You will see both materials being offered by solar tube manufactures. Polycarbonate is very strong and offers some advantages when particular specialist fire standards need to be met – specific commercial situations only (contact us for details). But polycarbonate has two disadvantages when compared to other materials; it has a relatively poor transparency rating and, rather alarming for a product designed for outdoor use, it goes cloudy and yellow when exposed to UV in as little as 12 months.
Acrylic, also known as Plexi-glass and PMMA, on the other hand has most efficient light transmittance factor being even better than glass. It’s also strong enough to withstand the rigours of whatever the weather, or a clumsy builder, can throw at it.
Read the acrylic vs polycarbonate summary of the BRE test