Grid-tied solar

[houstonscott]

Made 693.987 kwhs in June, system started on the 8th of June, so July should beat that easy. A question, how often should the hardware on the racking system be checked and tightened. HS

 

[ultrarunner]

360 kWh is average monthly usage year round for Mom's home... so your array would be enough to power two 2400 square foot 4 bedroom, 2.5 bath homes in her California neighborhood.

 

[Redneck in training]

I've got a building that uses about 18,000 kWh per month. There is a company that wants to sell us a solar system with no storage stating that the local electric corp. (NGrid) will by back the excess. I've checked around and no where can I find that NGrid has to buy anything back. After all the taxes , fees and surcharges, we pay about 23 cents per kw. so our bill is a bit over 4K per month. I am concerned about snow load and how much a system this large will produce during winter months. As I do not feature going onto a roof to shovel off panels, a ground array is almost mandatory. They make a statement that r.o.i is about 5-8 yrs.

We average 98 days out of 365 of pure sunshine and the rest is partly to fully cloudy. Kind of skeptical at this point. Installation cost is 300K so the math is not meshing in my head as they have stated. Right now it seems to me as if it would be more like over 20 years r.o.i.

I asked where they got their output numbers and they say "around here". Well in comparing where say Siberia is, Texas is "around here". They have one other array in RI but it is near the coast where it does not snow as much. I asked to see the billing comparisons for actual savings and they state it is not in their purview to show that systems billing costs. OK, I understand. When contacting the "principals" of that system, they were very enthusiastic and stated they were saving quite a bit of money. I asked for an example but the woman could not give me an actual figure. If it was their first installation in the state, I am wondering if the solar company gave them an incentive to "pitch" their system. I'm not getting straight answers from anyone so I've got red flags going on in my head at this point.

Estimated size of proposed system would be (just guessing) around 155 kW DC so 300,000 installation cost is rather low. If you finance it at current interest rates your loan payment for 10 years loan would be around $3500-4000/month and you get 100000 tax rebate.
Roof installation is about 20-30% cheaper than ground mounted. The panels are black and get warm under the snow so the snow slides down after few hours of sun shine as long as the slope is sufficiently steep.
The utility has to have "Net metering" to make ROI short. The problem might be that for system this large it might not be available. But at 24 cent/kWh it would pay for itself in about 10-12 years even without net metering and it will shield you from future energy cost increases. You can also do a lot of mechanical installation by yourself and save lot of money.

 

[Redneck in training]

Made 693.987 kwhs in June, system started on the 8th of June, so July should beat that easy. A question, how often should the hardware on the racking system be checked and tightened. HS

Give it few month and then go over it. Rap the panel and listen for a rattle. Or listen to it during windy weather. I would recommend to use a torque wrench because of the stainless steel bolts are easy to strip and it is a pain to replace them. I don't know what the required torque is but I went through the pain of replacing few bolts.

How about picture?

 

[dave1949]

I've got a building that uses about 18,000 kWh per month. There is a company that wants to sell us a solar system with no storage stating that the local electric corp. (NGrid) will by back the excess. I've checked around and no where can I find that NGrid has to buy anything back. After all the taxes , fees and surcharges, we pay about 23 cents per kw. so our bill is a bit over 4K per month. I am concerned about snow load and how much a system this large will produce during winter months. As I do not feature going onto a roof to shovel off panels, a ground array is almost mandatory. They make a statement that r.o.i is about 5-8 yrs.

We average 98 days out of 365 of pure sunshine and the rest is partly to fully cloudy. Kind of skeptical at this point. Installation cost is 300K so the math is not meshing in my head as they have stated. Right now it seems to me as if it would be more like over 20 years r.o.i.

I asked where they got their output numbers and they say "around here". Well in comparing where say Siberia is, Texas is "around here". They have one other array in RI but it is near the coast where it does not snow as much. I asked to see the billing comparisons for actual savings and they state it is not in their purview to show that systems billing costs. OK, I understand. When contacting the "principals" of that system, they were very enthusiastic and stated they were saving quite a bit of money. I asked for an example but the woman could not give me an actual figure. If it was their first installation in the state, I am wondering if the solar company gave them an incentive to "pitch" their system. I'm not getting straight answers from anyone so I've got red flags going on in my head at this point.

That all sounds iffy to me. I would shy away from that dealer from what you have said.

Some research on RI's net metering is needed. There are sites like this one:
Rhode Island Net Metering
But I would certainly talk to your utility directly after you pre-educate yourself a bit about the issues and terms.

One problem is net metering agreements can change, so part way into your system life and costs based on current conditions, things can change. In general, I would expect them to change not in your favor.

I'm not sure of the federal tax CREDIT status since the current 30% credit expires in 2016. That would be another thing to understand about limits and time frames.

 

[houstonscott]

Give it few month and then go over it. Rap the panel and listen for a rattle. Or listen to it during windy weather. I would recommend to use a torque wrench because of the stainless steel bolts are easy to strip and it is a pain to replace them. I don't know what the required torque is but I went through the pain of replacing few bolts. How about picture?

I think I put one up, but here you go. HS

 

[houstonscott]

360 kWh is average monthly usage year round for Mom's home... so your array would be enough to power two 2400 square foot 4 bedroom, 2.5 bath homes in her California neighborhood.

