Yeah I see your point. My hope is because SLR can make a footprint in a specific community first, that the economy will come into being. We dont worry about who wants to buy Pounds, Euros, Dollars, becasue inside our bubble we all transact value with the same tokens. If we can create that similar industry bubble for Solarcoin, it might just work.
P.S. Its also important to note Bitcoin and therefore by extension SolarCoin, is cheaper, faster and more secure to use as a currency than Pounds, Euro, Dollars etc., this is why if a solar economy begins to emerge, participants would rather use SLR than their native fiat; SLR grants alone would not be enough to feed all participants in such an economy (unless users install more solar capacity) and will probably lead to currency demand.