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Cotek SR1000T-248 Inverter Review

Front ViewRear ViewThis inverter was bought from ebay in June 2022 at a good price.

  • AC Input: 230V hard-wired
  • DC Input: 48V hard-wired
  • AC Output: hardwired & 2 x IEC C14
  • Maximum output: 1000W

Product Details & Manual

This was chosen so that there would be dual inputs, with an automatic transfer function to switch from DC to AC or vice-versa.

The device was configured for DC to be primary, with AC secondary. This was so solar power would be used until a low-voltage point, as which time it would switch back to AC power until the DC voltage rose past a certain point again.

Unfortunately, the selectable range of voltages when it swaps from DC back to AC is only 36 to 44V. This is usually quite low for a 48V Lithium system.

We would have preferred to change this "Under Voltage Protection" to a minimum of 48, but preferably 50V for our system, in order to allow other DC devices connected to the same solar system to remain powered overnight, without turning off the LiFePO4 battery.

There is an RS-232 serial interface which can be used to control the system and change settings, however, this did not come with the device (it was not new when bought), and finding a replacement has proven difficult - even the UK supplier of these devices could not sell us a replacement. If this could have been used, then hopefully arbitrary Automatic Transfer points could be selected.

Various other RS-232 cables have been tried with no success.

Another way to control the device is a "remote switch" option. Potentially a relay connected to another system would be able to control the Automatic Transfer, but such a device has not been sourced yet.

Unfortunately for now, the switch-over is a manual process, which is not ideal.


  • Price
  • 120V Type B and 24V versions are available
  • Dry Contacts available for starting generators
  • Nice form factor - 1U, half-depth
  • Reliable operation


  • Arbitrary switch-over voltage is not selectable
  • A new replacement RRP is ~£950+VAT