RKS System of electric protection of solar batteries

At the beginning of 2017 the Russian Space Systems Holding (RKS, is a part of Roskosmos State corporation) completed creation of the upgraded system of electric protection for solar batteries of domestic production. Its application will allow to prolong significantly the term of operation of power sources of spacecrafts and will make the Russian solar batteries some of the most energy efficient in the world.

The basis of a system of protection of the solar battery is formed by diodes – the small devices installed on each photo-electric transformer (FEP) of which the solar battery consists. Diodes are one of crucial elements on which quality its energy efficiency and term of active existence depends.

FEP are located chains which call "string". When the solar battery in parts or in full gets to a shadow, FEP instead of giving of current on accumulators begin its consumption. That it did not occur, on each FEP the shunting diode, and on each "string" – the blocking diode is installed. The same way diodes operate when over time under the influence of the destabilizing space factors separate FEP or "string" fail – such elements are just cut, without affecting working FEP and other "thongs" respectively.

Head of section of fiziko-thermal processes of workshop of semiconductor products of RKS Alexey ANUROV: "RKS the first in Russia began to create nearly 20 years ago protective diodes and conducts their permanent upgrade – last year we completed development of new generation of these products. On the electric, mass and dimensional and nadezhnostny characteristics they are at the level of the best world analogs, and by a number of parameters are ahead of them. At the same time the cost of the Russian diodes is more than twice lower".

In construction of new diodes the patented technical solutions which significantly improve their utilization properties are used and increase reliability. So, use of specially developed multilayer dielectric isolation of a crystal allows the diode to maintain reverse voltage to 1.1 kV. Thanks to it the new generation of protective diodes can be used with the most effective of the existing FEP.

For reliability augmentation and service life of diodes in RKS created the new multilayer switching buses of diodes on the basis of molybdenum thanks to which diodes maintain more than 700 thermal shocks when temperature in several minutes changes more than on 300 Celsius degrees. Drawing a special protecting cover on all metal parts of the diode became one more innovation that prevents oxidation of a surface at contact with aggressive environments. It also allowed to increase the term of warehousing of the device from a year to five years.

Senior research associate of the sector of development of technologies of RKS Pavel DIDYK: "Thanks to the innovative design solutions the term of active existence of the solar battery of the spacecraft equipped with new diodes increased up to 15.5 years. 5 more years the diode can be stored on Earth. Thus, the general warranty service life of diodes of new generation makes 20.5 years. High reliability of the device is confirmed with independent resource tests during which diodes sustained more than seven thousand thermocycles".

In the USSR on solar batteries only the blocking diodes were used that led to fast degradation of solar batteries. In the 1990s during creation of domestic spacecrafts FEP of foreign production which were bought assembled with diodes were widely applied.

Leader of the development team of protective diodes Andrey BASOVSKY: "For the first time the Russian shunting diodes were created during joint work of specialists of RKS and JSC NPP Kvant during Creation of Solar Batteries for the International Space Station. Since Then RKS Remains the Key Supplier of Diodes for Solar Batteries of Domestic Production. the Operating Experience Showed that Application of Our System of Electric Protection Reduces Degradation of Solar Batteries Approximately by 10 Times.

The FEP standard size is 25 × 50 mm, and the area of solar batteries can reach 100 sq.m. therefore requirement of producers of solar batteries for diodes makes tens of thousands of pieces a year. The fulfilled group production technology allows RKS to produce more than 15 thousand diodes of new generation a year. Their deliveries are going to begin in 2017.

See Also

• Solar power in Russia