I'm considering having a solar panel electrical system installed.

[dynasim]

RobD,

They are your assumptions, you do the math. After all, you are an engineer.

Every material good consist of labor and energy. In the end, they are the only 2 inputs to produce anything.

Chris

 

[Rob-D]

I e-mailed my state DOE about some incentives and stuff, and they linked me to that site as well.

According to it, with my 11cent per kwh rate, a 5kw rated system is only going to save me $619/year. And at ~$15k to install ($3/watt) payback is going to be well over 20 years

And thats probabally a pretty realistic figure. They break it down by month. And according to Rob-d's chart, it appears his 6.4kw system is on pace to do 600-700kwh this month. And the pvwatts site lists a 5kw system producing 507kwh for march. So thats probabally pretty close to real world #'s.

Not sure how much location changes it, but If I use a 6.4kw system like rob's, it is showing 648kwh for march.

Glad I found that site with some realistic #'s. Because a novice like me is looking at a 5kw system and thinking it "should" be capable of ~1500kwh or so a month. thats 5kwh x 10hrs/day x 30 days. Obviously in optimal conditions. I didnt realize the inefficiencies were that high. Cause pvwatts says in the peak summer months, a 5kwh system is only making 633kwh.

Even if my electric coop did net metering, I doubt it would matter much on a system that small. and at $15k, even if I take 30% off for the credit, I am still looking at 10k+. And that is still almost a 20 year payback time.

It just isnt there for me yet.

That's a very low rate, most rates in this country run between 12 and 50 cents a KWH. Is that your total rate or do you have to add on other taxes, etc. to get your final figure?

My electric rates are 9.219 cents a KWH but there is monthly fee the coop charges its patrons of $15.25 and cost adjustment factor of 1.2 cents a KWH which I believe goes up if you use over a specific KWH level.

So if I use 500 KWH's a month the final bill is 9.219x500+1.2x500+15.25=$67.35=13.47 cents a KWH. We have some of the lowest rate you can get, NYSEG (New York State Elec & Gas) that services the village charges roughly 3 times that and commercial rates are even higher. This is with rates not changing in the nest 20 years which is highly unlikely.
You may be right, at today's rates it may not be cost effective for you to install a PV system but I think an average KWH rate is closer to 20 to 25 cents. A lot of the people on TBN live rurally (people on a 1/4 acre aren't buying tractors for the most part) and rural rates are usually lower, like mine compared to the village.

A 25 cent KWH would pay off, again if rates don't go up, much faster than your calculations.

I'm now talking to a farmer who is on commercial NYSEG and paying very high rates, I think they are double or triple residential rates. He's concerned that the constantly rising rates will ruin him.

The bottom line is that the gap is closing, PV is dropping and electric costs are rising. Now add the benefit that you reduce the rates of everyone in the coop, the grid gets stronger and the environment gets cleaner and we're not subsidizing terrorists and the picture changes.

Rob

 

[Rob-D]

RobD,

They are your assumptions, you do the math. After all, you are an engineer.

Every material good consist of labor and energy. In the end, they are the only 2 inputs to produce anything.

Chris

You made the statements defend them! I didn't make an assumption, I quoted a valid article, not from a socialist group, but International Rectifier a large producer of semiconductors.

This is a thread about an inquiry into installing a PV system. Are you interested in that? Or are you just trolling and looking to make remarks about socialism?

And by the way war is a form of socialism.

Again, do you have a system, have you ever installed a system? Do you have expertise in the area?

Rob

 

[Rob-D]

Here are a few shots of what I put in.

Also keep in mind you also make money selling renewable energy credits.

paul

Nice system Paul.
Did you find it cheaper to install ground mount as opposed to pole mounting the panels?
Whose mounting system did you use?

Rob

 

[dmccarty]

And thats probabally a pretty realistic figure. They break it down by month. And according to Rob-d's chart, it appears his 6.4kw system is on pace to do 600-700kwh this month. And the pvwatts site lists a 5kw system producing 507kwh for march. So thats probabally pretty close to real world #'s.

