Energy efficiency of photovoltaic panels

Energy efficiency of photovoltaic panels: we talk about solar yield keeping in mind only the technologies currently on the market.

It is very difficult to talk aboutefficiency of photovoltaic panels. Equal tosolar radiationto which the cells are exposed and at constant temperature, the difference of yield (or efficiency) is given by the materials used for the production of solar cells.

Theyieldorefficiency of aphotovoltaic moduleis defined as the ratio expressed as a percentage between the energy captured and transformed into electricity, compared to the total energy incident on the surface of themodulesame. The energy efficiency of photovoltaic panels is a parameter that serves to establish the performance and quality of the module described.

L'efficiency of photovoltaic panels, also defined asyield, is proportional to the ratio ofwatts delivered and surface occupied other conditions being equal (irradiation, solar radiation, temperatures, sunlight spectrum, spectral response…). Having said that, it is natural to think that for the same energy produced aphotovoltaic panelmore efficient goes to occupy a smaller area.

Theyield of a photovoltaic panelit is closely related to the temperature and the materials used. For example, referring to the temperature of 25 ° C of a solar cell, depending on the materials used there will be different yields and different losses in relation to an increase in temperature.

ThePhotovoltaic cellsinCrystalline siliconshow a completeefficiencyat a temperature of 25 ° C but the efficiency drops by 0.45% for each degree centigrade of temperature increase.

ThePhotovoltaic cellsinMonocrystalline silicon, with good solar irradiation, they easily reach 70 ° C, too bad that at this temperature the loss ofyieldis about 25%.

ThePhotovoltaic cellsthose with multiple junctions are less affected by temperature (GaAs, Ge, InGaAs ...) which see losses of 0.05% for each degree centigrade of temperature increase.

For more information on the effect of temperature onyield of a photovoltaic system I refer you to the articles:

  • Photovoltaic NOCT: the yield of the system
  • Thermography on solar panels

Energy efficiency and photovoltaic panels, where are we?

It all depends on the economic investment that we can make for the realization of thesolar system. The more the yield increasessolar panelsand the more complex the production process becomes, as do the costs of materials and the final price.

Some concentrating collectors for terrestrial use, developed from the model aerospational, as well as some multiple junction cells, manage to return anominal yieldwhich even exceeds 40%! Unfortunately the values ​​ofenergy efficiencythat we find in commonly marketed solar panels are far less.

  • High efficiency heterojunction modules achieve ayielda record 25.6%.
  • Solar modules with monocrystalline silicon technology achieve efficiencies average of 21%.
  • Solar modules with polycrystalline silicon technology offer a yield average of 16.7%.
  • Older amorphous silicon modules offer ayieldaverage of 8.5%.

Among the excellences we point out some consumer technologies that reach ayieldequal to 25.6%. The leader in the production of solar panels is Panasonic which is establishing itself in the field of photovoltaic technology defined as "heterojunction". It is a hybrid solution that combines the best characteristics of the thin film (ability to produce energy without undergoing the rise in temperature) and the good conversion efficiency of solar modules with monocrystalline silicon technology. With photovoltaic technology aheterojunctionwe start talking about a hybrid photovoltaic cell, that is, it combines the advantages of different semiconductor materials. Photovoltaic panels with heterojunction modules will be marketed in Europe by the end of the first quarter of 2016 by Panasonic itself.

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