Solar estimates

I finally got through the final analysis of the current estimates last night. Here are the results:
One company came out and did an evaluation but never got back to me with an estimate. One company had a rep come out and basically told me that my roof needed work before the solar could be installed and even then they could only get a 2kw system installed even though I mentioned trimming back the tree next to the house. I'm getting the roof inspected as soon as I can to make sure that isn't correct. And I still need to verify a couple of things but this looks to be the end result.

Of the three companies that have been cooperative and helpful these are the numbers:
Rec Solar 8000W $25,000 including all fees and taxes but not including tax rebate.

IPS 9900W $38,115 plus taxes and fees (~3% of total) not including tax rebate

SRE 8000W $30,174 including all fees and taxes but not including tax rebate

So the question is still how much financing I can afford, but it's unlikely I'll decide to spend roughly $14,000 in order to get an additional 1.9kW of power. I'd love to have the additional power, but the payoff just isn't worth the expense, especially with all the great solar technology that is being invented right now.

I don't think I've mentioned the problem with the tree here, so here's a bit of info about that.
I have a black walnut tree about 10' from my south facing roof. It's not huge, but it does shade the roof where I want there to be solar panels. So it'll have to be trimmed severely, cut down or moved before I get the solar installed. I'd really rather not kill a tree that I don't have to kill, and I don't think I can afford to have it moved, so I'm hoping the amount it needs to be trimmed won't kill it and won't make it completely idiotic looking. However...black walnet isn't really a tree I'd have chosen to put in my yard. They don't provide enough shade for how big they are, they don't have leaves enough of the year, and they drop annoying nuts in the yard. On the other hand, it's kind of fun having squirrels running across the roof. That would annoy most people, but I think it's funny.

Shade is a tricky thing with solar panels. Each panel is made up of groups of chips. And then the panels are in groups like the chips. So, if you get a spot of complete darkness that covers enough chips it will shut down not just the chip that is covered but the group of chips it is in. If enough groups shut down, then the panel shuts down. If enough panels shut down, the the whole group of panels will shut down. So if you have even a small amount of very deep shade on the panels, there is a chance that from that chunk of deep shadow you could get a pretty significant percentage of your solar array to stop producing energy.

The reason this happens is that each subset has to produce a certain amount of power in order to trigger it's connection to the others. If the chip doesn't produce enough power to get beyond that threshold it never turns on and so no power flows out of it. That scales up in the same way all the way up to the entire array.

So now I am waiting for verification of a couple of things, then I have to start trying to get the financing and hope that the estimates don't change much or at all, and that they are accurate and I can afford to pay for solar. Otherwise...time to start saving up significant amounts of money.