Not sure how much location changes it, but If I use a 6.4kw system like rob's, it is showing 648kwh for march.

Glad I found that site with some realistic #'s. Because a novice like me is looking at a 5kw system and thinking it "should" be capable of ~1500kwh or so a month. thats 5kwh x 10hrs/day x 30 days. Obviously in optimal conditions. I didnt realize the inefficiencies were that high. Cause pvwatts says in the peak summer months, a 5kwh system is only making 633kwh.

The problem with you expectation of power production is likely the number of power producing hours per day. 10 hours a day is most likely the difference in your numbers and the website.

About half way down on this link is a list of US cities and the number of power producing hours available in the summer and winter, Six Steps To Sizing A PV System

I designed a house that is passive solar, has a nice expanse of roof with a great southern exposure and with the optimum angle to the sun for solar power production. In my area, I can only expect about five hours of solar power production a day with a roof with a full southern exposure at the optimum angle.

I am lucky in that our area gets 5ish hours of useful sun time year round. Other areas have more sun time in the summer but much less in the winter or vice versa. This could also be affecting the numbers you expected vs what the online calculator showed.

Another thing to consider is that if you hot water is heated by electric power, you really should put up a solar hot water panel to heat water and not use PV power to heat the water. I figure heating water is about 20-30% of our power bill.

I am still shocked at the loss of power from the panels to the outlets. Home Power magazine mentioned a 35% loss.

And according to Rob-d's chart, it appears his 6.4kw system is on pace to do 600-700kwh this month.

6.4 KW * 5 hours of sun a day = 32 KHW per day.
32 KWH per day *30 days = 960 KWH per month.
960 KWH * .65 usable power = 624 KWH per month.

32 KWH per day * .65 = 20.8 KWH a day.

For those with PV systems, are you seeing a 35% loss of power from the rated power production on the panels?

People keep mentioning DIY installations. To qualify for the NC subsidy the system must be installed by a "professional" whatever that means. Progress Energy, our power provider, also has some programs that offer PV subsidies but the system has to be installed by the "professional. So check the rules for your location. With the exceptions of the electrical tie the install looks pretty simple to me. I could see the savings for the DIY might negate the need for the tax subsidy.

Later,
Dan

 

[techman]

Nice system Paul.
Did you find it cheaper to install ground mount as opposed to pole mounting the panels?
Whose mounting system did you use?

Rob

I did not consider pole mount, since I did not have the equipment to put in the 9' deep footers required. The rack is a Schletter PV Max. 40 Bosch 230 watt panels and a Fronius 10KW inverter. The rack is about 125' from the house. Near the house is too shaded by trees, and the roof is too small and also shaded. Construction/install took longer than expected, mostly due to permitting and other paperwork delays, and also a very wet summer/fall last year. I finally powered up the end of September. So far 5.2 MWH

paul

 

[Rob-D]

The problem with you expectation of power production is likely the number of power producing hours per day. 10 hours a day is most likely the difference in your numbers and the website.

About half way down on this link is a list of US cities and the number of power producing hours available in the summer and winter, Six Steps To Sizing A PV System

I designed a house that is passive solar, has a nice expanse of roof with a great southern exposure and with the optimum angle to the sun for solar power production. In my area, I can only expect about five hours of solar power production a day with a roof with a full southern exposure at the optimum angle.

I am lucky in that our area gets 5ish hours of useful sun time year round. Other areas have more sun time in the summer but much less in the winter or vice versa. This could also be affecting the numbers you expected vs what the online calculator showed.

Another thing to consider is that if you hot water is heated by electric power, you really should put up a solar hot water panel to heat water and not use PV power to heat the water. I figure heating water is about 20-30% of our power bill.

I am still shocked at the loss of power from the panels to the outlets. Home Power magazine mentioned a 35% loss.



6.4 KW * 5 hours of sun a day = 32 KHW per day.
32 KWH per day *30 days = 960 KWH per month.
960 KWH * .65 usable power = 624 KWH per month.

32 KWH per day * .65 = 20.8 KWH a day.

For those with PV systems, are you seeing a 35% loss of power from the rated power production on the panels?

