Most of us have used or seen small solar home systems (SHS) providing power to rural communities in Fiji. These commonplace standalone systems come with a battery storage and sometimes include an inverter to provide AC electricity.
Being modular, there is no limit on the size of a photovoltaic (PV) plant and large strides are being made towards integrating PV into mainstream electricity networks.
This article focuses on grid connected PV systems (GCPV) which comprise PV panels and inverters but no batteries. These systems are directly connected to the utility grid. GCPV installations could be in the form of a large solar plant, a microgrid or smaller rooftop systems.
According to the recently launched REN21 Renewables Global Status Report (www.ren21.net/GSR-2015-Report-Full-report-EN) , 22.8 per cent of global electricity in 2015 was produced using renewable resources. Several studies have shown solar PV will play a major role in the coming years as the world moves towards a climate change resilient era which would be less dependent on fossil fuels.
Global PV capacity reached 177 GW in 2014 of which 44 GW was added in 2014 alone. There are approximately 70 PV plants worldwide with more than 50 MW capacity and there are many new initiatives to establish huge systems such as the proposed 750 MW plant in MP, India.
In the Pacific, the largest GCPV plant at the moment is the 2.2 MWp Faleata system in Samoa. Fiji has more than a megawatt of solar GCPV distributed over many sites from a 432.3 kWp rooftop system at the Radisson Blu Resort in Denaru to a ground-based 45 kWp system at the USP lower campus.
The PV technology is quite mature now and the prices of PV panels have fallen drastically in the last few years with installed PV system costs decreasing by 66 per cent between the years 2006 and 2013.
Despite the PV module cost reductions here are two major issues vis-Ã -vis wider expansion of solar PV systems — economic and technical.
Economic aspects
Payment for electricity generated PV is dependent on the national policies. There are two main mechanisms namely net metering and Feed-in-Tariff (FiT).
Net metering
Under this mechanism, a customer with a GCPV system pays the utility only for the net electricity used i.e. for the difference between the export and import. According to the REN21 report, net metering was being employed in 48 countries by 2014 end.
FiT
This is a special measure to promote renewable electricity generation. It involves installing two meters, one for import and the other for export. Exported electricity is given a different rate per kWh than that charged for the kWh imported. FiT was successful in the early phases of solar PV development to encourage investors through a price guarantee. FiT was one of the driving forces behind Germany’s leadership in solar PV expansion and is being implemented in about 100 countries globally.
There are two types of FiT mechanisms: Gross FiT, where all generation is paid at the special rate and Net FiT under which only the exported fraction of electricity is eligible for the FiT rate.
With the PV levelised cost of energy (LCOE) approaching grid-parity or even cheaper, net-metering is gaining more traction.
In Fiji, there is provision for net FiT but the rate per kWh for PV is still under discussion. It must be noted that the Fiji Commerce Commission has set a rate of 33.08 cents/kWh for the electricity supplied by independent power producers (IPPs).
Fiji also has a duty free facility for importing any renewable energy related equipment while the Reserve Bank of Fiji requires all commercial banks in Fiji to provide 2 per cent of their deposits and other liabilities in loans to renewable energy sector.
Another scheme available in Fiji is the Sunergise® option where the company designs, installs, operates and maintains the GCPV system installed at a customer site. There is no capital outlay and the customer pays a fixed rate for the electricity used.
Technical issues
Utilities are usually wary of electricity supplied by intermittent RE resources like wind and solar. Their main concerns are intermittent voltage, frequency fluctuations and the need to have a baseload power running in the background.
The first step into integrating more RE in the grid should be energy efficiency efforts to bring down the demand. Many studies have shown there are virtually no technical problems with integrating 15-20 per cent PV component in the existing grids and a great amount of R&D is being done to increase the share of intermittent resources in the electricity grids.
Viti Levu has an installed capacity of 262.94 MW and a peak demand of 155 MW. This would mean that about 25-30 MWp of PV can be integrated into the existing with minimal technical interventions. Since the PV output is variable depending on the weather conditions, it will be advisable to spread this capacity to all over Viti Levu with individual systems 10-15 km apart. The usually sunny conditions in the West part will adequately compensate for the frequent cloudy days in the East.
As the graph on the left shows, peak demand on Viti Levu (2007 figures) is around midday (solid line) and that’s when solar production peaks (dotted line). A total of 25 MWp appropriately distributed GCPV systems would significantly reduce the FEA net load during the day hours (dashed line). This would result in large fuel savings for FEA and associated reduction in Fiji’s carbon footprint. The private sector will be expected to play an important role in the development of these systems.
As we move towards higher PV component in the grid, storage and smart grid technologies will play important roles. These are exciting times for renewable electricity sector, especially solar PV.
Tesla’s Powerwall batteries have opened a new vista for rooftop solar systems. Other storage solutions like pumped-hydro have good potential in Fiji and should be investigated.
Thomas Edison said in 1931: “I’d put my money on the sun and solar energy, what a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.”
His words, like his many inventions, were so forward looking and it has taken us some time before grasping their true potential.
* Dr Atul Raturi is an Associate Professor of Physics at the University of the South Pacific. He is a regular contributor to the REN21 reports. The views expressed are his and not of this newspaper. He can be contacted at atul.raturi@usp.ac.fj.
