WEMO 2025 (complet) - Flipbook - Page 31
W E M O 202 5
O U T LO O K
• Grid balancing challenges with high shares of variable
renewable energy. Intermittent wind and solar generation
complicates supply predictability. For instance, solar power
peaks during daylight but drops at night, creating steep
ramping requirements, as seen in California’s “duck curve,”
223
where rapid dispatch of non-renewable resources is needed
to meet evening demand. As solar capacity grows, duck
curves are getting steeper and thus more di昀케cult to manage.
High renewable penetration levels can lead to overproduction
during peak generation, causing negative pricing and
curtailment, or shortages during low weather-related
generation, increasing outage risk. For example, U.S.
outages are already costing $150 billion annually224 .
Storing large-scale electricity remains expensive and
complex, with current technologies falling short. Lithiumion batteries, costing ~$115/kWh, typically store only a
few hours of grid supply. Pumped hydro storage, which
can provide up to 80% of global large-scale storage, is
limited in Western countries due to scarce suitable sites,
with most already developed. Emerging solutions like 昀氀ow
https://www.eia.gov/todayinenergy/detail.php?id=56880
https://greenridgesolar.com/price-perils-power-outages-battery-backup/#:~:text=Power%20
outages%20cost%20the%20U.S.,can%20be%20just%20as%20serious.
225
https://www.pv-magazine.com/2025/04/03/pv-curtailment-jumps-97-in-germany-in-2024/
226
https://www.renewableenergyworld.com/solar/negative-prices-in-caiso-what-ppa-buyersand-renewable-developers-need-to-know/#:~:text=There%20were%20~1%2C180%20hours%20
in,6%25%20of%20total%20hours).
The maximum share of intermittent renewables – such as
wind and solar – that can be accommodated by grids has to be
analyzed case by case. Indeed, it depends on grid infrastructure,
energy storage capacity, dispatchable generation sources
like hydroelectric or nuclear power, demand response
capabilities and advanced grid management technologies.
When the share of intermittent renewables exceeds the grid's
capacity, operational issues arise.
• Negative prices and curtailment occur when supply
exceeds demand, and producers, must then pay utilities or
consumers to take excess electricity to avoid curtailment
or grid instability. If negative prices persist or grid stability
is at risk, operators may curtail renewable output.
Episodes of negative electricity prices are becoming
increasingly common, particularly during periods of high
renewable generation and low demand. In 2024, in Germany,
223
224
https://www.spglobal.com/commodity-insights/en/news-research/latest-news/
electric-power/051325-solar-power-curtailments-spread-across-europe-in-early-may
227
negative prices occurred for 457 hours in 2024, up from 301
hours in 2023 with prices dropping as low as -€135/MWh
during peak wind and solar output, driven by the country’s
60% renewable energy share and constrained transmission to
the Southern industrial region (see above). Solar curtailment
increased by 97% driven by rapid growth in PV deployment
and unusually high solar radiation in the summer225
amounting to 3.5% of total renewable electricity generation.
Similarly, California’s CAISO market saw 1,180 hours of
negative electricity prices in 2024226 a signi昀椀cant increase
from 530 hours in 2023. These negative prices, driven
by solar oversupply (30% solar penetration) and grid
constraints led to around 2.2 million MWh of curtailed energy.
The weekend of May 10-11, 2025, saw some of the lowest
hourly prices ever recorded in Europe, with the Belgian
EPEX clearing at a record low of minus €462.33/MWh
on May 11. The same day, as much as 12 GW of solar
power was curtailed in Spain and 3.5 GW in France. 227
These cases illustrate how grids with limited ability to absorb
excess renewable energy – due to insu昀케cient storage,
outdated transmission, or slow demand response – face
economic ine昀케ciencies as these curtailment episodes reduce
electricity generators revenue.
WEMO 2025
batteries or gravity storage are not yet cost-competitive.
Additionally, the lack of inertia from inverter-based
renewables, unlike traditional rotating turbines, can
destabilize grid frequency and voltage integration. This trend
is expected to continue in the coming years with increased
renewables penetration and the closure of fossil-fuel plants.
30
technologies (see below) and AI-driven threat detection, like
Darktrace’s platform222, enhance resilience.
