The hyphenation only matters to domainers, it seems. I have sold many hyphenated names for multiple thousands.
In terms of what the name is...it is THE category killer with a hyphen.
Someone would want this for that very reason....as a category killer, the name encompasses the entire industry, defines it perfectly, has broad reach and massive reach, has meaning to all interested in solar power, solar energy, alternative energy, and is a global product.
The hyphen would read as a space when placed in the google search bar. Yes, doubtful it would have much direct traffic...initially. With all the capabilities of bookmarking or historical searches, caches, etc., the hyphen is immaterial.
Yup, I bet a bunch of you have said it would lose traffic to the non-hyphenated. Well, guess what. There is not a non-hyphenated site. It says its coming soon but who knows how long that has been up. My belief is any traffic, ANY TRAFFIC, that the hypenated version gets is traffic the non-hyphenated is not getting, therefore the non-hyphenated is losing traffic to the hyphenated site.
In terms of site building, the hyphenated version would have to have dynamic SEO done to rank above the non-hyphenated version. The key will not only be SEO by very relevant and timely information. If I owned it, I would consider developing in a magazine like format and look to invite industry leaders or people in the know to be contributing writers.
It is a great name, hyphen or not.