Grid-tied solar

/ Grid-tied solar #281  
I have been outside in minus 20 degree weather and felt the compressor line coming into the house and it is too hot to grab on to. The heat pump does lose considerable efficiency when temps drop below 20 or 30 but it pumps heat all winter long. In the event it runs 45 minutes (adjustable) without bringing the house to temp, resistant heaters kick on and spin my electric meter.

My light bill alone is around $100/month but I have 2 offices at home that are occupied.
 
/ Grid-tied solar #282  
I have been outside in minus 20 degree weather and felt the compressor line coming into the house and it is too hot to grab on to. The heat pump does lose considerable efficiency when temps drop below 20 or 30 but it pumps heat all winter long. In the event it runs 45 minutes (adjustable) without bringing the house to temp, resistant heaters kick on and spin my electric meter.

My light bill alone is around $100/month but I have 2 offices at home that are occupied.

That's remarkable, and I would remark, but I don't know what to say. I have a really thick and comprehensive refrigeration book a friend gave me recently, and I will be looking into this a bit later in the week to see what it says about various scenarios, since clearly my expectations are a bit off.
 
/ Grid-tied solar
  • Thread Starter
#283  
Time for the October results.

We are still slightly above the model even though this wasn't a great month. Haven't seen the sun since Saturday when storm Sandy started moving in. The rest of the month was up and down, several bad days, several good days.

My net usage was 391.6 KWH of which the system produced 378.6 KWH, so I used up 13 KWH credits and still have 129 KWH credits from prior months.

The PVWatts model AC kWh predicted/actual:
Aug. 383/460.7
Sep. 394/480.9
Oct. 369/378.6
Nov. 283/TBD
Dec. 331/TBD
 
/ Grid-tied solar #284  
My October. At bottom of "picture" you can see the two year trend.

October 2012.JPG
 
/ Grid-tied solar
  • Thread Starter
#285  
The November results.

This month was a lot better than the model, or what I expected. We did have a 5-6 day stretch of clear sunny weather that really piled on the kilowatts. On clear days, the panels are producing their full rated power for a couple hours mid-day now, with the lower sun angle and lower temperatures (highs below 45*).

My net usage was 442.3 KWH of which the system produced 400.3 KWH, so I used up 42 KWH credits and still have 42 KWH credits from prior months. Net usage was 50 kWh above last month due to Thanksgiving cooking, more hot water use in the kitchen and showers (had company), and longer night hours causing more lighting use.


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/TBD
Jan. 388/TBD
Feb. 412/TBD
Mar. 509/TBD
Apr. 374/TBD
May 353/TBD
Jun. 308/TBD
Jul. 341/TBD
 
/ Grid-tied solar
  • Thread Starter
#286  
The November results.

This month was a lot better than the model, or what I expected. We did have a 5-6 day stretch of clear sunny weather that really piled on the kilowatts. On clear days, the panels are producing their full rated power for a couple hours mid-day now, with the lower sun angle and lower temperatures (highs below 45*).

My net usage was 442.3 KWH of which the system produced 400.3 KWH, so I used up 42 KWH credits and still have 42 KWH credits from prior months. Net usage was 50 kWh above last month due to Thanksgiving cooking, more hot water use in the kitchen and showers (had company), and longer night hours causing more lighting use.


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/TBD
Jan. 388/TBD
Feb. 412/TBD
Mar. 509/TBD
Apr. 374/TBD
May 353/TBD
Jun. 308/TBD
Jul. 341/TBD
 
/ Grid-tied solar #287  
I have a small, 1070 sf, all electric home in South Dakota. I use between 1200 kw and 4800 kw per month with an electric heat pump for heat. I use roughly 3 times more electricity in just my lighting when there is no heat or cooling needs then what you use in a month year round. You either sit in the dark or your reported usage is BS to make your photovoltaic system look better. I am extremely skeptical of your reported electrical usage.
 
/ Grid-tied solar #288  
Sorry sdkubota, but you are the one way off base here. Just checked my electric bills online. My wife and I use about 200-400 kwh per month. Perfectly normal. Your own electrical usage is astronomical and frankly, completely ridiculous. I think you have a serious issue with one of your appliances, or an insanely inefficient heat pump. Please do a little more research before you call BS on Dave.

Dave, many thanks for continuing to report your solar performance. This thread will hopefully become a good resource for me as I get closer to purchasing my own system.
 
/ Grid-tied solar
  • Thread Starter
#289  
I have a small, 1070 sf, all electric home in South Dakota. I use between 1200 kw and 4800 kw per month with an electric heat pump for heat. I use roughly 3 times more electricity in just my lighting when there is no heat or cooling needs then what you use in a month year round. You either sit in the dark or your reported usage is BS to make your photovoltaic system look better. I am extremely skeptical of your reported electrical usage.

Geez. No BS here, I'm too old to start lying to strangers or anyone else. But I do remember suggesting to you that you investigate your extremely high usage. Several others too, tried to tell you it doesn't seem right. The average electricity usage by Maine households is ~600 kWh per month.

My usage has now been measured with three different utility meters, our old analog, the smart meter that replace that, and now the in and out meters that replaced the smart meter. They all agree with each other, so it is what it is. If my inverter was over-reporting it's output, that would show up in my electric meters as unaccounted for consumption.

Just my wife and I live here. We don't have air conditioning, our heat comes from sunshine and a masonry wood stove, no blowers, pumps or burners to power. Our lights are almost all compact fluorescents, they were purposely located to be most effective, ie, we are only lighting the area we use, not making the whole room bright. We have a dual-fuel range, propane burners and electric oven. Electric dryer and, now an elec. water heater which added about 100 kWh per month to our usage. We are on a well with an electric pump. I use a power tool now and then, but I don't often run things like my welder or a large air compressor.

