Grid-tied solar

[Redneck in training]

Yes and No. To see the fancy stuff you have to be on Internet. I can connect dirrectly to the Envoy but that is text only.

 

[dave1949]

The December results.

This month was below the model, for the first time. We had a lot storms move through and extended cloudy periods.

My net usage was 492.2 KWH of which the system produced 297.2 KWH. I went from having 75 kWh banked to 120 kWh in the hole. Net usage was 87 kWh higher than Dec. 2011, most of which would be due to having an electric water heater now. Also had to run an electric space heater in the bedroom for four nights toward the end of the month due to a lack of solar heating. That is not unusual around the end of the year.

A good production day now is 20-21 kWh. The sun gets up above the tree horizon around 9:30 am and goes behind the hill to our West about 3:45 pm. Now that we are beyond the Winter Solstice, production should start picking up. The 10-day forecast has a lot of sun in it, cold, but sunny.

The PVWatts model AC kWh predicted/actual:
Aug. 383/460.7
Sep. 394/480.9
Oct. 369/378.6
Nov. 283/400.3
Dec. 331/297.2
Jan. 388/TBD
Feb. 412/TBD
Mar. 509/TBD
Apr. 374/TBD
May 353/TBD
Jun. 308/TBD
Jul. 341/TBD

 

[Redneck in training]

We put first bank of panels on line last week of November and completed our PV system sometime in second week in December. It produced 1700 kWh so far. We have net metering but not banking so we have to settle the account every month. We get paid 3.5 cent/kWh for the excess but we can keep our heating rate during the heating season. My calculation based on last year consumption data predicted that we should be about $180 in black over one year period.

 

[dave1949]

The January, 2013 results.

This month was above the model. We had several really good stretches of sunny days this month.

My net usage was 482 KWH of which the system produced 440 KWH.

We had a couple of 25 Kwh AC production days, and some 0.2 Kwh days too. :laughing: The sub-zero lows during the cold spell caused us to turn on the bedroom electric space heaters three or four nights, and I had the 75W bulb on in the well pressure tank room for a week.

The PVWatts model AC kWh predicted/actual:
2012
Aug. 383/460.7
Sep. 394/480.9
Oct. 369/378.6
Nov. 283/400.3
Dec. 331/297.2
2013
Jan. 388/440
Feb. 412/TBD
Mar. 509/TBD
Apr. 374/TBD
May 353/TBD
Jun. 308/TBD
Jul. 341/TBD

 

[Redneck in training]

We completed our system in first half of December. Total capacity is 24kW DC. PVWatts predicted (for January) 2388 kWh/ system produced 2570 kWh. Needles to say that the efficiency coefficient is not calibrated yet. I am waiting for first electric bill for full month with new net metering meter that meters separatelly energy pushed to/ received from the grid to calculate the coeffcient with better precission. I used efficiency coeffifient 0.85 based on reported efficiency of the inverters and current and voltage drop over the cable between the arrays and the power meter.

 

[dave1949]

We completed our system in first half of December. Total capacity is 24kW DC. PVWatts predicted (for January) 2388 kWh/ system produced 2570 kWh. Needles to say that the efficiency coefficient is not calibrated yet. I am waiting for first electric bill for full month with new net metering meter that meters separatelly energy pushed to/ received from the grid to calculate the coeffcient with better precission. I used efficiency coeffifient 0.85 based on reported efficiency of the inverters and current and voltage drop over the cable between the arrays and the power meter.

Our system is rated at 4.2 KW, our inverter is a 4 KW model. On the really clear sunny days, the panels are exceeding the inverter capacity for 2-3 hours around mid-day, which causes the inverter to go into "derate" mode. During "derate" the inverter keeps running but limits the power throughput to what it can handle.

A 5 KW inverter would cost a good bit more, so the trade-off of losing a few Kwh's this time of year is acceptable. We didn't see any derating when the sun angle was higher, and less optimal for our panel mounting angle.

