Photovoltaic withstood Caribbean hurricanes better than many buildings

25.10.2017
Antigua: While other buildings suffered severe damages, the rooftop solar installation remained unaffected from the hurricane. Photo: PV Energy
Antigua: While other buildings suffered severe damages, the rooftop solar installation remained unaffected from the hurricane. Photo: PV Energy

Photovoltaics systems withstood the hurricane in the Caribbean better than many buildings. Now they are an important element in rebuilding the infrastructure – and could provide Puerto Rico with the most modern electricity grid in the USA.

When hurricane Maria made landfall on the southeast coast of Puerto Rico on 20th September, the Humacao solar farm 6 km inland was one of the first areas of land to be exposed to the 250 kph winds. The first phase of the solar farm, which was finished at the end of 2016, managed to withstand the forces relatively well. But the solar modules of the northern expansion still under construction, consisting of 52 MW, were almost completely ripped from their mountings. On satellite photos by the National Oceanic and Atmospheric Administration (NOAA), taken one week after the storm, the boundaries of the two phases can clearly be seen; one half of the field shows rows of modules in the normal blueish grey of the solar modules, while the other half shows the rows almost entirely decimated.

The French company Reden Solar, then still acting as Fonroche Solair, had connected the 44 MW Humacao solar farm to the grid with its 64 ha area at the end of 2016. The system was fitted with Fonroche modules. Reden Solar has not wished to respond to several requests for details on the 2nd construction phase and the damage to the system.

There was also damage to other solar farms: the Ilumina solar farm in Guayama on the southern coast of Puerto Rico, installed by AES Solar from Boulder, CO, on 55 ha in 2012, was considered to be the beginning of the energy transformation there. The project was cofinanced with $30 million from Obama’s stimulus package. After analysing the satellite photos, it is estimated that a quarter of the modules from the 24 MW system were ripped from their mountings by the storm.

Hardly any damage to installations with adapted designs

Such damage seems to be the exception rather than the rule, however. The solar farm in Loiza, along a highway on the northern coast of the island, remained almost untouched. Loiza (27 MW) was constructed by the Spanish company TSK in 2013. TSK had taken extensive precautions against hurricanes up to category 5, as well as flooding. The solar modules and all the components, such as inverters and transformers, were mounted at least 2 metres above the ground on mountings designed by TSK itself. The TSK design withstood both the hurricane and the torrential rainfall well.

The largest solar farm in the Caribbean with its 58 MW, which was only finished in August 2016, also proved that photovoltaics can be made storm-proof. The farm lies in Isabela, on the northwest coast of the island. As part of the system is a 24 MW battery storage. The investment has been stated as being $160 million. Here, apart from occasionally torn away modules, almost no damage was caused. The farm was constructed by METKA-EGN from Greece, and continues to be run by the company.

In Puerto Rico the share of renewable energy, solar and wind, lies at just 2% so far. Solar power is above wind power here. The main share of electricity demand is met by diesel generators and gas-fired power plants, whereby the fossils fuels have to be imported, taking electricity prices (at 0.20 USD/kWh) to the high end for the USA. 

In Antigua & Barbuda, the government announced in May that it would create 30 MW of photovoltaics capacity over the next few years in various small and decentrally spread out solar farms. PV Energy, with its headquarters in London, is active in Antigua and has constructed 55 PV systems in the last few years, ranging in capacity from smaller rooftop installations to small solar farms (up to 4 MW). Among these is a 3 MW solar farm on the edge of V.C. Bird International Airport Antigua, which is equipped with 12,000 OurSun PV modules. After hurricanes Irma and Maria, Konstantin Wolf, CFO at The meeco Group/PV Energy Limited, reported that all 55 systems had withstood the storm “without damage”. In order to be able to stand up to hurricanes of category 4, the system designs underwent so-called Pull-Out-Tests to determine how deep the subframe had to be anchored in the ground. The tests showed, according to Wolf, that the structures for ground-mounted open-site systems have to be anchored over 2 m into the ground, and sometimes additional concreting is required too. Furthermore, solar modules with a frame thickness of 50 mm and strengthened glass have been used. The angle of the solar modules has also been adjusted so that they provide the wind with as little vulnerable surface area as possible.

