Solar Panels for my home

A also wrote the wrong units. It should be

1.6 kWh/watt*year

meaning every year, each watt produces 1.6 kWh.

If you are feeling really cheap (like me,) you can install the panels yourself with a friend and just pay an electrician for the hook-up. You will be surprised how easy it is.

 

I know you meant 1,6kWh/W per year.

I am cheap and wish I am handy to install it myself. But I don't have the confidence. My house is with 10 feet ceiling for both 1st and 2nd floor, I really don't feel comfortable to install on such high roof. So I have to hire someone... Thanks for suggestion, wish I could DIY

 

When we work on roofs where the injury risk is high (e.g metal, from slipping), the homeowner rents a set of ropes and climbing gear for the workers.

 

Solar is a risk. It's a commodities market risk. The commodity is electricity and the risks are associated with the cost of power and if you can sell it within the infrastructure. The $16 a month fee is pure BS. That's a gravy annuity straight into the seller's pocket. The question is, will the laws governing the sale of solar electrons into the power grid change and/or can the sales person guarantee the 8.5 year payback?

The answers are yes and no. Yes, the laws are changing as power companies see see power being offered into their systems that pays for none of their infrastructure. Some power companies are levying fees, others won't pay for power generated at times during the day when their own generation infrastructure provides a surplus (they have solar too), or the rates they pay vary according to demand. And the sales person WILL NOT guarantee your system will ever pay back. The sales persons are typically selling loans, not solar power. The solar power hardware is just a way to get you to borrow money. Here's a test: Ask the sales person if they are required to have a lenders' license. Here's another test: Tell them you want to pay cash, install the system yourself and do your own installation. They will run like a scalded cat.

And here's another variable: will the solar company (lender) guarantee the output they use in their payback calculation? I have talked to numerous solar power sales persons and they explicitly will not. These dudes are loan sales persons, not engineers. And the number of factors in a typical solar power output calculation guarantees that even the engineers are guessing and the "estimate" is usually low over time and/or totally overstated.

Buyer beware. Make sure you are buying the product you think you are: Is it a solar system or a loan? Is a system that will deliver what you want (a reduction in the cost of your consumption of electricity)? Is the hardware guaranteed to provide the stated output?

 

There are lots of numbers in there. Tax credits, interest charges, a $16 fixed annuity payment (which probably goes on forever), payback period with unknown variables, business environment risks, depreciation, etc. Referral dollars? Hmmm.... is this Amway?

 

It's a commodity issue. You are the farmer, you are harvesting sunlight converted to electrons. You financed the cost to produce the electrons. That's risk. Now you have to rely on the "gods" of weather, the efficiency and reliability of your tractor and fertilizer over time (the solar panels) and the market demand to see if you make money. Some will, some won't. If you don't, you still pay. And if you want to get out, you will need to decommission the system. That's also costly and risky.

Frankly, if you were to invest that $15,000 in insulation, efficient appliances (or reducing or eliminating your use of appliances), good windows, a zoned heating system, sweaters, a nudist lifestyle when it is hot, etc., you would be better off, or at least be in a less risky position. And hey! That nudist lifestyle is free.

And regarding electric cars that people are figuring into this equation, the savings are probably bogus. Do the calculations, right now it is cheaper to drive a hybrid or a plug in hybrid than rely on the ever rising cost of power. At least with a PHEV you get to choose to plug in or fill up at will. The cost of power will continue to increase over time. The cost of gas will fluctuate. Even if electric cars make sense now, soon they will be victim to the rising cost of power and the shifting of cost increases to EV owners as they tax the power grid.

And don't forget range reality with electric cars. Which creates range anxiety. Which results in inconvenience, crabby spouses and, inevitably, the use of f-bombs when the EV has to be towed to a power source, wiping out any economic advantage.

 

The demand is my consumption.
Weather is irrelevant over the lifetime of the system.
The components have efficiency and duration warranties.

So all told, I find your construct less than helpful.
I prefer to calculate the amortized cost/kWh of the system. Mine is about 2.5 cents/kWh for clean energy.

I'm delighted; and I'll continue to be delighted even if my neighbor gets a better deal in the future. Why ?

1. The future is uncertain
2. In the meantime I don't care to continue polluting
3. My purchase today facilitated a cheaper purchase by someone else tomorrow.

