WHAT TECHNOLOGIES ARE CURRENTLY IN PLACE FOR SOLAR ENERGY?
There are two main types of solar energy technologies: 1) photovoltaic (PV), and 2) concentrating solar-thermal power (CSP). PV is utilized in panels. When the sun shines onto a solar panel, energy from the sunlight is absorbed by the cells in the panel, which creates an electric field across the layers and causes electricity to flow. CSP uses mirrors to reflect and concentrate sunlight onto receivers that collect solar energy and convert it to heat, which can then be used to produce electricity. CSP is used primarily in very large power plants and is not for residential use. 
Photovoltaic energy is the conversion of sunlight directly into electrical power. Commonly referred to as solar cells or PV cells, photovoltaic cells are non-mechanical devices that are most commonly made of different semiconductor materials. PV cells are connected together in chains to form larger units known as modules or panels in order to increase the power output of the cells. The panels are then connected to the electrical grid as part of the PV system.
PHOTOVOLTAIC KEY TECHNOLOGY AREAS
The PV portfolio of research and development includes the goal of reaching a levelized cost of energy of $0.03 per kilowatt-hour. Photovoltaic research efforts focus on the following key technology areas:
- Crystalline Silicon
- Cadmium Telluride (CdTe)
- Copper Indium Gallium Diselenide (CIGS)
- Earth-Abundant Materials
- Hybrid Organic-Inorganic Halide Perovskite
- Multijunction (III-V)
CONCENTRATING SOLAR-THERMAL POWER
CSP technologies concentrate sunlight through the use of mirrors onto a single point, a receiver, where it is collected and converted to heat. This heat, or thermal, energy is then used to produce electricity via a steam turbine or a heat engine that drives a generator. CSP technologies provide a renewable energy option for small-scale through utility-scale systems. Power tower systems use mirrors arranged around a central tower and Linear systems use rows of mirrors to concentrate sunlight onto parallel tube receivers.
CONCENTRATING SOLAR POWER KEY TECHNOLOGY AREAS
There are several CSP key technology areas:
- Linear Concentrating Systems (includes Parabolic Troughs and Linear Fresnel Reflectors)
- Solar Dish/Engine Systems
- Solar Power Towers
SETO is interested in the advancement of reliable, resilient, secure, and affordable integration of solar energy into the electric grid. These include innovations that advance a modernized grid which includes integrating solar and other energy generation while ensuring reliable power, cutting edge digital technologies to monitor and control components, and protection against physical or cyber risks. SETO funds opportunities for solar to supply electricity generation as well as provide grid services such as restarting segments of the distribution system if the grid goes down.
WHAT PROJECTS HAVE BEEN FUNDED BY THE DEPARTMENT OF ENERGY FOR SOLAR ENERGY TECHNOLOGIES?
The DOE’s Solar Energy Technologies Office (SETO) funds research and development in the areas of photovoltaics (PV), concentrating solar-thermal power (CSP), and systems integration to improve affordability, reliability, and domestic benefit of solar technologies. SETO supports research projects that drive down the costs of solar-generated electricity with improved efficiency and reliability. SETO’s goal is working toward a levelized cost of $0.02 per kilowatt-hour (kWh) for utility-scale solar PV, $0.04 per kWh for commercial PV, and $0.05 per kWh for residential rooftop PV. SETO funding goes towards technology approaches that show promise to achieve cost reductions and faster wide-scale deployment, with an aim of commercial success in the short term or 10-20 years.
Updated by Jennifer Ostromecki, November 2023