DIRIS DC from Digiware:

• DIRIS Digiware, also known as the multi-circuit power monitoring device, is the finest choice for metering usage.
• Monitoring and measuring the quality of electrical energy used in commercial and industrial environments.
• With the DIRIS Digiware U-31/32dc module, the DC voltage of the entire system is measured.
• It can measure up to 180 VDC when connected directly, so it can work with nominal voltages that are usually 24 or 48 VDC.