It looks like you didn't discount the rate of return for the investment value of the initial $20,000+ cost for the system. I would have used a conservative return of about 4 percent, which would cut your rate of return about in half. I have found that most payback calculations done by contractors and even by independent organizations do not include the potential investment value of the system cost. So, $20,000 invested in a solar system today will be worth zero in 20 years. But, $20,000 invested at a rate of return of 4 percent will be worth about $44,000 in 20 years.

Well, As someone that DID get solar, I am highly satisfied! I had 38 panels installed that will last at least 20 years...well at least the warranty is 20 years. They have already been thru hurricane Irma with no damage. My payback will be pretty quick because I took advantage of the federal program and received $10,000 dollars back on my tax refund when I filed. I thought it was just going to be a tax CREDIT, but I actually got the whole amount refunded to me. My payback comes out to 8.4 years before I break even. I have no electric bills, $0.00 from April thru November and roughly $35.00 bills for December, Jan, Feb and March. Duke holds my excess energy generated in the summer for use when the days are shorter in the winter time. I can monitor my usage daily from an app and see if there are any issues with any panel. If you are elderly, like my mother, I recommended that she NOT get solar because she may not live long enough for the payback. Also, I installed mine on a brand new 40 year roof so I checked all the boxes. Don’t install panels on an older roof, you’re asking for trouble. These are just my opinions. I love having little to no electric bills!

What about pools?
 

Thanks for your answer.

Im interested to know if a heated pool changes the math enough to make it worth the investment.

Solar hot water
 

Has anyone installed a passive solar hot water heater? Since hot water can be 30 to 40% of an electric bill that seems like an inexpensive way to save $$$

Solar Panels
 

I have Tesla solar panels and two Tesla storage batteries installed on my home. The home is fully powered as well as my two Tesla vehicles. I receive a credit for the power that is put back in he line from SECO.
The Tesla system is a SMART system, I can control it with my smart phone. It is also monitored by Tesla. When a storm is approaching it will store energy in the batteries, so power is available if needed. I have spoken to native Floridan's who were without power for 10 days during hurricanes, it was not a pleasant experience.
A tax CREDIT is currently available, and it will reduce the cost of the by close to one-third.

Perhaps, the reason is the pool heater, which I presume is a heat pump, would send your incremental use into the penalty rate of 13.7 per kwh, vice 11.7. further you could schedule the pool heating during prime solar generation hours. Meaning you are using solar solely to heat your pool. The penalty rate is above 1,000 kwh for SECO customers.

I can't say for a fact, though, as I have gas for pool heating.

The overall idea is to use the heavy consumption electric appliances during solar hours, dry clothes, charge the car, super cool the house.

I have two 40 watt solar panels that are NOT attached to the roof. I have them in my backyard. They are portable and can be moved during windstorm or hurricane. They generate power into a battery pack on my lanai. I can power my refrigerator and even a second refrigerator during a black out. However, it is convenient not to have to worry about a thawing freezer during a blackout it is an expensive folly.

This topic has been debated several times before , there are valid reasons not to do it such as your age , the age of the roof ,your personal decision as far as helping out saving the planet (coal is bad) it is certainly not an investment and I don't think that anyone would buy it as an investment but it will pay you back don't believe for a minute that it will take 20 years . I have a 2200sq ft home have a 15x30 inground pool with heat pump (wife likes the water at 85 all the time ) I just had a system installed in December 34 Panels 11.05kWp I was of course happy to receive 30% back from my fellow taxpayers (thank you ) so far I just have to pay my 10 dollar connecting fee to Duke Energy The installer estimated my system to be paid back in 8.5 years I am very satisfied todays equipment comes with 25 years of warranty on Equipment ,Performance and installation could I have used this money and invested it …….. sure but I already have a lot of money invested therefor this argument does not apply to me ...just my personal opinion

Several people who have solar systems have said that they have a 20 or 25 year warranty. Is that a full warranty for parts and labor? I don't know any company who sells mechanical/electrical equipment who can provide a warranty anywhere close to that. I would be very skeptical that a solar contractor really intends to honor their warranty, or that they will even be in business in 20 years. It sounds too good to be true.

Suggest you read up on IRR. An 8% IRR means that all cash flows are discounted by 8% to result in a NPV of zero. In other words, If I were to calculate the NPV using 4%, the result would have been a positive number. Or in this case, If were to place the initial investment in an 8% tax free investment and take out $1750 per year, it would last 20 years. Maybe you are saying that my 8% return is 4% better than if I invested in an instrument that yielded 4%. You are correct. You are also correct that the potential investment value in the initial investment is not included in the payback calculation. I did not mention a payback period in my post. I'm not a fan of payback period when doing financial calculations. I prefer IRR.

All I am saying is that the potential investment value of the initial cost of the system is very important, but it is almost never included in any financial calculations by those who promote solar systems. If I were to invest $20,000 at a rate of 4 percent for 20 years, I would have more than enough money to pay all of my electric bills for the 20 year period.

A $20,000 investment in a 4% annuity pays $1,472/year for 20 years. Is your electricity bill lower than $1,472/year? Also, $1,472 is less than the $1750 of electricity I produced.

Duke gives you back what ever you give them. They do not buy at a low price in the day and charge a high price at night. At the end of the calendar they pay you for any excess you gave them at a very low rate.

