on grid systems are much cheaper and don't have the drawbacks of the off grid. however the potential savings are also less.
a 4kw on grid system starts at 5k$ and then you'd need to have it professionally installed for another thousand plus permits and fees from your city and local electric company rack up another 500$.
on grid systems work fairly simply, solar by day, grid by night for the most part. anything you over generate gets you a credit by your power company and usually helps off set the night time usage. dunno about grants but for me and my wife I'm thinking about it, I'd need the 6kw setup which is fully installed for 9k. current electric bill is hitting 300$ for june.july august, 120$ for october, november, march, 160$ for december, january, february 180$ for april, may, september (rate hike for summer months really kills us)
so annually we pay 2280$ for electricity. which means in 4.5 years the system payed itself off.
not as astounding as some of the off-grid setups but still hurts especially in this economy.
so brianhellno hit it on the head right now unless you've got serious cach laying about, conservation is where it's at.