Quick answer
GridVolt forecasts what the site’s half-hourly meter would have shown if no trading instruction had been sent. That forecast is the baseline. After a trade, GridVolt compares it with the actual meter reading, and the difference can be the traded amount when the change came from the trading instruction.
GridVolt uses the submitted expected volumes method. In plain terms, GridVolt sends Elexon a forecast of what the site’s half-hourly grid meter would show if the battery did not take a trading instruction. That forecast becomes the baseline. If GridVolt then sends a different charge or discharge command for a trade, the trading calculation compares that forecast with the actual half-hourly meter reading.
There are several possible baseline methods, but GridVolt uses submitted expected volumes because commercial site load and solar output can change from day to day. It lets GridVolt use the latest site load, solar forecast and battery plan, rather than relying on a fixed historic average that may not reflect what is happening that day.
What GridVolt forecasts
GridVolt forecasts site demand and solar generation for the next 48 hours. It then works out the charge and discharge schedule it would use if the battery were only serving the site, without taking part in a trade.
That non-trading battery schedule may include:
- Charging from spare solar and using it later
- Charging when electricity is cheaper
- Discharging into the building to reduce site import
- Keeping an agreed reserve
- Staying inside import and export limits
From that forecast, GridVolt can calculate the half-hourly meter reading expected without trading. If GridVolt then sends the battery a different charge or discharge command for a wholesale trade, the traded amount is the difference between what the meter was expected to show and what the meter actually shows.
For example, if the battery was expected to charge during a half-hour, GridVolt may pause or delay that charge. The site then imports less electricity during that half-hour than the baseline expected, and that difference can form the traded response.
Why this matters for commercial sites
Commercial sites do not use power in the same way every day. A hotel, farm, warehouse or care home may have different loads by season, occupancy, production level or opening hours. Solar output also changes with the weather.
Because GridVolt submits a fresh forecast, the baseline can reflect the latest site load, solar forecast and battery plan. If solar generation is higher than expected, if the site load changes, or if the battery needs to behave differently for the customer, the baseline can be built around the latest forecast.
For the installer, the practical point is simple. Do not try to create the P415 trading baseline yourself in the proposal. Send GridVolt the half-hourly data, tariff, solar details, battery details and site constraints. GridVolt can then produce the no-trade forecast, calculate the change shown on the half-hourly meter after the trading instruction and keep the trading value separate from the customer’s normal bill savings.
Related questions
Does a GB commercial battery client have to switch electricity suppliers to trade?
What battery trading income can we put in a GB commercial proposal?
Does battery trading still pay if the customer is already on a wholesale-linked tariff like Agile?