Yes. My electric bill is about $1100 per year for an all electric house. But, it is a small courtyard villa.

solar panels, finance and the cost of the maintaining the old back up system
 

Good morning, as the debater of concepts with some experience and some expertise, currently working at an electric and gas utility company in finance, doing some regulatory reporting, doing some investment analysis, assisting in rate setting requests:

Observation: always interesting to read who uses a financial reason, who uses a faulty financial reason, and who uses an emotional or generalized reason as their valid point of view. Therefore, as a finance professional supporting or blowing up investment requests, not everyone should financialize their decisions about investing in solar power. There are good non financial reasons to invest in solar power. If you want to invest in them, please by all means do so.
But as in most individual decisions, there is a consequence of many individual decisions which most individuals can't see now, or in the future. So, please beware of unintended consequences of the progress of solar power, which I will explain the concept.
Utility economics:
First, current utility industry is broken down between generation systems, transmission systems, and distribution systems. Generation systems and transmission systems are regulated by FERC, which means the federal government. Retail generation and Distribution systems are regulated by the state department of utilities, different names in different states. By US governmental statute, utility companies are guaranteed a profit rate of return. The utility company applied to the state for the rate structure to charge its customers. The state government approves the rate structure. If the state government doesn't approve a rate structure, the utility has the right to sue in court and the judge will decide the rate structure. If the request is documented well enough and falls within the statutes, the judge can overrule the state regulatory body. likewise the state can pass legislation to force a utility to do something, like accept retail generation, which can bankrupt a utility. True story: State of New York required Niagra Mohawk to accept generation from alternate utilities, which increased their cost of supply above break even, and bankrupted them in the late 1990s. google it if you want, my source is one of the finance controllers who was there. So regulators control the system pricing, whether you like it, agree with it, or not.
So, how does this effect you? first, the initial distribution system was not built for two way electric flow. The unintended consequence is that a different electric usage and monitoring system has to be developed, and then installed, and then monitored for billing. This new system took time to design, develop, install and use. Yes, there was and still is a cost which is recovered with your current distribution rates. And in older systems, the 1950s mechanical switching systems are breaking with the quick reversing between generations flows and sun covering the solar panels. More investments, which the utility company is guaranteed a rate of return, remember from above? so again more background on your now backup system price structure Also, there is a control structure to energy flows, as there is no place to store/put in inventory, electricity for future use, at scale. (home batteries are not the point, FPL system storage is the concept) so the control structure is designed to keep stable system amount available at all times. That control structure now has to include the new uncontrollable incoming generation from your panels. That is a very large investment and task as solar comes on line, as the weather is not stable so neither is your generator to the big system. More investment and technical expertise needed, therefore more increase to your now traditional electric system, or your backup system.
So, the punch line: as more solar comes on line from retail sources, the less traditional energy will be consumed. Given that the distribution system to your house has a very large maintenance cost, million of miles of wires, millions of poles, thousands of transformers, millions of meters, usage collection systems, thousands of remote cell phone monitoring devices, etc, to cover those required costs to your backup system, with a guaranteed rate of return in order to guarantee 24x7 availability, traditional electricity costs will continue to increase, in a non linear, exponential way. As the percentage of customers with solar increases, a smaller traditional base (denominator) usage will have to cover the cost of the backup system, to be available at night, or during storms.
So unless you go off the grid 100% you are slowly for now, raising rates to everyone else, which includes all your grocery stores, retail stores, government offices, public lighting, etc. But the other point is that your current net metering agreement is subject to review and rate adjustments by the governmental regulators. With that uncertainty, you probably didn’t model those real long term changes into your somewhat flawed NPV or IRR model. (For the technical financial types, NPV is primarly a bond pricing model, with stable and predictable cash flows. IRR is better for a variable cash flow models, but still has a weakness of not separating out the different rates of investment return versus financing rates. Therefore, proper detailed financial model should use the MIRR formula to give a more correct answer. But that is the least of the return analysis)
If for any unforeseen reason that solar panels degrade and become a fire hazard, your insurance rates will increase, which may wipe out all the savings, and tesla panels have had lawsuits for roof fires.
The risk of solar investment return is that the current rates, both generation (wholesale) and usage, (retail) are stable. But that is not a guarantee, and with the potential for your usage rates to rise faster than inflation in order to maintain your backup traditional system, and your wholesale price to not go lower, your entire model is based upon the current spread between wholesale and retail pricing and your percentage of backup usage. With regulators being able to change that on a whim, or as a result of an unforeseen event, the societal impact of increasing solar is higher traditional energy prices for everyone.
So in reality your model is only good for about 5 years max. other than fed bond models with guaranteed cash flows, most commercial investment models good for 5 years. The world changes very fast, the cash flows are very uncertain with weather patterns, and cost and price subject to government changes. The best societal solar investment is in large solar farms which have critical mass, which feeds the system through a single entry point for control and monitoring the system, but will not eliminate your backup system cost, and the cost of maintaining the distribution system, unless you go complete off. . .
Which is why, if you want to invest in solar, go for it, but from a purely investment point of view, the investment is very, very difficult to predict and guarantee any payback or investment return to make financial types comfortable with a reasonable return. But please don’t think that your current year savings is the only point for evaluation for the next 10-20 years. . .

Sportsguy