Solar projects face extreme curtailment under ‘bizarre’ connection offers

Solar and battery projects have been warned they face extreme levels of curtailment under “bizarre” connections offers made as part of an industry programme to cut grid wait times.

Chris Hewett, chief executive of Solar Energy UK, suggested that network companies are attempting to use the programme to “make it look like they are doing something while they still fail to invest in vital upgrades.”

With wait times growing to well over a decade in some cases, network operators have announced a series of measures to reform the way they offer and then manage connections to the power grid. These include the Technical Limits programme, which was announced by the Energy Networks Association in April last year as part of a three-step plan to speed up connections.

The programme, which is now being rolled out by the Electricity System Operator (ESO) and distribution network operators (DNOs), concerns situations in which connections to distribution networks are being held up by a lack of capacity at the transmission level.

In such instances, the ESO will provide DNOs with technical limits for power flows through the relevant grid supply points (GSP) connecting distribution networks to the transmission network.

DNOs can then offer customers earlier non-firm connections whilst they await the completion of the grid reinforcements ultimately needed to accommodate firm connections.

In meantime, DNOs will monitor power flows across the relevant GSPs and curtail the output of customers when necessary to stick within the corresponding limits provided by the ESO. Customers will be curtailed on a last in, first out (LIFO) basis.

However, Solar Energy UK said many solar and battery project have received “bizarre” connection offers, which indicate they would be unable to export power to grid for most of the time. It cited the consultancy Novogrid, which said it had seen 50 such offers over the past three months, all forecasting curtailment levels of more than 90%.

Solar Energy UK said the lowest curtailment level it had seen forecast as part of an offer was 63%, with the connection only being brought forward by a year. The trade body said it had even heard rumours of one solar project being told it would only be able to export power to the grid at night.

It likewise highlighted the example of a 49.9MW solar project in the Midlands, which was reportedly told by National Grid Electricity Distribution it would likely be completely curtailed at all times of day and throughout the year.

The offer was posted on LinkedIn (see below) by Keir Spiller, managing director of Certus Utility Consulting, who wrote: “But the good news is that they could connect now in 2028 instead of 2032! Who has decided that connections with these levels of curtailment should even be offered as solutions? It feels like serious box ticking by all transmission and distribution operators with zero regards for what is actually achievable.”

“You couldn’t make it up,” lamented Hewett. “The idea of offering a grid connection that you can’t use and calling that some sort of success is absurd. It is like being told you can open a shop on the High Street, as long as you keep the doors locked.

“This is bizarre behaviour, and an apparent attempt by the DNOs to make it look like they are doing something while they still fail to invest in vital upgrades.”

Solar Energy UK said the “root cause” of the problem is “preposterous assumptions” about how solar and battery projects will operate. It said co-located solar farms and battery systems have been commonly assumed to both export at full capacity at the same time, when in reality the solar farm would charge the storage system during the day to then sell the power once the sun goes down.

Paul Manning, co-chief Executive of NovoGrid, said these flawed assumptions are in turn the result of an “utter lack” capable staff to conduct power flow analysis. Rather than using dedicated modelling software, Manning claimed network operators have resorted to using a far more simplistic calculation system in Microsoft Excel.

He said this system produces extremely cautious results to avoid potential liabilities if curtailment levels turn out to be greater than forecast: “This is why they use such ultra-conservative assumptions to ensure that they can never be wrong.”

Manning said although the pay is good – more than £70,000 per year for someone with limited experience – the high pressure work environment of network modellers means they often end up leaving DNOs for consultancy roles after just a few years. He said there is also global shortage of skilled workers, meaning they cannot be easily attracted from abroad.

Solar Energy UK said the structural nature of this problem means “solutions are limited, beyond actively seeking to recruit and train new engineers.” It said getting this to happen may require changes to DNOs’ price controls.

The trade association also noted that some DNOs are making data publicly available so developers can calculate the risks of curtailment more accurately themselves. It said other DNOs should be forced to do the same.

Solar Energy UK put out the warning ahead of Hewett’s appearance before the Environmental Audit Committee on Wednesday afternoon (7 February) where he also raised the issue with MPs.

A spokesperson for the Energy Networks Association said: “Electricity networks are spending and investing around £30bn over this price control period and undertaking the biggest programme of reforms in the history of the grid. We unlocked 50GW of capacity for customers last year, thanks to the urgent reforms we’re undertaking. Our members are continuing to work with customers to improve and accelerate connections in a way which maximises capacity and supports their projects.”