Anyways, based on that observation, the panel output ratings are not over-stated. They can easily produce their rated output. We'll see how that holds up as they age.

 

[Redneck in training]

Our system is rated at 4.2 KW, our inverter is a 4 KW model. On the really clear sunny days, the panels are exceeding the inverter capacity for 2-3 hours around mid-day, which causes the inverter to go into "derate" mode. During "derate" the inverter keeps running but limits the power throughput to what it can handle.

A 5 KW inverter would cost a good bit more, so the trade-off of losing a few Kwh's this time of year is acceptable. We didn't see any derating when the sun angle was higher, and less optimal for our panel mounting angle.

Anyways, based on that observation, the panel output ratings are not over-stated. They can easily produce their rated output. We'll see how that holds up as they age.

Our system is large because we heat two buildings with electric heat pumps. House has geothermal and the shop has air/air but is heated (when unoccupied) to 40F. We should get January bill sometime next week. I am hoping that there will be enough information to determine actual efficiency.

 

[dave1949]

The February, 2013 results.

This month was below the model. Missed it by less than two sunny days. At mid-month, it was on-track to meet or exceed the model. Too many storms rolling through the second half of the month.

My net usage was 466 kWh of which the system produced 375 kWh.

The PVWatts model AC kWh predicted/actual:
2012
Aug. 383/460.7
Sep. 394/480.9
Oct. 369/378.6
Nov. 283/400.3
Dec. 331/297.2
2013
Jan. 388/440
Feb. 412/375
Mar. 509/TBD
Apr. 374/TBD
May 353/TBD
Jun. 308/TBD
Jul. 341/TBD

 

[Redneck in training]

Our system also didn't make the predicted production.
predicted 2.78 MWh/actual 2.3 MWh

 

[dmccarty]

The latest issue of Journal of Light Construction had an article about installing solar power panels. The contractor was in Mass and said that the installation cost was $4.30 per watt. The price seems to be dropping steadily.

Later,
Dan

 

[Redneck in training]

The latest issue of Journal of Light Construction had an article about installing solar power panels. The contractor was in Mass and said that the installation cost was $4.30 per watt. The price seems to be dropping steadily.

Later,
Dan

I got a quote in Iowa for 3.90/W turn key before tax rebate. I did it DIY last year for 2.25/W. Or 1.46/W after tax rebate. Our system is ground mounted and uses microinverters. If you can mount it on a roof and use single large inverter you can save at least 10 to 15% of the cost before tax rebate.

 

[Dr Dave]

I was told, if you put solar on your home and replace the roof with a metal roof at the same time, then the roof would also be eligable for the rebate?


Dave

 

[dmccarty]

I got a quote in Iowa for 3.90/W turn key before tax rebate. I did it DIY last year for 2.25/W. Or 1.46/W after tax rebate. Our system is ground mounted and uses microinverters. If you can mount it on a roof and use single large inverter you can save at least 10 to 15% of the cost before tax rebate.

The article I mentioned use microinverters. I designed our roof to be at the optimum roof angle for solar gain. Kinda got lucky in that angle matched some other design criteria! :laughing::laughing::laughing:

The last time I look at the NC rules, for us to get the NC subsidy, the system has to be installed by a "professional", it cannot be done by a DIY selfer. We can get at least 5,000 watts on the roof and maybe 10,000 watts. 10K watts would cover close to 100% of our power usage over the year.

Later,
Dan

 

[Redneck in training]

The article I mentioned use microinverters. I designed our roof to be at the optimum roof angle for solar gain. Kinda got lucky in that angle matched some other design criteria! :laughing::laughing::laughing:

The last time I look at the NC rules, for us to get the NC subsidy, the system has to be installed by a "professional", it cannot be done by a DIY selfer. We can get at least 5,000 watts on the roof and maybe 10,000 watts. 10K watts would cover close to 100% of our power usage over the year.

