FAQ: Network Charges

• How has Modo mapped DNO region to TNUoS Generation Zone regions in the Run Library?
• Why are TNUoS rates £0 for transmission-connected systems?
• Do you consider Distribution Use of System charges in the revenue forecast?
• What impact do line losses have?

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How has Modo mapped DNO region to TNUoS Generation Zone regions in the Run Library?

In the run library, users can pick the distribution region of their run. DNO regions have a many-to-many relationship with generation zones, so we have used the following mapping for simplicity:

If you'd like to select the specific generation zone for your asset, soon you will be able to do so in our custom run flow.

Why are TNUoS rates £0 for transmission-connected systems?

TNUoS rates are split into fixed and flexible costs; and are different for distribution and transmission-connected assets. An overview of the TNUoS charges is given here.

We assume no site is importing during a triad - as this can be an expensive time to charge. Any optimizer should avoid charging during those periods or price the risk of a triad period into any contracts they secure that may require charging.

Those connected at the distribution level are liable to get TNUoS triad fees for exporting - and these are shown in the regions where the fees are non-zero.

Those connected at the transmission level are exposed to the Wider Generation Tariff, which can be positive or negative. This is a fixed cost - and so cannot be optimized around. Generally it is low as the Annual Load Factor for storage is low.

At the moment, we don't show fixed network tariffs in the forecast line items. So, like other fixed network fees (like standing charges, RO, FIT tariffs, etc), we do not show TNUoS rates for transmission-connected assets.

Do you consider Distribution Use of System charges in the revenue forecast?

We do not include Distribution Use of System (DUoS) charges in our revenue forecasts. This is because the majority of battery sites are connected at EHV on the distrbution networks. DUoS rates are very close to 0 for these sites.

We do not model fixed costs in our revenue forecast - like fixed DUoS or standing charges. Batteries are exempt from most of these costs.

If you have a LV or HV site, we are able to consider DUoS charges in a custom run. Please discuss this with your account manager and they'll be able to advise on the inputs required.

What impact do line losses have?

Transmission Loss Multipliers (TLMs) apply to transmission-connected assets.

Energy accounts are settled at the Notional Balancing Point (NBP). Energy is lost due to transmission losses from the point that it is generated to the Notional Balancing Point. For assets at lower voltages (such as those embedded in the distribution networks), the power has to travel through more of the network to get to the NBP - so the losses are higher.

They are regional (there are 14 zones corresponding to each Distribution Network or GSP group) and time-of-use dependent. There are two types of losses: Transmission Loss Multipliers (TLMs) and distribution level losses (D-loss). Typical values for these:

• TLMs ~ 1%
• D-Losses ~2%

They also depend on the voltage level of the asset in question. Usually, multipliers are higher overnight than during the peaks. They can be negative as well as positive. The TLM calculation attributes part of the transmission losses to generation and part to demand: there is a Generation/Demand split (currently, 45%).

Further explanation and example calculation for TLMs is given here.

What do Transmission Loss Multipliers mean for storage?

Transmission-connected assets will be subject to TLMs only and not D-Losses.

Most batteries connected at the distribution level will be connected at EHV - and the D-Losses will be minor (less than the 2% quoted above).

Below is an example calculation of TLMs for a charge and discharge action in the summer in Northern Scotland. We import 100MWh/88% (to account for battery efficiency) at 4 am when the energy rate is £10/MWh. We export 100MW at 5 pm at a rate of £100/MWh.

These example prices are lifted from the National Grid ESO TLM guidance document

Example of energy generation revenue at NBP

= Energy Tariff x (Metered Volume x TLM)
= Energy Tariff x Metered Volume x (1 +TLF + Gen Loss Adjustment)
= 100 x 100 x [1 + (-0.01471) + (–1 x 2% x 45%)]
= 100 x 100 x 0.97629
= £9,762.90

Example of energy demand cost at NBP

= Energy Tariff x (Metered Volume x TLM)
= Energy Tariff x Metered Volume x (1 +TLF + Demand Loss Adjustment)
= 10 x 113.6 x [1 + (-0.01471) + 1 x 2% x (1-45%)]
= 10 x 113.6 x 1.02571
= £1165.20

The Modo Forecast doesn't take into account Transmission Loss Multipliers.

Users should apply the relevant loss multiplier to their site to account for them.

TNUoS charges are calculated using metered volumes, not loss-adjusted volumes.

Using the above example, instead of

£100/MWh x 100MWh - £10/MWh x 113.6MWh = £8864 profit

We have

£9762.90 - £1165.20 = £8597.70 profit

I.e. a difference of around 3% uplift.