Hello From Sunny Florida

[bcroe]

what is even more important they will pay you for excess below your cost of production so any excess
becomes negative revenue generator. The bigger excess the worse it looks. Your cost even DIY is
$15,000 / 15,000 kWh / 10 years = 10 c/kWh if it lasts 15 years it would drop to 6 c/kWh but Pocos
typically pay < 4 c/kWh for excess.

I am having a hard time thinking of that as negative revenue. The plant was expensive, but now paid for.
Cost of generation is near zero. In my case they pay me zero for excess; I don't care because I paid zero
for it. The local problem is that the harshness of winters varies so greatly. I am equipped to deal with the
coldest, which leaves quite a surplus after a mild one. Bruce Roe

[J.P.M.]

That is why you know exactly what you are getting into when you sign the contract with the POCO. A true Net Metering contract will pay you the same amount per kWh that the POCO charges you.

Just be careful because your "cost" may include the generation, distribution, fuel and grid maintenance values but their payment may only include the generation and fuel. Distribution and maintenance costs per kWh may not be given to your for your generation.

As in, you gotta' do yur' homework, and really understand what you're getting into.

[SunEagle]

what is even more important they will pay you for excess below your cost of production so any excess becomes negative revenue generator. The bigger excess the worse it looks. Your cost even DIY is $15,000 / 15,000 kWh / 10 years = 10 c/kWh if it lasts 15 years it would drop to 6 c/kWh but Pocos typically pay < 4 c/kWh for excess.

That is why you know exactly what you are getting into when you sign the contract with the POCO. A true Net Metering contract will pay you the same amount per kWh that the POCO charges you.

Just be careful because your "cost" may include the generation, distribution, fuel and grid maintenance values but their payment may only include the generation and fuel. Distribution and maintenance costs per kWh may not be given to your for your generation.

[J.P.M.]

what is even more important they will pay you for excess below your cost of production so any excess becomes negative revenue generator. The bigger excess the worse it looks. Your cost even DIY is $15,000 / 15,000 kWh / 10 years = 10 c/kWh if it lasts 15 years it would drop to 6 c/kWh but Pocos typically pay < 4 c/kWh for excess.

Probably more important still, the best way around overgenerating is to not oversize in the first place. As long as the reimbursement for overgeneration is < the NEM credit, overgeneration will always hurt the bottom line and always hurt the ROI/cost effectiveness. And, system size, because it's an easily controlled parameter, makes oversizing a self inflicted injury. One of the reasons why better information about system capabilities and utility billing methods, both now and into the future is important.

[max2k]

I think JPM is talking about is how pvwatts calculates the $ savings based on some type of $/kWh input. Those number may be skewed so first determine the kWh savings and then run your own calculation of $ savings based on a realistic cost per kWh. Remember whatever is generated above your usage will be sold to the POCO but they may pay you a lower $/kWh that what they charge you.

what is even more important they will pay you for excess below your cost of production so any excess becomes negative revenue generator. The bigger excess the worse it looks. Your cost even DIY is $15,000 / 15,000 kWh / 10 years = 10 c/kWh if it lasts 15 years it would drop to 6 c/kWh but Pocos typically pay < 4 c/kWh for excess.

[J.P.M.]

So are you saying the numbers I'm getting from pvwatts should be higher or lower?

One or the other.

The production numbers are estimates of long term average system output. Actual annual (or 12 month, or running 365 day) output will be different than PVWatts estimate.

That portion of the model seems to do a fair job if the input is reasonably correct. GIGO applies.

What I was referring to is what PVWatts calls "Energy Value". Read the help/info screens for details. My experience is that those $$ estimates of how much the modeled system will save per year are way off. Since most folks do PV to lower electric bills, having reasonably accurate cost saving estimates are kind of important. My opinion based on experience with what PVWatts thinks my POCO is doing as well as looking through the NREL utility rate data gives me the opinion that the data is unreliable as cost data or system design.

[SunEagle]

So are you saying the numbers I'm getting from pvwatts should be higher or lower?

I think JPM is talking about is how pvwatts calculates the $ savings based on some type of $/kWh input. Those number may be skewed so first determine the kWh savings and then run your own calculation of $ savings based on a realistic cost per kWh. Remember whatever is generated above your usage will be sold to the POCO but they may pay you a lower $/kWh that what they charge you.

[max2k]

So are you saying the numbers I'm getting from pvwatts should be higher or lower?

Dollar amounts could be seriously off due to differences how your POCO counts beans and how PVWatts does it.

[CessnaTPA]

If you are one who looks before leaping, then be skeptical of the savings PVWatts is showing. Suit yourself. Production estimates are one thing, but after seeing what PVWatts estimates for $$ savings for users in my POCO, and thinking I know something of my POCO and how their rates work, and also seeing where PVWatts gets its $$ savings figures, I don't trust the PVWatts $$ figures. If you're serious, get and do your own details of how you're charged, and check your calc methods by backing into your current bills - to the penny. Then, while you're at it, snoop around and look for any published, reliable info about how utility rates for your POCO will be changing in both the long and short term, because they will be changing, and those changes will affect the cost effectiveness of any system you acquire, probably negatively. As long as you're not one to leap into something without thoroughly researching it first.......

