The world’s critical solar markets remain China, the US, Europe, Japan and India, according to Howard Wenger, president of business units at SunPower, but with more countries joining the market, it will become increasingly international.
Despite the current minimal adoption of PV solar systems in Latin America, described by some as the new PV destination, Jeff Barnett, chief commercial officer for Yingli Solar Americas, predicts that annual installations will grow to 21GW by 2020. This forecast, however, will depend very much on long term sustainable developments in Mexico and Brazil, he emphasises, adding that the region is experiencing ‘normal growing pains’, particularly in the residential and small systems market, which will therefore require a slow, deliberate approach.
One specific aspect is a lack of consumer financing options, while Stefan Rinck, ceo of Germany’s Singulus Technologies, added that in Brazil there is also a regulation that specifies a minimum local content for solar farms, for example. He therefore suggested that growth will initially focus on smaller 300MW arrays, but this will require a reduction in costs for plants of this size. Shawn Qu, president and ceo of Canadian Solar, emphasised that his company is addressing this type of issue and is building solar plants in local markets.
While Barnett believes Mexico’s growth will be slow but predictable, the Brazilian market is ‘brimming but bureaucratic’. His forecast for installed capacity is a jump from an estimated 20MW in 2014 to 50MW in 2015.
According to Ricardo Rüther from the Universidade Federal de Santa Catarina in Brazil, the trend is to mix PV with other renewable energy installations in Brazil. ‘Solar and winds are complementary in many parts of Brazil,’ he noted, adding, however, that more recently, there has been increasing interest in floating PV systems, like those in Japan and Singapore. Brazil has around 100GW of hydroelectric power, with a total flooded area of some 40,000km2; with the addition of floating PV systems, this could potentially generate 5.7TW of electricity. Brazil as a whole needs to grow its diversified energy mix by over 5GW/year, he added.
For other countries in the region, such as Chile, Honduras, Uruguay, Ecuador and Peru, Barnett believes the focus will be on utility scale projects, but again, financing will be a key factor. His prediction for Chile is a jump from 493MW in 2014 to 1GW in 2015; however, one of the major energy consuming industries - mining - provides 36% extra load on the supply, but requires a consistent electricity supply. Currently, Barnett says there is 627MW of PV capacity in operation, with 1.3GW in construction and a massive 16GW in the pipeline. For Honduras, PV capacity is expected to grow from 2MW in 2014 to an estimated 310MW during 2015. Panama, which is also focusing on large commercial projects, is expected to grow from an estimated 3MW in 2014 to 62MW in 2015.
Turning to North America, the issue at the top of key concerns is US policy and the expiration, probably permanently, of the solar investment tax credit (ITC), considered to be the single most important government policy driving the deployment of solar systems across the US. The US installed base of solar assets grew beyond 20GW in the first quarter of 2015, and its focus is now believed by many to be shifting from the ‘gold rush’ stage to the development of strategies for the optimisation of these installed assets, but the removal of, or failure to extend, the ITC is forecast to severely constrain future solar development.
Although recognising that US policy is still a problem for the market, Al Bucknam, ceo of REC Solar in the US, said the industry needs to recognise that incentives can’t exist for ever but abrupt changes must be avoided. ‘There is a need to wean industry off incentives,’ he added. Canadian Solar’s Qu emphasised that despite the forecast US dip on the expiry of the ITC, global growth will continue,’ adding that global electricity consumption grows in line with GDP, but replacement generation is more likely to be renewable generation, and renewables surpassed conventional energy generation for the first time in 2014. ‘We are still in a very early stage of solar adoption, with low penetration,’ he noted.
Energy storage
According to Qu: ‘We have a responsibility to invest in its [energy storage] development, but he also noted that ‘in looking for suitable projects both technical and business models are still being developed’. Singulus Technologies’ Rick added that there is a need to be more critical about storage ‘not just from day to night’ but also in mobility applications and in the heating and cooling of buildings, which accounts for around 50% of energy consumed. This could involve using water heated by solar power: ‘We need to broaden our view in using PV to replace fossil fuels,’ he added.
SunPower’s Wenger emphasised the need to scale up battery production, something addressed by Tesla Motors’ co-founder and chief technical officer JB Straubel, in his presentation at the conference’s opening session, when he provided an introduction into Tesla Energy, the new arm of Tesla developing the Powerwall home battery and Powerpack commercial battery, and the construction of the company’s Gigafactory (see page 24).