I read that the average U.S. Home used 40kwh a day. I am making about 35kwh a day. The house is 3000sq with central AC, I have a pool too, with a pump running 24/7. The AC is two stage stuff so pretty efficient. The pool pump is computerized and the rpm's are programable, so it's very efficient too. HS

 

[ultrarunner]

I'm thinking the big difference is no one here has A/C... window or central... gas heat is standard.

12kWh per day is regular like clockwork... and this includes an electric Dryer, Electric Range, 20 cu. ft. Refrigerator and 22 cu. ft. Freezer all from the 1960's to about 1980...

 

[houstonscott]

I'm thinking the big difference is no one here has A/C... window or central... gas heat is standard. 12kWh per day is regular like clockwork... and this includes an electric Dryer, Electric Range, 20 cu. ft. Refrigerator and 22 cu. ft. Freezer all from the 1960's to about 1980...

Yeah, new appliances use way less electricity. The house is all electric, winter heating is the real big usage for me. AC is cheap compared to heating. I do have a 32cf refrigerator, and a small 5cf freezer that run 24/7. I'm looking at hybrid water heater, or super insulated, when mine goes, that should help too. HS

 

[Carl_NH]

Made 693.987 kwhs in June, system started on the 8th of June, so July should beat that easy. A question, how often should the hardware on the racking system be checked and tightened. HS

HS - we have the same 21LG300 with solar edge optimizers and this is the first six months - Jan and Feb this year we had 9' of snow so abysmal performance. Then in March-June we hit pretty decent numbers 1042KW the highest. It looks like we will make about 7800KWH this year.

 

[arrow]

That all sounds iffy to me. I would shy away from that dealer from what you have said.

Some research on RI's net metering is needed. There are sites like this one:
Rhode Island Net Metering
But I would certainly talk to your utility directly after you pre-educate yourself a bit about the issues and terms.

One problem is net metering agreements can change, so part way into your system life and costs based on current conditions, things can change. In general, I would expect them to change not in your favor.

I'm not sure of the federal tax CREDIT status since the current 30% credit expires in 2016. That would be another thing to understand about limits and time frames.

Thanks Dave. Helpful site. Buy back for overage from NGrid is "discretionary" but at this point I do not have enough info. When I asked the company rep if these were crystalline or amorphous panels, he couldn't tell me. Seems to me that is a basic question anyone in panels should know. From pictures in their brochure, they looked crystalline. Ultra's suggestion of "leasing" the panels and paying the solar company a reduced electrical rate sounds intriguing.

 

[dave1949]

A general discussion solar PV options and of where batteries do and don't make sense.

Solar + Batteries: The Right Thing to Power my Home? - ReVision Energy

 

[ultrarunner]

^^^ thanks for posting the story...

I've made some minor adjustments at the hospital to minimize the demand factor such as staggering start time for the HVAC systems... so not everything starts at 5 am in the morning causing a peak for power usage during a 15 minute interval.

 

[Redneck in training]

Thanks Dave. Helpful site. Buy back for overage from NGrid is "discretionary" but at this point I do not have enough info. When I asked the company rep if these were crystalline or amorphous panels, he couldn't tell me. Seems to me that is a basic question anyone in panels should know. From pictures in their brochure, they looked crystalline. Ultra's suggestion of "leasing" the panels and paying the solar company a reduced electrical rate sounds intriguing.

In principle the life span and reliability of Poly or Mono crystal panels is about the same. The actual quality and reliability depends rather on manufacturer. There three basic groups of manuafacturers:
1.) Big established manufacturers with good quality control and substantial R&D.
2.) Established manufacturers with good quality control and some R&D.
3.) Assemblers of panels from parts sourced from the two above.

Considering reliabilty and warranty the best bang for the buck are usually panels from group 2. Here are manufacturers sorted by size: Panel Statistics and here are manufacturers of inverters: Inverter Statistics

 

[ultrarunner]

Who makes the best panels in terms of quality, output and reliability for residential applications?

 

[Redneck in training]

Who makes the best panels in terms of quality, output and reliability for residential applications?

I would guess top 5 sorted by size. Top manufacturers give you 25 years warranty and positive wattage tolerance of the panels. In other words the specified wattage is the same or better than specification.

 

[houstonscott]

When I investigated panels I liked SolarWorld and LG panels. They seemed to have the highest performance, best glass, and heavy strong frames. I choose the LG in the end, they have some new frames that self clean better, and are two sided, and are 18,6% efficient. The best in the industry right now. I did read the Mitsubishi panels have a good reputation for being rugged and are popular in remote areas like Alaska. HS

 

[houstonscott]

HS - we have the same 21LG300 with solar edge optimizers and this is the first six months - Jan and Feb this year we had 9' of snow so abysmal performance. Then in March-June we hit pretty decent numbers 1042KW the highest. It looks like we will make about 7800KWH this year.

What's the most one day production you've gotten yet this year. I'm hoping to break 40kwh today for the first time. HS

 

[Carl_NH]

45 kWh in May - you will see higher output once the sun angle changes in the spring and fall

Today we have exceeded 40 kWh and in Monday too do a good month so far

 

[houstonscott]

45 kWh in May - you will see higher output once the sun angle changes in the spring and fall Today we have exceeded 40 kWh and in Monday too do a good month so far

Wow, 45, that's really humming along. HS