Conservatory roof and 'Solar Control Inserts'

We've just recently had a conservatory added to the house - a perfect job in every way. It has a polycarbonate roof, and we are looking at using 'polycool - Solar Control Inserts' to help control the temperature all year round.
The product looks good, but before I go ahead and buy, I'd be interested to hear from anybody who has had personal experience of the product, and how effective it proved to be.
Any pros and cons? Any alternatives?
Many thanks in advance,
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