So are you saying the numbers I'm getting from pvwatts should be higher or lower?

[J.P.M.]

Thanks guys for the good info and advise.
After doing more research and using the PV watts calculator it says with a 10kw system I'd save $1479 a year. Looking online it appears a 10kw system would cost around $15k minus the 30% tax break $10,500, so about 7 years to pay for itself.

I will need to verify if Tampa Electric allows a home owner to DIY. It's definitely a no go if I have to hire someone to do the install.
I feel confident I can do all the work myself since I'm an licensed electrician. And I enjoy doing home improvement projects like this.

I will admit my enthusiasm has dropped a few notches since seeing more realistic numbers with the PV watts calculator. I've never been one to leap into something without thoroughly researching it first. I'll make some phone calls next week and see if I want to proceed. Thanks again.

If you are one who looks before leaping, then be skeptical of the savings PVWatts is showing. Suit yourself. Production estimates are one thing, but after seeing what PVWatts estimates for $$ savings for users in my POCO, and thinking I know something of my POCO and how their rates work, and also seeing where PVWatts gets its $$ savings figures, I don't trust the PVWatts $$ figures. If you're serious, get and do your own details of how you're charged, and check your calc methods by backing into your current bills - to the penny. Then, while you're at it, snoop around and look for any published, reliable info about how utility rates for your POCO will be changing in both the long and short term, because they will be changing, and those changes will affect the cost effectiveness of any system you acquire, probably negatively. As long as you're not one to leap into something without thoroughly researching it first.......

[CessnaTPA]

Sounds like you have a plan. Let us know what TECO allows you to do on the installation.

Where I am now, Duke would not allow me to do anything which made it expensive and very hard to justify an installation. But maybe my new POCO, Withlacoochee Electric will allow me more flexibility on installs next year.

I'm with you it's going to be hard to justify doing solar if I have to hire a contractor. I did get a quote and they wanted $34k for a 13kw and $24k 10kw system. My poco rate is $ .0854 kWh first 1000 kWh and $ .106 above 1000 Kwh's
My nephew was a linesman for Withlacoochee electric.

I'll report back what I find.

[CessnaTPA]

Where did you find a complete roof mounted 10 kw system, including the Solar Panels, Inverter(s), Combiner Box, AC Disconnect, Complete Roof Mount, Conduit, AC Wire, DC Wire, Ground Lugs, Ground Wire and Ground Rod for $15,000 ?

Here is one example for $12300, I rounded up to $15k for shipping and the other electrical supplies that would be needed. Is this not a realistic number?

http://www.freecleansolar.com/10kW-Solar-Kit-Phono-260-SMA-Inverter-Rooftop-p/ps260p-10kw-phono-sma.htm

[SunEagle]

Thanks guys for the good info and advise.
After doing more research and using the PV watts calculator it says with a 10kw system I'd save $1479 a year. Looking online it appears a 10kw system would cost around $15k minus the 30% tax break $10,500, so about 7 years to pay for itself.

I will need to verify if Tampa Electric allows a home owner to DIY. It's definitely a no go if I have to hire someone to do the install.
I feel confident I can do all the work myself since I'm an licensed electrician. And I enjoy doing home improvement projects like this.

I will admit my enthusiasm has dropped a few notches since seeing more realistic numbers with the PV watts calculator. I've never been one to leap into something without thoroughly researching it first. I'll make some phone calls next week and see if I want to proceed. Thanks again.

Sounds like you have a plan. Let us know what TECO allows you to do on the installation.

Where I am now, Duke would not allow me to do anything which made it expensive and very hard to justify an installation. But maybe my new POCO, Withlacoochee Electric will allow me more flexibility on installs next year.

[NEOH]

Thanks guys for the good info and advise.
After doing more research and using the PV watts calculator it says with a 10kw system I'd save $1479 a year. Looking online it appears a 10kw system would cost around $15k minus the 30% tax break $10,500, so about 7 years to pay for itself.

Where did you find a complete roof mounted 10 kw system, including the Solar Panels, Inverter(s), Combiner Box, AC Disconnect, Complete Roof Mount, Conduit, AC Wire, DC Wire, Ground Lugs, Ground Wire and Ground Rod for $15,000 ?

[CessnaTPA]

Thanks guys for the good info and advise.
After doing more research and using the PV watts calculator it says with a 10kw system I'd save $1479 a year. Looking online it appears a 10kw system would cost around $15k minus the 30% tax break $10,500, so about 7 years to pay for itself.

I will need to verify if Tampa Electric allows a home owner to DIY. It's definitely a no go if I have to hire someone to do the install.
I feel confident I can do all the work myself since I'm an licensed electrician. And I enjoy doing home improvement projects like this.

I will admit my enthusiasm has dropped a few notches since seeing more realistic numbers with the PV watts calculator. I've never been one to leap into something without thoroughly researching it first. I'll make some phone calls next week and see if I want to proceed. Thanks again.