Before ringing round and taking quotes take your time and find out the dimensions of your house roof and think about what sizes you what or can afford. You can add too the system as you go so starting off small mite be the best way to buy. For best results you will need a south facing roof but as you know by now you can solar set up any were if you have an a-frame and anti theft attachments because face it if its not nailed down it will go missing so ask about this when inquiring.
As for business's it all depends on budget and what you want out of your solar system. Solar industry is growing rapidly and solar panels are being use more and more by Business to try and bring down the costs. The solar panels vary in size and construction normally roof installation will be based on solar panels of around 1.5m by 1m generating up to 200watts. if you have more than 20 panels you are a power station warehouse roofs have the big bonus of a large area and can be used to make money as well as help the environment.