My invoice is less favourable than calculated in the simulation. Why is this?

There could be several reasons for this:

1. Insufficient access power

Check whether the access power is sufficiently high, taking into account the additional power of the battery.

If this access power is insufficient, the grid operator will charge an excess tariff.

You can find the access power on your invoice, in the details section of the network costs. You need to divide the number in kW by the number of days in that month.

Adjusting the access capacity is a very important aspect of successful site delivery. This is also covered in detail in our training course on using the BESS simulation tool. It is up to the Yuso commercial partner to explain this clearly to the customer, but ultimately the end customer is responsible for adjusting their access capacity with the grid operator. This is also clearly stated in the steering agreement signed by the end customer.

2. Following the standby signal

The financial result of the control system is also highly dependent on how well the Yuso Certified controller follows the signals from Yuso. We often see that the standby signal in particular is not followed properly, and that self-supply is used instead. This will normally reduce the financial result of the control. You can check this by looking inside at the Volumes of energy charged and discharged on imbalance.

3. Imbalance prices

The financial result of the control also depends on (extreme) imbalance prices. Less volatility on the imbalance market will result in less throughput through the BESS, which also means less revenue.

Periods with a lot of sun and wind are good for volatility in the imbalance market. A lot of sun and wind cause a greater deviation between actual production and predicted production. This has an impact on the imbalance of the grid. In the last months of 2024, there were several periods of dark doldrums. During a dunkelflaute, when there is little sun and wind, imbalance prices will therefore also be less extreme.

With the introduction of Picasso, there have also been changes in the market in this area. Because cross-border cooperation is now in place to eliminate grid imbalance, we are seeing fewer extreme prices.

At present, it is difficult to estimate the lasting impact of Picasso due to the combination with dark doldrums, but we are of course monitoring this very closely.