Large-scale Solar

Suntrace focuses on large-scale solar technologies and demand matching energy supply concepts

Smooth transition from conventional to renewable energy supply is important. With growing penetration of renewable energy, fluctuation of Wind and PV can impose challenges on exisiting electric grids.

Suntrace develops specific solutions to match specific project requirements. This includes the design of complete energy concepts tailored to the energy demand of the off-taker, be it on-grid or off-grid, industry or public. Energy storage and hybrid elements can enhance solar projects to provide firm and dispatchable power. These projects can match demand, and thus subsitute conventional capacity.

Suntrace covers the following elements for dispatchable solar energy:

Photovoltaic (PV) 

PV is the most mature solar technology, dominating in terms of installed capacity. Cost per MW for modules and associated systems (BOS) dropped drastically during the last years, allowing already a grid parity (at consumer price level) in several markets.

Different technologies and system solutions are competing, e.g.

  • Technology: crystalline silicon vs. thin-film modules

  • Installation: fixed vs. 1-axis or 2-axis tracking, optimised layout of plant

  • Distributed (few kW) vs. large-scale centralised concepts (>hundred MW)

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Concentrating Solar Power (CSP)

CSP or solar thermal electricity (STE) plants are an alternative technology for producing electricity or process heat from solar. However CSP is less mature in terms of proven systems and established markets. Until 2009 CSP was more competitive in terms of price per electricity produced. The decline in PV prices has reversed the competitiveness between the two technologies.

In CSP, various technologies are available, e.g.

  • Parabolic trough
  • Linear Fresnel
  • Central receiver (Solar tower)
  • Solar Dish (e.g. Dish Stirling)
  • Heat transfer fluid (HTF): Thermal oil vs. direct steam generation vs. molten salt vs. heated air (pressurized/ambient condition)
  • Small scale (1-5 MW) vs. large scale (50-250 MW)
  • Supply: electricity and/or process heat; combined heat and power (CHP)
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Energy Storage

Dispatchability / firm capacity generation is a growing requirement to renewable energy systems. With growing penetration of fluctuating renewable energies such as wind or PV, electricity grids are increasingly struggling to balance the electric grid, as back-up generation has to be prepared but predictability of required dispatch for these plants becomes more and more difficult.

Basically, the decoupling of solar resource availability and energy delivery to the consumer/grid is required. Several technical solutions enable solar power plants to enhance the generation profile beyond the direct conversion of solar irradiation into electricity, such as energy storage and hybridization with alternative generation systems.

Energy Storage - application of energy storage solutions allow shifting of solar energy from sun-peak to consumer-peak times, or at least provide a firm capacity over a certain time period (up to 24/7 base load supply).

  • Electric storage (e.g. batteries) offer distributed and large-scale solutions, however at a significant price

  • Pump storage / Hydro systems are assumed the most efficient storage system, however are to be seen as a separate plant with pump and water turbine generator set, also limited to locations with available water and matching topography, both usually scarce in desert regions where solar resource is abundant

  • Thermal energy storage (TES) requires thermal processes, and thus for large scale solar only CSP technologies can include this option, as the heat generated in the solar field could be stored. Applicability and efficiency depends on type of technology and HTF

  • Chemical storage solutions are being discussed, such as conversion of excess electricity into methane (CH4), which could be stored or fed into the existing gas-grid, or also production of liquid hydrogen (H2)

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Hybrid solutions

either with bio-fuels  or fossil energy sources - can enhance the generation profile of a plant according to the demand profile from the grid operator or a captive consumer. Several technical options exist ranging from a small solar contribution (e.g. ISCC) to a dominant solar share, which could either leverage the cost of energy for the customer or simply allow the secure generation of energy (heat & electricity) when demanded. Hybrid solutions can integrate energy storage if commercially viable.

  • Diesel Generator for back-up power generation for hours with insufficient solar irradiation. Solar (PV, and also CSP) can already be competitive with diesel generated electricity, so that a substitution of fuel consumption is the most simple approach to hybridize existing diesel based power generation

  • Fossil power plants - gas fired (ISCC) and coal fired (steam augmentation) - could be enhanced or retrofitted with solar heat generation (CSP), with solar steam integrated into the power plant process. Solutions are tailor made, and thus require a detailed assessment of boundary conditions and requirements.

  • Fuel fired back-up thermal energy systems can range from small capacity (e.g. HTF heaters for freeze protection) to a full back-up capacity enabling to continue full load at non-solar hours (e.g. redundant fuel fired steam generator)

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