When is the right time to buy a new/emerging technology?
As you said, the next generation will be cheaper and more efficient. Same for the generation after that. From a financial standpoint, there isn't a steadfast theory that supports when to buy the technology. It comes down to primarily personal issues.  As far as I know, Musk's claims about the cost were relating to a traditional slate roof, not a traditional asphalt shingle roof. I can't recall if he explicitly said one way or the other, but I have yet to see any math that supports a comparison to asphalt shingles. If you look at all of the demos and marketing material, it's comparisons to various styles of tile roofing, which is already more expensive than asphalt shingles.  Do you feel it's worth it to invest now, or do you think it would be more worth it to invest later when the costs are lower? A new roof will last 10-20 years (if not longer...I'm not a roof expert). Do you need a new roof yet? Are your electricity bills high enough that the cost of going solar will offset it enough? Can you sell unused power back to your power company? I could go on, but I think you get the point. It's entirely a personal decision, and not one that will have a definitive answer. If you keep waiting to make a purchase because you're worried that the next generation will be cheaper and more efficient, then you're never going to make the purchase.
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When is the right time to buy a new/emerging technology?

### Response:
As you said, the next generation will be cheaper and more efficient. Same for the generation after that. From a financial standpoint, there isn't a steadfast theory that supports when to buy the technology. It comes down to primarily personal issues.  As far as I know, Musk's claims about the cost were relating to a traditional slate roof, not a traditional asphalt shingle roof. I can't recall if he explicitly said one way or the other, but I have yet to see any math that supports a comparison to asphalt shingles. If you look at all of the demos and marketing material, it's comparisons to various styles of tile roofing, which is already more expensive than asphalt shingles.  Do you feel it's worth it to invest now, or do you think it would be more worth it to invest later when the costs are lower? A new roof will last 10-20 years (if not longer...I'm not a roof expert). Do you need a new roof yet? Are your electricity bills high enough that the cost of going solar will offset it enough? Can you sell unused power back to your power company? I could go on, but I think you get the point. It's entirely a personal decision, and not one that will have a definitive answer. If you keep waiting to make a purchase because you're worried that the next generation will be cheaper and more efficient, then you're never going to make the purchase.