Troy Miller, from the power quality division of S&V+C Electric, suggested that the batteries used to provide uninterrupted power supplies (UPS) in case of outages could also provide an alternative energy storage system when connected to a solar power system. Currently, he estimated that there is around 29GW of installed UPS systems using batteries that supply 5 minutes of power, which is equivalent to 2.3GW of stored energy. The use of Li-ion batteries could open up the use of dual purpose UPS/energy storage systems with the addition of appropriate control systems to shave off peaks in demand while reducing the costs involve by anything from 15 to 47% (C&I, 2015, 9, 31).
Sequoya Cross, co-owner and vp of sales and development at Backwoods Solar, said that battery technologies need to be chosen carefully, particularly because new battery technologies have no recycling experience, and disposal at end of life is a key issue.
Desalination as storage
Renewable energy shouldn’t be wasted if it is over-produced, according to Angelina Galiteva, a board member of California Independent System Operator (CAISO). Storage is one alternative, but another is desalination, which also addresses another key global challenge: the supply of potable water.
In the United Arab Emirates, for example, 99% of drinking water has to be ‘manufactured’ using desalination, according to Alexander Ritschel, senior manager at Masdar, who noted that solar desalination must ideally be sustainable and affordable with zero discharge. Masdar’s Renewable Energy Energy Seawater Desalination Program involves four partners, each providing a pilot plant at one location, using the same feed water, to evaluate the processes. The first pilot plant began operations in August 2015, and it is planned that the plants will operate for 18 months; Ritschel ‘hopes that all the pilots are successful and can be scaled up’.
Graham Beatty, from US-based Poseidon Water, said that with direct access to solar fields, desalination plants ‘can act like a battery’. His company is currently building solar powered desalination plants in Carlsbad and Huntingdon Beach, California. The key problem for further development is that solar farms are generally located away from the coast where desalination plants ideally need to be sited. Direct or grid connections are therefore essential, he said.
While reverse osmosis is currently the technology of choice, there are other alternatives. And as Ritschel noted, zero discharge is an important consideration, and only some processes, not for example, reverse osmosis, meet this criterion. Mahabala Adiga, president of Sun Desalination Systems and an affiliate of the University of Toledo, US, is working on a hybrid technology, based on thermal and electric conversion: PV mechanical vapour compression, another variant of an evaporation and condensation system, to meet this challenge.
While photovoltaic electrodialysis does offer good water recovery, in a modular format, and less stringent pretreatment, it does require the use of a membrane, which can be cleaned with a membrane life of up to five years. Photovoltaic membrane distillation can result in zero discharge; meanwhile, PV forward osmosis, while still requiring the use of a membrane, does not require the high pressure pumps needed for reverse osmosis. In addition, Adiga noted that the use of solar energy to raise the temperature of the feed water to 40-45°F can reduce the energy consumption in membrane systems.
Solar sites in San Francisco
The city of San Francisco has an estimated consumption of 1GW of electricity, supplied for the most part by hydroelectric power from the Hetch Hechy reservoir located some 200km away. The San Francisco Public Utilities Commission (SFPUC) is responsible for the provision of that electric power and also drinking water. The city’s municipal offices in total consume some 150MW, while largest single consumer of electricity is San Francisco International Airport at 35MW.
While there are many PV systems on residential buildings, a shortage of large-scale roof areas for bigger systems mean they are few and far between. San Francisco’s City Hall has just brought an 85kW rooftop PV system on stream to supply around 8% of the building’s demand. The building is designated as a national landmark, and local laws mean that the solar array must not be visible from street level.
The 30-year-old Open Hand Project, a San Franciscan charity delivering 250,000 meals on a daily basis to the needy, has almost filled its rooftop with solar PV and hot water systems. There is a 29kW system comprising 144 solar panels, which supply 15% of the total building demand, while the hot water system delivers water at up to 150°F on a sunny day, obviating the need for a hot water boiler.
Some energy is consumed in the project’s Room to Grow Greenhouse initiative, which is using Volksgarden rotating hydroponic systems, developed by Canada’s Omega Garden, each of which can grow 80 plants at once. One wheel, for example, produces sufficient basil for the pasta sauce used in 1400 meals. The plants are illuminated for some 16hr/day, enabling harvesting to take place six to seven weeks after planting the seeds. In addition to basil, lettuce, broccoli, and ‘micro greens’, such as lentil, arugula and mustard, are also grown using the Volksgardens.
On the waterfront, Pier 1, formerly a sugar import terminal completed in 1932, is now host to the San Francisco Harbour Authority, formerly housed in the adjacent Ferry Terminal. In 2012, as part of the upgrade before its occupation, a 200kW roof top PV system, comprising 840 panels, was installed, which has been delivering around 10% of the energy demand since August 2014.
All PV systems suffer to a greater or lesser degree from the accumulation of dust and dirt from the atmosphere, but for such a waterfront location, there is the added problem of contamination by seagulls!
Neil Eisberg is the editor of C&I
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