People keep mentioning DIY installations. To qualify for the NC subsidy the system must be installed by a "professional" whatever that means. Progress Energy, our power provider, also has some programs that offer PV subsidies but the system has to be installed by the "professional. So check the rules for your location. With the exceptions of the electrical tie the install looks pretty simple to me. I could see the savings for the DIY might negate the need for the tax subsidy.

Later,
Dan

Dan,
That's the benefit of microinverters. I have to go check the efficiency of my total system but it's very high. For starters I think the microinverters are 97 or 98%.
I have two meters, one between the main PV output and one on the pole the co-op monitors. When I put the system in I checked them both often but now not so much. I know it's not 35% though. Your figures above aren't taking everything into account, my east/west loss for instance.

Rob

 

[techman]

Dan,
That's the benefit of microinverters. I have to go check the efficiency of my total system but it's very high. For starters I think the microinverters are 97 or 98%.
I have two meters, one between the main PV output and one on the pole the co-op monitors. When I put the system in I checked them both often but now not so much. I know it's not 35% though. Your figures above aren't taking everything into account, my east/west loss for instance.

Rob

Rob:

I see about 32% reduction. Weather, even haze will lower the output. Remember that the panel ratings is based on maximum solar energy of 1000w/m^2, which does not exist in most places, unless you live on the equator. Add temperature effects (hotter means less output), wiring and inverter efficiencies and the losses add up. My biggest factor is weather. Microinverters MAY help, but primarily where part of the array may be shaded. Otherwise the single, central inverter does as well. Also microinverters are relatively new and do not have as clean track record as far as reliability as some conventional inverters have.

PVWATTS gives a very good estimate of power capacity. In my case I am within 5% so far.

paul

 

[techman]

Here you can see how the output can vary from day to day due to weather. November was relatively good, while January was not quite as good. I would love to have full sun for 5 hours a day, 30 days a month !

paul

 

[LD1]

That's a very low rate, most rates in this country run between 12 and 50 cents a KWH. Is that your total rate or do you have to add on other taxes, etc. to get your final figure?

Yes that is my TOTAL rate. It works out the more you use, the less it is per kwh too. But my TOTAL rate averages 11 cents right now. That is the TOTAL of my bill/kwh usage. My last bill was 2396kwh usage and $251. That is about 10.5 cents. And up until about a year and a half ago, it was consistantally 8 cents. Than around november 2010, it started creaping up over about 6 months to the ~11 cents I am at now. And it has remained pretty stable for the last year. I track everything on an excel spreadsheet. For 2010, total yearly usage was 23,607 kwh and 2011 was 23,128.

Dan,
That's the benefit of microinverters. I have to go check the efficiency of my total system but it's very high. For starters I think the microinverters are 97 or 98%.
I have two meters, one between the main PV output and one on the pole the co-op monitors. When I put the system in I checked them both often but now not so much. I know it's not 35% though. Your figures above aren't taking everything into account, my east/west loss for instance.

Rob

Even as efficient as those inverters are, look at the WHOLE. You say you have a 6.4kwh system and are on pace to do ~700kwh this month.

We have a little over 12 hrs from sunrise to sunset in march. Using my mentioned 10 hours, and 30 days/month, that would be 1920kwh. Even only using half of the 12 hrs (6 hours) a day, should land you in the 1150 kwh range, yet you come in at ~700kwh.

Now I know that the first few hours and last few do little. I understand that. And understand that mid-day is optimal. I am not trying to dis-credit anything here. Just mearly pointing out how difficult it is to figure these things when you look at a system that is "rated" for X.X kwh, it is hard to correlate that to REAL WORLD numbers. With your system and sharing the info, we are better able to get a REAL Idea of what the production is going to be. Now we know it takes a 6.4kwh system to produce ~700kwh in march and probabally ~1000kwh or so in the summer.:thumbsup:

Knowing stuff like that makes us better able to calculate cost of payback more accuratly than trying to use what the pannels are "rated" at.:thumbsup:

And for me, without net-metering and lower utility rates, COP is still 20+ years and not a viable option at the moment for me.