OK, so they've gotten paid about $6,000, and maybe they live another 15 years. They'll net $24,000. The amount they are saving on the power bill is about $300 a month, so that's $72,000 in savings plus the $24,000 they got paid, so that's $96,000 in 20 years from a system that cost $40,000.
Not a great ROI, and that's assuming they live to 90 (it'd be nice). I don't think I'd invest $40K to get a return of $400/month. Probably doesn't even keep up with inflation. Let's hope the batteries last 20 years. About the only upside is that they'll have their own power during an outage - that's what the batteries do for you. And they will be immune from future rate increases. I had solar on my house in California. No battery back-up so also no power during a blackout. I bought it when I was working so the 30% tax credit made sense + the utility was kicking in another 20%. Now that I'm retired, a tax credit is not a big deal. My monthly bill prior to solar was over $500/m in the summer and with the exchange with PG&E for my excess power, using time-of-day rates, was more attractive than it is now.
What's a 20 year old solar system going to be worth? Two decades from now will roof mounted solar panels be the 2038 version of a 7' diameter satellite antenna? My panels were guaranteed for 80% rating for 20 years. The inverters were good for just 10. Look how far computers have come in 20 years - where's solar predicted to be?. In my opinion (and it's worth exactly what you're paying for it), stand alone systems don't pay unless you're off the grid and then you don't have much choice. Of course, there are extenuating circumstances where you require uninterrupted service but even then there are options.
Well, as to battery cost...that's one of the technologies that's growing by leaps and bounds these days. Look at Tesla. Hell, look at Erik and what he's doing now! I see batteries following in step with the rest of tech - cell phones, laptops, data storage - and getting cheaper, and smaller, and more powerful by the generation. So while there will still be replacement costs, I see those costs getting a) lower and lower with each generation, and b) generations living longer and longer as tech advances. And I'm budget-disciplined enough that I'd take the first $xxx.xx of the payback money, stick it in savings, and keep it as "escrow" for the battery replacement event. It's "free" money as far as my budget is concerned so I won't be "missing" anything by socking it away at first, until there's enough to cover new batteries when needed.
At least, that's my naive theory on the whole thing, with only moderate research thus far.
If I save $3600/year in electric cost, and get paid $1400 in energy put-back, that's 5k a year. Pays off a 50k system in 10 years. And more importantly, frees up hundreds of dollars a month from the monthly budget. I live in a power-strong area with very few outages, so all I'd really need/want battery-wise is for the well pump, fridge, and possibly HVAC/heat pump (for those dead of winter outages - but I can always shut off and drain plumbing if it goes that far).
I'd argue that as battery tech improves, the price moves up with it. I looked at replacing the deep cycle lead-acid batteries in my travel trailer with lithium equivalents. Unbelievably more expensive.
50k with a 10 year payoff is about right by all the research I've done.
Not the best investment deal but not bad.
I'm predicting lithium batteries are going to be replaced in stationary storage soon.
Lithium includes a range of chemistry with different power to weight ratios & likelihood of catching fire.
Motorcycle and car application will be lithium polymer variants because of weight, but there's no reason for caring on a home storage system, and despite lithium being a common element, there are limited mines & sources. ( like the rare earth elements in the motors )
Today. April 2018, save your bucks & only switch from lead acid to lithium for highly weight restricting uses. Like airplane starter & avionics batteries.
There's a small number of companies making these things right with the robust build needed. And the wrong charging system will ruin the lithium cells.
I'm not putting down new batteries. We are just early days yet in development and training in proper use.
An Iron Acid Edison cell would actually be best for a home storage, "get you through a couple of grid down days" application. The poor self discharge nature isn't an issue there. But no one makes them. Obsolete.
I still have the studded tires on and they go illegal Tuesday. But I've run through ice slicked highways late at night all month, so I'll just plan on getting them changed next week.