Later,
Dan

Dan,
You can get yourself certified. Or you can do most of the mechanical stuff by yourself, install all the hardware and then let them to connect it all together. There is no wiring (or very little) involved with the microinverters. You get a special cable and plug it all in. I
If you decide to do it have interconnection agreement signed before you purchase the hardware and base your ROI on that. I asked for interconnection agreement. The Coop sent me paper that described net metering with banking. But I had to leave for business trip and didn't sign it. When I built my system they back pedaled and said that they changed the policy. So I am selling my power during the day for 3.5 c and buying it back at night for 11.5. I was hoping to have zero electric bill but it dropped only to about half in the winter and will drop even more in the spring and summer. It will take much longer to pay for itself now. I plan to go to board of directors meeting plead my case. If you are on state regulated utility the state sets the policies.

 

[dave1949]

I was told, if you put solar on your home and replace the roof with a metal roof at the same time, then the roof would also be eligable for the rebate?
Dave

IRS Form 5695 is where the various energy credits are allowed. Some metal roofs may qualify for an energy efficiency credit, but I don't know about combining it with a solar credit. Probably best to look at that form and read the instructions for it on-line at the irs.gov site.

 

[dmccarty]

Dan,
You can get yourself certified. Or you can do most of the mechanical stuff by yourself, install all the hardware and then let them to connect it all together. There is no wiring (or very little) involved with the microinverters. You get a special cable and plug it all in. I
...

I am not sure I can in NC. I remember reading years ago about the requirements and there was no way I could meet them. I just went and did some reading but I can't find the requirements. Maybe the law/rules have changed or it is buried in the tax code. In any case, I certainly would have to have an electrician make the connections to the grid, but that would not cost much. The article in JLC certainly seemed easy. I did not like some of the things they were doing on the roof and I would have done it differently. The PV install looked pretty danged easy.

Interestingly, I got an email this morning about a PV class at our community college for home owners that went over all of this stuff. Too bad I have a conflict or I might have taken the class.

NC appears to now have net metering with retail rates at least that is how I interpreted what I read. Before I thought excess power was bought at wholesale rate. There are also subsidies from the power company that works out to $1.02 per watt which is not bad. NC pays 35% and the Fed another 30%. Looks like out out of pocket would be greatly reduced at $4 a watt but we still have to have the money upfront and we don't. The NC subsidy can take five years to be fully paid off. At the moment I have a tax situation that makes me wonder if I would ever get the NC subsidy...

Anyway, at the rate the PV costs are falling I think it is better to wait. Seems like last year when I was looking at PV costs it was around $7 per watt.

Later,
Dan

 

[Redneck in training]

I am not sure I can in NC. I remember reading years ago about the requirements and there was no way I could meet them. I just went and did some reading but I can't find the requirements. Maybe the law/rules have changed or it is buried in the tax code. In any case, I certainly would have to have an electrician make the connections to the grid, but that would not cost much. The article in JLC certainly seemed easy. I did not like some of the things they were doing on the roof and I would have done it differently. The PV install looked pretty danged easy.

Interestingly, I got an email this morning about a PV class at our community college for home owners that went over all of this stuff. Too bad I have a conflict or I might have taken the class.

NC appears to now have net metering with retail rates at least that is how I interpreted what I read. Before I thought excess power was bought at wholesale rate. There are also subsidies from the power company that works out to $1.02 per watt which is not bad. NC pays 35% and the Fed another 30%. Looks like out out of pocket would be greatly reduced at $4 a watt but we still have to have the money upfront and we don't. The NC subsidy can take five years to be fully paid off. At the moment I have a tax situation that makes me wonder if I would ever get the NC subsidy...

Anyway, at the rate the PV costs are falling I think it is better to wait. Seems like last year when I was looking at PV costs it was around $7 per watt.