Microgrids as a replacement for downed electricity grids

The robust construction and storm-hardiness of PV systems is worthless without a robust electricity grid, however. The electricity grid in Puerto Rico completely collapsed and consisted exclusively of overhead power lines. Even in the fourth week after the storm over 80 % of households were without electricity. Estimates say it could be 6-12 months before the whole country can be supplied again.

The question of what the grid should look like in Puerto Rico in the future is currently being discussed on all fronts, right up to an exchange on Twitter between Tesla CEO Elon Musk and Puerto Rico’s Governor, Ricardo Rosselló. Musk pointed to experience in building microgrids on islands in Hawaii, and said that such solutions were also an option for Puerto Rico. Governor Rossello announced the first successful talks as early as the weekend following the first Twitter contact. Instead of repairing the completely out-dated grid, a hurricane-proof and robust electricity grid should be created; of this much all in the debate are certain. The US Department of Energy and the US Department of the Environment also agreed this in public statements.

In five states, led by New York and California, the expansion and integration of Distributed Energy Resources (DER) and smart grid components, to set up a modern, robust electricity grid with a high share of renewable energies, is being discussed and tested with numerous pilot projects. Puerto Rico has the opportunity to fast-track its way to constructing the most modern electricity grid in the USA.

After the hurricane: no source of electricity is more quickly reavailable than solar power

Until then solar power will play an even more important role, as it has already shown that no source of electricity is more quickly available than the sun, especially in the Caribbean. Modules ranging from rooftop size to small power plants can be delivered and installed on site within days. A mobile set of solar modules called GREENS by UEC Electronics can be put up in just 15 minutes. The GREENS were developed for the U.S. Army and Marines, tested in the field, and have meanwhile been used hundreds of times. The 1,000 W set with battery storage can be transported by two people in several robust hard-shell cases, then set up and connected. Thousands of members of the National Guard and soldiers from the U.S. Marines are currently in Puerto Rico, distributing aid shipments and setting up emergency supplies for the population.

According to its own statements, Tesla supplied hundreds of Powerwall battery storage units to be connected up to existing PV roofs or combined with new PV to create a working system. In this way an expandable microgrid with a system on the roof of the fire station can include neighbouring houses, have further systems added to it and supply a growing community.

The large solar companies such as SunRun and SolarCity are present in the area, but so are various groups, including the Coastal Marine Resource Center, a group of solar engineers working with Walter Meyer, Professor of Architecture at the New School in New York. The center already helped with rebuilding the coastal communities using solar power in the wake of hurricane Sandy, which caused massive damage along the northern coast of the USA in 2012.

Just one day after Maria the group started its newest project, Resilient Power Puerto Rico, and flew out the first container filled with 17 tonnes of modules, batteries, cables, inverters, mountings and all manner of accessories to San Juan at the beginning of October. The aim is to create 20 so-called Solar Hubs in the first phase, from which the cut-off communities can be provided with solar powered community kitchens, medical centres, water treatment works and distribution centres. Up to 100 of these hubs are to be added by the end of the year and kept running by installers on site trained up by Resilient Power.

In Antigua & Barbuda, PV Energy has made two mobile sun2go XL solar systems with battery storage available to the search and rescue unit free of charge. As a further advantage of PV, Konstantin Wolf says that when there is infrastructure damage caused by natural disasters, decentrally set up solar systems can be replaced much faster than large centralised power plants and their relevant distribution infrastructure (electricity grids).

As a long-term target Resilient Power aims to bring enough resources to the island over the next four years to give each household the ability to power itself with solar electricity and be better able to defy hurricanes, the number of which will certainly not decrease in the future.

Anja Limperis

 

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