I am planning to order tesla solar, however, my friend recommend me to buy solarwork.org, look like it's more cheap? anybody know what's difference? thank you.
can't find the server at www.solarwork.org
Cheaper to buy may not be the best choice for such an expensive, long-term project.
Where do you live? Energy Sage (https://www.energysage.com/), Angies List, or Yelp may be able to steer you to some other local companies for analysis and quotes.
Pay close attention to the longevity of the warranty, and if it's backed by the equipment manufacturers. Warranties backed by the installer are often not worth the paper they're printed on, as installer companies come and go like the tides.