How Comet Solar improved ROI for customers with solar + storage + control technology

Comet Solar Log screenshot

Solar-Log Zero Grid-Export curtails inverter power to follow consumption.

Chris Mason, the owner of Comet Solar in Anguilla, has been installing and servicing solar PV plants in the Caribbean for almost 15 years. Installing solar plants in the Caribbean comes with some local utility regulatory challenges.

  1. The local utility companies do not allow excess energy to be exported to the grid.
  2. In fact, the utility meter will actually run in the same direction when you feed-in as it does when you consume grid power. This is called metering in absolute mode.
  3. If energy is being fed into the grid, the utility company will charge the plant owner by metering in absolute mode.

“In some cases, solar plant owners could actually end up with a higher electricity bill than what they had before,” Mason explained.

Comet’s solution

Location: Island Harbour, Anguilla
Nominal Power: 8kW
Inverter Type: SMA SB8000TL-US
Storage System: Sonnen ECO16, 16kW
Monitoring and Control: Solar-Log 1200, Solar-Log 2050 , Solar-Log WEB Enerest XL

One of Comet Solar’s areas of expertise is retrofitting existing solar plants with storage and control technology. In 2019 Comet Solar installed an 8-kW rooftop solar PV plant in Island Harbour, Anguilla. By installing a Sonnen storage system and using Solar-Log’s control technology, the plant owner is able to make use of the solar power produced while limiting the amount of power exported to the grid. They purchase less power from the utility company and avoid feed-in charges.

“The Sonnen system is AC coupled to an SMA SB8000 inverter,” Chris said. “Sonnen is a great battery solution to deal with larger loads because it is AC coupled, but it does not have a zero grid-export solution. This is where Solar-Log comes in.”

Comet Solar log design

Comet Solar needed to be able to monitor the power being produced and reduce the output of the inverter to prevent any export. Solar-Log can act as a bridge between the Sonnen battery and the inverter.

The Sonnen battery acts as a consumer. Once the battery is fully charged, and no longer “consuming” the Solar-Log will kick on the power control feature. The Solar-Log measures consumption and curtails inverter power. When production matches consumption, it means no excess power will be sent back to the grid.

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