Sol y Viento hybrid plant
A 110 MWh battery added to a working solar farm in southern Spain.
Curtailed solar cut by
61%
Size
55 MW, 110 MWh
Location
Valdehoya, Andalusia, Spain
My role
Commissioning lead
Team
8 commissioning staff, 2 vendors
Duration
13 months, 2019 to 2020
01
The situation
Sol y Viento is a 140 MW solar farm on a dry plain in Andalusia. Its grid connection can only export 100 MW. On bright days the owner had to throw away the difference, a loss known as curtailment. In 2019 that came to roughly a tenth of everything the panels could have produced.
Halberg won the contract to add a 55 MW, 110 MWh battery behind the same grid connection. It was the company’s second utility-scale battery and its first outside Sweden. The solar farm had to keep running throughout, because every day offline cost the owner money. We also had to work through a summer of 40 degree afternoons.
02
What I did
I led the commissioning team on site. We built and tested the battery as a separate island first, with its own temporary supply, so nothing we did could switch off the solar farm. The connection to the shared substation was made in a single planned night outage, when the panels were producing nothing anyway.
The hardest part was the control system. The battery and the solar inverters had to share one export limit without fighting each other. I wrote 38 test cases for that logic and ran them at low power for a week before going to full power. I also trained six local technicians, who took over operations when we left.
03
What changed
The battery now charges from solar power that would have been curtailed and sells it in the evening. In its first twelve months, curtailed energy fell by 61 percent compared with 2019. The solar farm lost no daytime production during the build, which was the owner's main condition when the contract was signed.
The site passed its grid compliance tests in October 2020, and the six technicians I trained still run it. Halberg used the island method again on its third site. It was the first project where I led the whole commissioning team, and the first where I handed over to people I had taught myself.
110 MWh
Battery capacity added
55 MW for two hours
61%
Less curtailed solar energy
First 12 months against 2019
0
Daytime hours of solar output lost
One planned night outage
