I'm no expert, but I can tell you what we decided. We have a state subsidy which paid for about half the cost of our panels up to 5kw, so that's what we went with. To get the subsidy, it required us to be on the grid so we feed the system when we're not using the power we generate. We bank what we don't use, and then, come winter, we draw down the bank before we start paying for power. We don't want to be a net generator as they pay you wholesale, but you buy retail, so it really doesn't pay.

We also got a 30% tax credit off our income taxes for the solar panels, so we figure, assuming no electricity price increases, we have about a 10 yr payback. What other appliance actually pays you back? We also have geothermal heating/cooling, so our only fuel cost is electricity, so for us the panels really pay. If we were only using the electricity for lighting, it really wouldn't pay for us to go that way. We also live in the area of the country with the highest electricity costs, so the payback is worthwhile.

If you go off grid, then you have to think about batteries which are heavy, take up space, require maintenance and present their own environmental challenges.

If you get a qualified solar panel company, they will do all the calculations for you including what your subsidy will be, how efficient the panels are, how much you should expect from your location, etc. Just be careful as there are a lot of fly by night operations out there and the better business bureau has lots and lots of complaints so check with them first.

In our area, 3 towns got together and tried to get residents to do a quantity buy which brought the price of the panels down considerably too...they pre-selected the installer so you didn't have to do any shopping or comparisons....I think they ran it for about 4 months.

Going off the grid completely is extremely expensive. Need major batterypacks--the major expense, a nongrid tied inverter and a backup generator in case too many bad weather days. There is no chance of this costing less than several times the utility electric rates. Only practical in remote areas where grid unavailable. If battery prices were cut to 10% of what they are now, then would start getting more interesting!

Producing enough to balance feed to/from grid is easier, but requires a lot of unshaded roof with southern exposure. You also need to check local utility policy. Production is seasonal. You would produce more than you use in the summer and use more in the winter(typical-details vary with a number of parameters). Some utility policies may not let you carryforward surplus.