£23 ≈ US$38. At 18W that's US$2.11 per watt. That is indeed about half the price of silicon solar panels last I checked. I have no knowledge of these properties of melanin, so I don't know if this is a hoax.
I believe the ultimate ideal for this would be to make the hair easily replaceable by a person. Quite literally grow your hair X inches long, cut, hold out straight and clip into place. This is likely to be sold out in poorer countries where people haven't handled technology and need a simple way to maintain it. However the countries that would typically require this are somewhat blessed by the near perfect black of their hair, because blond hair has little to no melanin and would be useless, even brown hair would reduce efficiency greatly.
One man's religion is another man's superstition, I guess! And shaving off the hair is pretty harmless, as "superstitions" go -I mean, I got a lot of friends pretty non-superstitious types who shave off their hair here in the valley.
That price is the prototype price. It is pretty safe to assume this would be even cheaper when mass produced.
As for mass production: it also takes advantage of economies of scale (price goes way down), automation (price goes down), and "side channel" revenue streams -- open your own barber shops/salons and charge half of what others charge.
Wonder how long the hair lasts. If you continually have to rethread your panels, valve-style...