Alongside standalone battery revenues, our forecast now includes revenues for co-located sites.

How do we forecast co-located revenues?

Let's firstly consider the solar asset

Solar generation can be:

• Exported directly. We calculate exported solar revenues using the half-hourly wholesale power price.
• Used to charge up the battery. Rather than directly selling solar generation to make money, the battery can be charged up for free and discharged at a later more profitable time.

Operation depends on whether the site is AC or DC coupled.

If the site is AC-coupled, any solar generation exceeding the inverter power is clipped. It cannot be used for anything and is effectively wasted. This happens when the solar asset is oversized relative to the grid connection.

However, if it is DC-coupled, any solar generation exceeding the inverter power can still be used to charge up the battery. This means that DC-coupled sites minimize clipped or wasted solar power.

How about battery operation?

This also depends on whether the site is AC or DC coupled.

For AC-coupled sites the battery can operate independently to the solar asset, since it sits behind its own inverter. Therefore it can be optimized and dispatched in exactly the same way as for a standalone battery - as long as the sum of solar exported power and battery exported power does not exceed the grid connection.

For DC-coupled sites the battery and solar share an inverter. Since metering occurs at the shared connection, the battery cannot participate in frequency response services, as it is not possible to gain accurate meter readings for the battery alone. As a result, our co-located forecast only optimizes revenues in the wholesale day-ahead market for DC-coupled sites.

Finally, we do not differentiate between solar and battery revenues for co-located sites. This is because the operation of the two assets are intrinsically coupled and therefore, so are revenues. Instead our forecast provides total revenues for both the solar and battery combined.