PV Calculator

[Len]

Does anyone have a good solar pv payback calculator????

 

[K8MHZ]

Does anyone have a good solar pv payback calculator????

You mean like a website?

http://mayer.pro/PVcalc

I just do the math. It always comes out to 50 years.

What you are asking for is the ROI, or return of investment. It's not a single formula. Figuring an ROI for a typical residence takes about a page of math if you don't overlook anything. You also have to be able to predict the future by guessing what the cost of energy will be decades from now.

 

[97catintenn]

Or would you like me to save you some time and say, "it doesn't really pay back any real cash" ? :lol:

 

[K8MHZ]

Or would you like me to save you some time and say, "it doesn't really pay back any real cash" ? :lol:

That's kind of where the industry is at right now. Without some sort of government incentives, an ROI that exceeds the life expectancy of the equipment is pretty much the way it is.

 

[jaggedben]

Without some sort of government incentives, an ROI that exceeds the life expectancy of the equipment is pretty much the way it is.

Well, not in California if you are paying Tier 3 or higher rates.

We've had this discussion before. It depends on a lot of factors and it some places it pays back more quickly.

 

[Zee]

Not really a CODE question.
But i use - and like - ONGRID. I met ANdy BLack YEARS ago when he was the first guy talking about this stuff: how to figure out payback.

You gotta pay for it. Like anything worth something.

 

[ejerrym]

The best I've seen is the Energy Periscope software.

http://www.energyperiscope.com/


Very detailed production and financial analysis.

 

[mlnk]

Are you talking about borrowing from a bank or from yourself?
I spent 12k on my solar panel system. I am saving about 1,100 per year in "cash" on my electric bill.
If I borrowed 12K from a bank @ 5% APR, an amortized loan of 16 years would pay the loan back at $91 per month.
If I borrowed from a savings account paying 1%, it would take about 12 years to pay myself back.
If electric rate go up, it would be fewer years pay back. If interest goes up, assume this is an adjustable loan, it would be more years. Also my roof faces due South with no shade and my slope is 26% and I clean my panels every 3 months. One day I monitored cleaning the panels and production went up 20%!

I got a rebate and a tax write off, without this the system would have cost 23k.
Also, PGE pays a bonus rate of 33 cents per kw for Noon to 6 pm production and reduces my other usage to about 9 cents per kw. So I am subsidized again. Also, if I use a lot of power, my rate can go up to as much as 61 cents per kw.
I realize that oil,coal,hydro, nuclear companies get huge government subsidies and tax breaks.

The problem in comparing solar to other investments is called spent capital. If you invest in Apple stock and make 9%, you can sell the stock and get your investment capital back. If you lose 40%, that is another story. In solar you cannot get your capital back, unless you sell your house, then it is debatable.

 

[don_resqcapt19]

... I am saving about 1,100 per year in "cash" on my electric bill.
...

How much power do you use and what was your average bill before solar? I average about 1125 KHW per month and the cost averages $139 per month. I can't see solar ever paying for me.

 

[ggunn]

How much power do you use and what was your average bill before solar? I average about 1125 KHW per month and the cost averages $139 per month. I can't see solar ever paying for me.

Build a smaller system. As long as the system you build produces less energy than you use, the payback time is the same no matter what size it is.

 

[don_resqcapt19]

Build a smaller system. As long as the system you build produces less energy than you use, the payback time is the same no matter what size it is.

Given my costs from the utility, I haven't been convinced that there is a payback within the life of the solar equipment.

 

[ggunn]

Given my costs from the utility, I haven't been convinced that there is a payback within the life of the solar equipment.

Well, of course, if electricity is very cheap for you and you do not anticipate it getting significantly more expensive in the next 20 years or so then solar may not be an economically attractive option for you.

 

[ron]

How much power do you use and what was your average bill before solar? I average about 1125 KHW per month and the cost averages $139 per month. I can't see solar ever paying for me.

Don,
With about a $10k investment, and that you pay about 12.3 cents per kWH, you would generate about $770 worth of electricity with a 5kW DC system rather than buy it from your utility company if your panels followed my calculation assumptions. I knew Illinios, so I guessed a major city to make the calculation below as an example.

Your simple payback would be 13 years. But it is likely your cost per kWH from the utility will grow from 12.3 over time so the payback would be less.

 

[jaggedben]

Don,
With about a $10k investment ... a 5kW DC system

That's a super low cost per watt. He'd have to install it himself , and maybe use the leftover materials from his other jobs. However that's presumably an option to consider for a moderator on this forum.

 

[ron]

That's a super low cost per watt. He'd have to install it himself , and maybe use the leftover materials from his other jobs. However that's presumably an option to consider for a moderator on this forum.

Many solar providers offer PPA type lease "models" for residential where they will own it, maintain it, guarentee a minimum production and collect the SREC's & incentives. Then they charge a relatively low upfront investment, such as $10k. That's what I'm doing.

 

[don_resqcapt19]

... But it is likely your cost per kWH from the utility will grow from 12.3 over time so the payback would be less.

It went down effective 6/1. The cost for just the electricity is now 4.39 cents per kWH, but the transmission, distribution and other charges will bring it upt to about 10 cents.

 

[ron]

It went down effective 6/1. The cost for just the electricity is now 4.39 cents per kWH, but the transmission, distribution and other charges will bring it upt to about 10 cents.

Wow thats a great rate. Do you live next to a waterfall?

 

[Zee]

Don,

Your payback is hugely dependent on whether or not you can benefit from Time-of-use rates!
Do you have those available?

But yeah....with your bills, it is not a get rich quick type of deal to go solar.

Do consider also: saving a buck is worth the same as making a buck 30, if you pay average income tax.

My personal belief:
1. unprecedented inflation is a given in near future.
2. Energy goes first.
In 10 years we will all be laughing at how we used to pay only 10 cents per kwh!

 

[hillbilly1]

It went down effective 6/1. The cost for just the electricity is now 4.39 cents per kWH, but the transmission, distribution and other charges will bring it upt to about 10 cents.

Wow thats a great rate. Do you live next to a waterfall?

That's about what we pay down here, though I am close to about seven hydroelectric plants that have been online since around the 60's or 70's

 

[don_resqcapt19]

Wow thats a great rate. Do you live next to a waterfall?

There is not too much hydro in Illinois. I think the majority of the generation in Illinois in nuclear.