More like Silicon provides spinach a power boost, and spinach hurt's silicon's efficiency.
I don't mean to sound jaded, but there are a few very obvious issues with this that are going to have a hard time competing with current PV cells.
1) space used is a premium. At best, a roof of a traditional home is going to have 50% of southern exposure, and with many houses there is much less southern surface area. Getting into urban areas it is much worse; you have a flat roof which gives you 100% square footage to work with, but there are often many more families to provide for in that same area. These voltages with this kind of surface areas are not useful for mass application.
2) In nature you do get near 100% efficiency, as in use of power received, but that power is not stored or transferred in the form of electrical energy like the article states; It is stored in the form of proteins which are used very directly as fuel for the rest of the plant. When we have to convert to electricity, store it in batteries, and then convert to AC electricity, we loose a ton of that potential energy, but then again what else are we going to do? I mean, my heater/AC/lights/computer run on electricity, not proteins. If plants had to convert to and use electrical energy like we use for power they would not be anywhere near 100% either.
3) I am not going purchase new cells, and go on my roof, or hire someone to go on my roof every few years, much less months or weeks. Current PV cells last about 15 years, and from what I am reading some of the ones coming down the pipe will be good for 20-25 years (which is awesome because you can replace both the roof and cells on the same time table). Current cells pay themselves off in ~5-7 years, which means that soon you could be getting ~18-20 years of 'free' power from them, with very little maintenance on the cells (the batteries are obviously another matter). These organic cells would have to be extremely cheap and easily replaceable to justify frequent replacement costs. The lower up-front costs would be appealing, but roof work is scary, and dangerous, and priced appropriately.