How soon you want your solar project done? I think the solar roof has a much longer wait time depending on your location. A new shingle roof and panels will be quite a bit cheaper with much faster completion time. The solar roof costs more and you need to upsize the capacity because the tiles are not that efficient. In my case, I would break even on panels in under 5 years if I pay cash, I've decided not to even think about break even with the solar roof, like everything else in life, I like the look and just have to pay for it. The only pain is the wait.
Check on your utility for the last 3 years, or as far back as you can to see how many kWh you use annually and get the highest one as target system size, forget about power in kW because that is almost meaningless depending on panels or solar shingles. Go to the Tesla order Solar Roof and size your system size, it would give you estimated kWh annually, take that number and multiply it by 0.755, that would be the size the design team will mostly come back with. eg. The order page will tell you a 6 kW size would yield 9289 kWh annually, but once you submit the order and the design will come back with 7017 kWh, that is about 0.755 of the estimate. So working it that way to get a system size that will meet your energy need. Utility company will always tell you to get 95% or less for solar and most would not let you get more than 110% of solar based on your past consumption. If you have NEM then I would size 100-110% of past consumption.
Google project sunroof and PVWatts are useful for a rough estimate on a system size you need, but I found PVWatts more useful because you can tune where your solar cells or panels are. In my case, Tesla put all solar cells facing east instead of west, it kind of make sense because the roof will get sunlight from 8:00am to 2:00pm while on the west there are lots of shade and actually will get less sun. When I set the east facing direction and some other parameters, it is quite close to the Tesla design.
As for the deposit refund, if you really want to go with the solar roof, call the solar panels number and tell them you want to go with the solar roof and ask them to help you cancel the panels order and process the refund for you. They refunded my panels deposit but it will take at least 2 to 3 weeks. Tesla has a lot more business than they can handle, especially with the recent panels discount they are cheaper than anyone else. I guess the deposit is just a way to screen out tire kickers with no serious interest. My suggestion to you is to get a new shingle roof and install panels, you will get it done much quicker and a lot cheaper. They just told me the solar roof backlog here is at least 5 months.
