Before connecting a higher voltage array to a PWM controller, I would recommend reading this morningstar document: http://www.morningstarcorp.com/en/su...vPWM.01.EN.pdf
In the Array Sizing for PWM Regulators section my interrpretation of this note is recommending you should not do that:
NOTE: The Vmp of the array should be higher than, but as close to, the maximum battery voltage as possible. Vmp significantly higher than max battery voltage reduces efficiency and puts more stress on the switching components of the regulator.
Anyway, the document provides a lot of good information.