 

Can you provide some more detail on how you get to that value.
If it costs $20K to install a 7KW system that lasts 20 years...
The 7KW system would generate 11.2 MWh/year using the above 1.6KWh/installed Watt factor.
For 20 years that's 224MWh produced for $20K or about $0.9/KWh

 

Sure.
First though, did you include your tax credit ? If not then your amortized cost is ~ 6.3 cents a kWh. That is really cheap electricity.

In my case,
I paid $1.5 a watt after tax credit for my (mostly) DIY system
Collect about 1.8 kWh a watt*year
Decided to amortize over 30 years based on my panel degradation warranty.

 

Congratulations. That's a great deal, as long as you either consume all of the power, or the utility will buy the excess. Utility buyback in the future is a question. You don't have a contract with them for the 30 year period. They have rate setting power, which in the future may not pay you for your electrons, or may pay you far less than they charge you for power from the grid. If you are storing your excess electrons in a battery bank and using them (at night and/or during peak grid demand during the daytime) you are OK because you have a market for your electrons -- yourself.

A portion of your value is not captured in your costs, which is your labor. If you wanted to be picky, you would add the cost of market labor to install as a fixed cost. But that is how DIY'ers save money and reduce their costs.

The 30 year amortization is a reasonable assumption as long as you take into account the loss of output over time (which decreases your return as the panels age).

I will conclude by stating that your case is not normative. It is an anecdote, except for you. For you it is evidence (sample of one).

 

I don't know where you live, but in my state the PUC has the power to set rates, not the utility.

 

I live at Dana Point, CA. Probably the same here, but the PUC or whatever it is called here, is always pretty much granted their requests. My point is that you have no control of the market for excess solar electrons. That market is controlled by forces over which you and I have no control. You could be compromised or cut off from the sale of solar electrons at any time. That is risk. Probably one that you should insure against, if you can.

 

Most weekends of the year I volunteer to help neighbors put up PV. They end up paying about $1 a watt after tax credit. Perhaps I should leave a card with them mentioning the avoided labor costs so they know how much the electricity is really costing them. As for me working for wages instead, my reality is that I work as much as I want and no more. My volunteering and DIY projects are a choice how to spend my free time.

As for 30 years, I normalized to new STC the integral from 100% down to 80% based on the manufacturer reported annual degradation.

 

Nah.
Grandfathering covers people for a good 10-20 years and by that time who knows ? I can already store excess production in my EVs if I cared to.

 

Grandfathering is a myth. I am not speaking out of ignorance. See this article, one of many.

 

No myth; and as for Nevada, you are not keeping up:
Nevada Legislature Passes Bill to Restore Net Metering for Rooftop Solar | Greentech Media

AB 405 would also allow net-metered customers to lock in their rate for at least 20 years, eliminating the risk that rates could change retroactively. Other consumer protections are also included in the bill, like the requirement for solar companies to offer a 10-year warranty and to provide transparent information as to how they calculate customer savings.

Furthermore, the legislation ensures that net metering will remain the law of the land in the event Nevada voters decide to deregulate the state's electricity market. It also mandates that residential solar and energy storage customers cannot be treated as a separate rate class, which means these customers cannot be hit with higher fees for investing in distributed energy.
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When roof top solar reaches 10% penetration, customers will receive 80% of the net.

 

I think you present a pretty dim, unrealistic view of solar power and its risks that are not reflected by reality. Sure, what you say can happen, but most likely won't; not in environmentally friendly California. NEM is grandfathered for existing solar users by the PUC. The sky isn't falling and solar is a good investment in California if you have high power bills.

 

Most people have considerable control over what fraction of personal PV is net metered*, and that fraction will grow as appliance level TOU control becomes common-place. As for "excess electrons," please be more concise.

*As one example, we currently charge our Prius Prime during the day and our LEAF during the night. The night charging is timed to help my CO-OP reduce its demand charges and reduce load on our neighborhood transformer but nothing prevents me from charging during the days when my Prime is not charging.

 

I signed a contract to install 6.5kw panels at the end of the month. It should generate more than 10k kWh per year. It should cover all usage including the Prius. Hopefully should I buy a Tesla in future it would still cover most usage. It is Panasonic panel and price is $2.13/w after tax credit. That's the lowest I got among 4 5 quotes.

 

That’s a great price. Here in Utah , I’m getting quotes anywhere from $3/w to $3.5/w for a 6.5kw install after tax credit.