RELIABILITY AND DURABILITY IMPACT OF HIGH UV TRANSMISSION EVA FOR PV MODULES FOR THE EU PVSEC 2015

摘要

Recently, newly developed high UV light transmission EVA has been widely introduced in PV modules. It has been proven that this will increase the PV module power due to the better short wavelength response of solar cell, which will further reduce the cost per Watt of the PV module. However, the increased UV light irradiating the backsheet will cause increased backsheet yellowing and degradation. Hence most PV module manufacturers use a combined EVA, with high UV transmission EVA as front encapsulant and conventional UV cutoff EVA as the rear encapsulant. This work investigates the reliability and durability of high UV transmission EVA in PV modules. If conventional UV cut-off EVA is used as both front and rear encapsulants, the UV transmission rate and yellowness of the EVA increases after UV exposure, indicating degradation or aging of the EVA. The high UV EVA light transmission and clarity remained constant after 300kWh/m~2 UV exposure. The Yellowness index of UV sensitive backsheet showed that the high UV EVA caused the backsheet to degrade, while the conventional EVA and a combined EVA, with high UV EVA as the front and conventional EVA as the rear, did not produce any yellowing of the backsheet. This implies that the best combination is the use of the combined EVA to protect the sensitive backsheet. Suntech PV modules encapsulated with combined EVA have been subjected to UV extended testing up to 330kWh/m~2 UV exposure, with lower than 2.1% output power loss.