In the last two years, the planet's temperature has dropped .56 C. Nearly erasing a half century of natural warming. Yet you know they are going to lie again and claim it's the warmest year on record. Again.
It's probably, almost certainly, just a short-term fall, related to El Nino/El Nina currents in the Pacific.
As a skeptic, I recycle grocery bags, heat with a high efficiency heat pump, and bought a car with the lowest environmental impact I could find. ( that the company lied about that was not my doing ) My motorcycle gets 50+ mpg. And no aircraft beats mine in carbon footprint. ( no engine on board )
Al Gore's home used more energy in a month than mine all year, and his private jet usage has literally infinitely more fuel consumption than my glider. ( unfair comparison, I can't cross oceans with mine ) Al's carbon footprint for going to the store is also a dozen times mine, but I don't have Secret Service agents in armored vehicles, and he does....... And we pay for it.
Now the Prophet Gore claims to be better than me. He buys carbon offsets, he claims, that makes his consumption neutral. But he buys them from himself, so simply takes money from one pocket, and puts it in another, and declares himself literally Holier than thou.
He is a typical True Believer. He demands my money for his notions of government charity, at the point of a gun. But gives very little of his vast wealth to others. No sacrifices on my part are spared to meet his demanded level of holy purity. None are required of him.
I'm a slacker on my tax exemption for charity. I don't bother to keep track of the pittance I give. I'm certain most folk ( especially here ) give more in proportion. Progressives are certain that they give more, since isn't their very presence a blessing in the land?
Another mandate from a bureaucracy to improve the bribes to themselves. ( bet ya ) More incentive to live in Texas.
Otoh, all new cars will come with backup cameras. I predict this may save one child from being backed over playing behind their parent's car. ( and that tragedy will still happen to others. No amount of technology cures carelessness. )
There is a mediocre spy novel where a N Korean nuke is going to be used to trigger the eruption & slide.... I never finished it, ( rare, for me, I read fast ) I assumed the badly written heroes saved the day. I don't know where the book is. I was reading it in the porta potty at a camping event. ( these things can take time when you get dehydrated )
Backup cams will only translate into more "He hit me as I backed out of my spot" accidents. When people get trained to look at the dash, instead of out the windows at what's actually AROUND them, we'll probably see an increase in accidents. Sure, folks probably won't back INTO as much stuff, but pulling out in front of others...?
The unintended consequences of these "well meaning" laws is often the opposite of the desired results. That is assuming the stated goal is the real one.
And often it is not.
There is an Urban self superiority complex provincial mindset that doesn't want cars to exist. Provincial, in that they can't imagine anything different than their experience. Most of the planet doesn't have mass transit in high density living.
I shop for cars on Craigslist, and know that a ( for example ) N. Carolina car with high miles is in good shape, since it's had a fifty mile daily commute. Boston urban dwellers may never get 50 miles from home without a cab ride to Logan airport.
Manhattan islanders think they are the center of the universe and all else is a pale copy. Perhaps. In dystopian future stories.
Don't get me started on LA.
Most of the country commutes to work. I've lived 55 miles away, and 15. And 3. Funny that I never rode my bike to work when it was 3. Not worth the effort to gear up and never warm up enough to boil the water out of the muffler. 15 miles? You betcha.
I understand the urban provincial mindset that wants less traffic & car ownership is not worth it.
They, OTOH, don't understand the suburban need for individual rights of passage. Much less the rural need for actual trucks to move actual loads.
Guess who writes car regulations? Yep, subway living folk who now have chauffeured rides.
That's the billionaire who surrounds himself with heavily armed guards, while paying millions to take your guns away.
I recall his staff wrote the Clinton so called assault weapons ban, and declares bayonet mount a reason for a thing to be evil. Even though bayonet deaths in the U.S., outside a few cases where the Army was used to break up strikes, are...... Zero.
Honesty is for the Other guy to ruin his plan to harm you. Not for Bloomberg.