Silicone gel technology
Specific PV applications
- Polar star
- Hybrid PV/T panels
- Solar concentrators
- Bifacial solar panels
- Solar street lamps
- High temperature PV panels
- Solar pumping systems
- Photovoltaic systems
DESERT STAR – Solar Photovoltaic panels for very hot areas
Silicone gel technology for lamination of high temperature (+110oC) PV panels TRAXLE:
The relative accessibility and ease of use EVA film allowed vast majority of companies to establish mass production of photovoltaic modules. However, since the late eighties, there were reports analyzing long-term experience in the natural-climatic testing and operation of modules with EVA films, in which it was noted darkening of EVA. It results in different degree of reduction of power, especially in systems working at high temperatures (above 85oC) with solar radiation concentrators.
This phenomenon, called in the publications "EVA darkening”, encouraged researchers working in this field, to study the problem of discoloration and the critical assessment of the possibility of further use of films of EVA.
Degradation and staining the encapsulant on the basis of EVA were observed mainly on the modules of the monocrystalline silicon (c-Si) with a glass protective coating, which operated in the hot (dry or wet) climate. For example, for modules installed in the Carrisa Plains (Central California), after 5 years of work there was a reduction of power for more than 45%. This phenomenon has been associated both with the darkening of EVA, as well as with other types of electrical degradation.
Fig. 1.1 EVA laminated PV panels in V-trough concentrator in Carrisa Plains just after installation
Fig. 1.2 EVA laminated PV panels in V-trough concentrator in Carrisa Plains after 6 months
In the VIESH research institute (Moscow, Russia) was developed the original manufacturing technology of vacuum glazing with a thermoplastic spacers around the perimeter, characterized in that the evacuated cavity is filled with an optically transparent medium in the form of liquid polysiloxane compound, laminable at room temperature on the mechanism of hydrosilylation in the low-modulus gel.
Recently VIESH in cooperation with Poulek Solar Company developed industrial scale technology suitable for multi MW PV panel production plants. The Poulek Solar Company is the only owner of the worldwide license of this technology.
|Long term operating temperature||-40 +80oC||-60 +250oC|
|UV radiation resistances||low||high|
|Operating lifetime||25 years||40 years|
|Energy consumption per panel||49 kWh||4.5 kWh|
|Transparency for solar radiation||8% (360nm)||90% (360nm)|
|Transparency for solar radiation||62% (400nm)||92% (400nm)|
|Transparency for solar radiation||91% (600-1000nm)||93% (600-1000nm)|
Comparison table of EVA & silicone gel encapsulant properties
Fig. 1.3 Silicone gel PV panel lamination unit – 1st generation (MK I)
New silicone gel PV panel lamination technology - Advantages:
- Inert material – Unlike EVA polymer encapsulant which can decompose, because of high temperature (80oC) or ultraviolet radiation, to acetic acid (causing degradation of solar cells), the silicone gel is inert in wide ranges of temperatures up to 250oC. Recent most advanced high efficiency solar cells are very sensitive to acetic acid coming from decomposed EVA
- Highly transparent material – The silicone gel is more transparent for solar radiation, compared to EVA. It results in about 1.5% higher conversion efficiency of PV panels laminated in Silicone gel compared to EVA. It is beginning of life value. The end of life (20 years) energy gain can be up to 15% (no yellowing/browning).
- Gel instead of solid state encapsulant – The silicone gel, unlike solid state EVA, enables mechanical stress relaxation during PV panel thermal cycling between day and night
The points a-c result in extended PV panel lifetime well over 30 years
Using the silicone gel technology the new TRAXLE PV panel was developed for long term operating temperature up to +110oC (standard EVA laminated panels +85oC only). It is very suitable for high temperature desert environment (PV panel temperatures up to +95oC).
The technological advantages of the TRAXLE products line can be summarized as follows:
- High temperature PV panels TRAXLE: Long term operating temperature up to +110oC (standard EVA laminated panels +85oC only). Based on silicone gel encapsulant TRAXLE panels outperform all EVA laminated panels. It is very suitable for high temperature desert environment (PV panel temperatures up to +95oC).
Licensing of the silicone gel lamination technology is possible. We will be pleased to deliver complete silicone gel lamination lines.
Data at Standard Test Condition (T=25oC AM=1.5 E=1000W/m2)
|1||Peak Power (Pm)||235W|
|2||Open Circuit Voltage (Voc)||37.0V|
|3||Short Circuit Current (Isc)||8.2A|
|4||Maximum Power Voltage (Vmp)||30.7V|
|5||Maximum Power Current (Imp)||7.7A|
|6||Temperature coefficient of the current||0.05%/oC|
|7||Temperature coefficient of the voltage||-0.31%/oC|
|8||Temperature coefficient of the power||-0.40%/oC|
|9||Maximum System Voltage||1.000V|
|14||J-box, cables & connectors||Tyco|
|15||Quantity & Dimension of Cell||60 pieces 156x156mm|
|16||Front Glass Type and Thickness||Tempered 3.2mm|
|17||Back Glass Type and Thickness||Tempered 3.2mm|
|Diameter of the hole||Φ9mm|
|20||3 By-pass diode||20 pieces cell parallel connection one diode|