Later,
Dan

Dan,
PV panels were about 3.50/W in 2011 and dropped to below 1/W in 2012. If the cost stays that low is a question though. Several large purchasers of the PV panels such as Germany, Spain, Italy and I think also Australia cancelled the subsidy in 2012. In the same time China put on line the largest silicon wafer plant on the world. So there was a glut of the PV panels on the world market. Well that is the story I heard.
We financed the system by a home equity loan. I figured that at current interest rates it made a sense because the interest (in addition to being low) is also tax deductible.
If you have new metering that DIY system will pay for itself in about 6-7 years.
I got my stuff at Civic Solar.
CivicSolar | Solar Panels - Photovoltaic Cells - Solar Power - Inverter - Charge Controller - Battery
I paid $225 for 250 W Canadian Solar panels, 135 for 215 W Enphase microinverter, 23 per a section of Enphase cable and estimated another 180 for associated hardware such as solar rails, wood, concrete, bolts, breaker boxes, disconnect and 500 ft of cable to transformer etc. That is about 2.25/W or $562/panel installed on ground before tax rebate.

 

[dmccarty]

Dan,
PV panels were about 3.50/W in 2011 and dropped to below 1/W in 2012. If the cost stays that low is a question though. Several large purchasers of the PV panels such as Germany, Spain, Italy and I think also Australia cancelled the subsidy in 2012. In the same time China put on line the largest silicon wafer plant on the world. So there was a glut of the PV panels on the world market. Well that is the story I heard.
We financed the system by a home equity loan. I figured that at current interest rates it made a sense because the interest (in addition to being low) is also tax deductible.
If you have new metering that DIY system will pay for itself in about 6-7 years.
I got my stuff at Civic Solar.
CivicSolar | Solar Panels - Photovoltaic Cells - Solar Power - Inverter - Charge Controller - Battery
I paid $225 for 250 W Canadian Solar panels, 135 for 215 W Enphase microinverter, 23 per a section of Enphase cable and estimated another 180 for associated hardware such as solar rails, wood, concrete, bolts, breaker boxes, disconnect and 500 ft of cable to transformer etc. That is about 2.25/W or $562/panel installed on ground before tax rebate.

I had not read that the PV cost had finally dropped to $1/watt. I have read that the price drop is because of over supply from China and lack of demand. Demand has dropped because the subsidies have dropped.

We don't have any way to pay for PV at the moment. I do think the time is likely the best time to install. The price has dropped and I don't know how much farther it can drop if the price is at $1/watt. The price is likely near the bottom which makes it a good time to buy before the US subsidies end.

Your prices are danged interesting. If, and I think it is a big if, I could get a system installed at $2.25 a watt that would be real interesting. I think our roof can handle 10,000 watts. Why 10K watts, well the number makes the math easier and that would provide close to 100% of our power. Maybe a bit of surplus.

10K watts x $2.25 = $22,500.
NC and Fed subsidy is 65% which leaves $7,875.

The local power company has or had a subsidy that works out to a $1 a watt which in this case would be $10,000!

The key is can I get an installed systems for $2.25 a watt?
Does the power company still have that $1 per watt program?

Oh, where do I get $22K? :shocked::laughing::laughing::laughing:

Our current tax situation is such that we might not be able to get the full subsidy from the state so that numbers do not look as good as one would think.

Later,
Dan

 

[EE_Bota]

I think it's time for Dan to pull out some of that crusty old money and grab some solar.

 

[dmccarty]

I think it's time for Dan to pull out some of that crusty old money and grab some solar.

I will take new, neat money, old crusty money, or anything in between! I checked under my pillow and there was nothing to be found. :shocked::laughing::laughing::laughing:

I mentioned a solar class at the local CC earlier in the thread. I sent them a note about the course, which starts Saturday, to see if they have an opening. The course description is not as descriptive as I would like but if they have an opening I will take the class. It is only two hours for three Saturdays. I thought I had a conflict but the conflict is on a Sunday.

Ya'll can send me crusty dollars as long as they are legal tender in the US!

Later,
Dan