The invention relates to solar cells. More particularly, the invention relates to arrangements and methods to increase the efficiency of solar cells.The methods and arrangements of the invention allow to increase the efficiency of solar cells (11, 12, 13, 14) by
trapping photons into the
photovoltaic system by thermodynamic shielding based on at least one of the following: conductive shielding, radiative shielding (20, 21, 22, 400, 410, 411) and / or convective shielding. The best mode of the invention is considered to be a
tandem solar cell of Si (11) and InSb (12) enclosed in a vacuum container (200) to minimise convective
heat losses. Incident
sunlight is focused by a lens (320) to a diverging element (310) that disperses the
sunlight into the vacuum container (200) and on to the Si (11) layer that is facing the incident side of
sunlight. The vacuum container has reflective foil (400, 410, 411) on the inside to reflect retransmitted photons and thereby minimise radiative losses. InSb layer (12) is behind the Si layer (11). The semiconductors are suspended with
metal wires, minimising conductive
heat losses, which may include the
electrical contacts to the load (500) or the DC
inverter.