Introduction to solar cells – a literature review

Solar power is the fastest growing energy technology in the world, and investment in solar photovoltaics (PV) currently surpasses investments in all other electricity generating technologies combined. This report is a literature review of the current PV technology.
Solar cells utilize the photovoltaic effect, which is the process where materials absorb light and convert this energy directly to electricity. Crystalline silicon (c-Si) is the most commonly used material for solar cells. There are four key cell configurations: passivated emitter rear contact (PERC), interdigitated back contact (IBC), tunneling oxide passivated contact (TOPCon), and heterojunction with intrinsic thin layer (HIT, also known as silicon heterojunction: SHJ). After dominating the market for two decades, PERC technology is now being phased out due to its lower efficiency compared to newer technologies. TOPCon, with a module efficiency of 23.2%, is currently the dominant solar cell technology. However, IBC is the most efficient c-Si technology, achieving module efficiencies of up to 23.8%.
Higher efficiencies can be achieved using gallium arsenide (GaAs). This material is typically used in thin-film panels and has a record efficiency of 32.7%. GaAs is expensive to manufacture and is therefore mostly used in high-efficiency cells for spacecrafts and satellites. It is also well-suited for aerospace and defense, however. High-altitude long-endurance unmanned aerial vehicles (UAVs) powered by GaAs modules can stay airborne for months.
It is possible to exceed the efficiency of GaAs cells with tandem cell technology – multiple cells stacked to absorb a larger portion of the solar spectrum. This is regarded as a disruptive technology, and its theoretical efficiency limit is at 45%. Tandem cells are expected to reach the market in 2027.
Organic solar cells are another promising technology at the pre-commercialization stage, offering advantages such as low-cost, a small carbon footprint, flexibility, low weight, color tunability and semi-transparency. These properties make the technology highly attractive for military applications.
PV systems can be deployed in a variety of configurations to optimize land use. Emerging approaches such as agrivoltaics, floating PV, vertical PV and building-integrated PV (BIPV) are gaining traction. Additional developments include grid-supporting PV plants and hybrid systems that combine solar and wind power. In a military context, PV offers opportunities to enhance base resilience and operational readiness, while providing flexible and portable power solutions that reduce fuel dependency.
Despite the decreasing cost of PV panels, Norway has been slow to adopt this technology compared to the rest of Europe. When paired with a battery energy storage system (BESS), PV can reduce dependence on grid electricity, enhance resilience during power disruptions, and support self-consumption for much of the year. The findings in this report highlight the significant potential of solar power, and the Norwegian Armed Forces should further explore its integration, in collaboration with FFI’s Power Supply Group.