Just for reference, you are still making some errors with your figures. Not picking on you, just trying to help as these things need to be right if you are going to get good information:
... And yes, a 3000 KWH solar system ...
I'm pretty sure you mean the 3 kW system you talked about earlier. That is 3 kW, which is also 3000 Watts (the k is a 1,000 multiplier). You posted a 3000K is 3 million.
Also, solar panel systems are specified in kW not kWH (hours). The kW tells you the peak power they could deliver in direct overhead sunlight at that moment. The manufacturer has no idea how many hours that sun is available to you (probably never actually, it really is a peak number), so they cannot rate the kWh delivery. For that, you need to go to a calculator for your installation, taking into account your roof exposure, angles, and local sun conditions.
In an earlier post I used a rough estimate of 25% capacity factor. Capacity factor is the % of "nameplate capacity" you get over time, taking into account day/night, seasons. So a 3kW system at 25% Cap Factor would produce an average of 3000*0.25*24 hours/day * 30 days/month = 540 kWh per month. The 25% may not be a good estimate for you, you would need to verify that - there are on-line calculators.
People talk about being able to get solar installed for ~ $2/watt, so that should be in the neighborhood of $6,000 installed, but there are lots of variables.
... But just as the panels themselves have a certain efficiency (18-22%), the system overall also has an efficiency percentage: it is not producing 24/7. And even when producing, the efficiency changes over seasons (sun tilt angle) and years (degraded components over time by being fully exposed to hot/cold temperature variations; storm damage, etc). ...
Be careful not to double count. The efficiency of the panel is already accounted for in the nameplate power output. That is, a 3kW system that uses 10% efficiency panels will produce the same power as a 3kW system that uses 20% efficiency panels. It just takes twice as many panels (and they will be cheaper, so look at overall installed costs).
Those online calculators should take most/all of that into account.
... The cases I've read of achieving the "free electricity" do tend to be the $30K+ systems involving 30+ panels. And yes, it's contingent on the arrangement with the corresponding power company -- if you can get a credit on the amount of surplus that the system produces. But the form of that credit is a bit nebulous (i.e. not all power companies are consistent in how the surplus is credited back to you).
....
"Free electricity".. after you pay $30K. Not sure why people think like that (I realize that's why you put it quotes, but still). Didn't someone mention dividends as "free money"?
Heck, I'll guarantee you free electricity for life (in that residence), use as much as you can/want (w/o upgrading the panel beyond 200 Amp 220V service!). I just need a deposit of $4,000,000.00. Then it's "free"!
And the fine print with the power company is important. If 'excess' is not accounted to you the same as your purchased rate, it probably does not make economic sense to put in a system large enough to provide an excess. Also, the fine print might be changed over time. I think we are seeing some utilities needing to charge more for a monthly connection fee to offset the solar users who are kind of getting a free ride on the grid (that's not a judgemental comment, just an economic one).
... That said, I do think it is possible for conditions to exist that tapping into a 401K briefly makes sense ....
JMO, but I think you would have got better, more focused responses if you just stuck to the economics of the upgrades. Once you determine if any make sense on their own, then you could look at how to pay for it.. If they don't make sense w/o borrowing, the certainly don't make sense after borrowing.
... In my view, the individual panels should run around $300 (I see a range of $78 to $495 on the web -- so I pick a "reasonable quality" average of $300, with even that being a tad high). So even if you double that price to account for frame, wiring, inverters, insurance, tax, install, etc. a 30 panel system is $18K. Add a because-other-people-need-to-eat markup, then the $25K range isn't so unreasonable (plus extra costs associated with the actual power grid connection, which yes may involve some permits, i.e. a couple grand). Tax credit that 30%, and things really might start to make sense... I'll mull it over further. ...
Yes, I've heard of $1/watt prices for panels, but installation takes most of the estimates I've heard about over $2/watt installed, and that's the low end. So expect at least a doubling for installed costs. But you really need a firm quote on your particular situation (roof type, angles, etc).
-ERD50