What's the difference between a tax refund and a tax credit?

We've had quotes from other companies that aren't licensed general contractors or electrical contractors.  What's the advantage in choosing Windsong Energy to design and install our renewable energy system?

What's the difference between grid tie and off grid?

What are the current tax credit incentives available from the federal and NC state governments for solar photovoltaic renewable energy?

We've got a lower estimate from a competitor that claims they're a volume dealer.