt system.

CheckWatt is a reserve market service provider approved by Fingrid, which enables customers to participate in the reserve market and reap the financial benefits it provides.

Solax X3-Hybrid-15.0-D hybrid inverter

High efficiency

150% panel power rating and up to 110% AC overpower output
High efficiency for charging and discharging, up to 97.5%
Global Maximum Power Point Tracking (GMPPT) for production efficiency

Economic

16A DC side current for a single line, support for high-performance panels
Up to 150% of the panel input power
Store excess production in the battery
Low starting voltage keeps the inverter on longer
Less loss between battery and inverter
Flexible battery operation according to electricity price

Intelligent

150% critical load for 10 s
Changeover time< 10ms
Quick update via USB port
Lithium-ion battery ready
Current transformer readiness, load response 0.3 s
Intelligent load management (e.g. heat pump)
On & Off grid parallel operation, up to 150 kW
5 operating modes, 2 charging times available
VPP readiness, an ancillary service for the electricity market
Three-phase unbalanced output. Maximum output power of 5 kW in single phase
Super-backup readiness, critical load without battery

Safe

IP65 protection class
Built-in surge protection SPD

Solax HV10230 T30, 3kWh – Triple Power 3.0 Battery

Features

Systematic planning and optimization – seamless connection with Solax hybrid inverter
Unique battery heating technology that enables operation in low temperatures with the Hybrid G4 inverter
Safe LiFePO battery, utilizing high-performance processors
Modular stacking, easy installation, sturdy floor mounting
Automatic power-up technology to prevent battery overdischarge
IP65, can be installed indoors or outdoors
Remote diagnostics, updates and troubleshooting
Several different network connections: RS485, CAN
Long-lasting, over 6000 charging cycles
Safety certificates TUV, CE, UN38.3