Other than those things, what should I use power for?

Today is good solar day, I have an hour of decent daylight left and have already generated 22 kWhs. What can I tell you?
 
/ Grid-tied solar #290  
dave1949 said:
Geez. No BS here, I'm too old to start lying to strangers or anyone else. But I do remember suggesting to you that you investigate your extremely high usage. Several others too, tried to tell you it doesn't seem right. The average electricity usage by Maine households is ~600 kWh per month.

My usage has now been measured with three different utility meters, our old analog, the smart meter that replace that, and now the in and out meters that replaced the smart meter. They all agree with each other, so it is what it is. If my inverter was over-reporting it's output, that would show up in my electric meters as unaccounted for consumption.

Just my wife and I live here. We don't have air conditioning, our heat comes from sunshine and a masonry wood stove, no blowers, pumps or burners to power. Our lights are almost all compact fluorescents, they were purposely located to be most effective, ie, we are only lighting the area we use, not making the whole room bright. We have a dual-fuel range, propane burners and electric oven. Electric dryer and, now an elec. water heater which added about 100 kWh per month to our usage. We are on a well with an electric pump. I use a power tool now and then, but I don't often run things like my welder or a large air compressor.

Other than those things, what should I use power for?

Today is good solar day, I have an hour of decent daylight left and have already generated 22 kWhs. What can I tell you?

Whether or not I ever go solar, you are a true inspiration. During the sunny winter days, our heat is supplied by the sun shining through Windows. 70+ degrees inside right now :). Evening til morning is the wood stove.

Keep up the great work. Enjoy learning from you and others throughout the forum.
 
/ Grid-tied solar #291  
Burning wood is extremely harmful to the atmosphere and release numerous carcinogen contaminates..
 
/ Grid-tied solar
  • Thread Starter
#292  
Burning wood is extremely harmful to the atmosphere and release numerous carcinogen contaminates..

Yes it does. I burn less than a cord of wood per year. Aside from the tractor and chainsaw fuel used to harvest it, it has the virtue of being carbon-neutral.

You, on the other hand, need your own coal mine. Don't get mad at me, look into your usage.
 
/ Grid-tied solar #293  
Geez. No BS here, I'm too old to start lying to strangers or anyone else. But I do remember suggesting to you that you investigate your extremely high usage. Several others too, tried to tell you it doesn't seem right. The average electricity usage by Maine households is ~600 kWh per month.

My usage has now been measured with three different utility meters, our old analog, the smart meter that replace that, and now the in and out meters that replaced the smart meter. They all agree with each other, so it is what it is. If my inverter was over-reporting it's output, that would show up in my electric meters as unaccounted for consumption.

Just my wife and I live here. We don't have air conditioning, our heat comes from sunshine and a masonry wood stove, no blowers, pumps or burners to power. Our lights are almost all compact fluorescents, they were purposely located to be most effective, ie, we are only lighting the area we use, not making the whole room bright. We have a dual-fuel range, propane burners and electric oven. Electric dryer and, now an elec. water heater which added about 100 kWh per month to our usage. We are on a well with an electric pump. I use a power tool now and then, but I don't often run things like my welder or a large air compressor.

Other than those things, what should I use power for?

Today is good solar day, I have an hour of decent daylight left and have already generated 22 kWhs. What can I tell you?

So your water heater runs 15 hrs/month then or 1/2 hr per day. Do you bath with a wash cloth and wash your clothes in the river?
 
/ Grid-tied solar #294  
dave1949 said:
Yes it does. I burn less than a cord of wood per year. Aside from the tractor and chainsaw fuel used to harvest it, it has the virtue of being carbon-neutral.

I have a fairly new stove. My understanding is that it burns much of what used to go up the chimney. Some stoves even have catalytic converters. Are you sure the new wood stoves are bad pollutants? I thought it was different now.
 
/ Grid-tied solar #295  
I have a fairly new stove. My understanding is that it burns much of what used to go up the chimney. Some stoves even have catalytic converters. Are you sure the new wood stoves are bad pollutants? I thought it was different now.

You're killing Mother nature...
 
/ Grid-tied solar #296  
So your water heater runs 15 hrs/month then or 1/2 hr per day. Do you bath with a wash cloth and wash your clothes in the river?

Let's determine his element size based on your assumption:

If he says it is 100kWh per month, and you say that is 15 hr per month, then 100kWh/15h (cancels the hour unit out)= 6.66 kw element (6666 watt element.) Most heaters I have ever seen have something closer to a 1500W element(s) or less, and they run one at a time. Based on that, then

100kWh / 1.5kW (cancels the kW unit out)= 66.67 hours of element run time, or a little over 2 hours a day in a month.

I'm not really trying to be a smarty pants. I am trying to show you some of the stuff you may need to use to figure out why your electricity usage is quite high. I hope I have not made any errors...I'm tired and my eyes are dry.
 
/ Grid-tied solar #297  
sdkubota said:
You're killing Mother nature...

Mother nature isn't real. So, I can't kill her.
 
/ Grid-tied solar
  • Thread Starter
#299  
So your water heater runs 15 hrs/month then or 1/2 hr per day. Do you bath with a wash cloth and wash your clothes in the river?

Actually, the 50 gal. water heater, which is very well insulated by a foam jacket encased in some sort of vinyl skin, has a max power usage of 3800 watts, which means it could run at it's max rating for 52.6 minutes per day, assuming 100 kWh per 30 day month. I don't believe it runs at its max wattage rating. It might come close for a short time when it first turns on an element at the start of a heating cycle, but I don't have the meters to find out.

100 kWh / 30 days = 3.33 kWh/day average usage.
3.33 kWh / 3.8 kWh = 0.876 hours X 60 min/hr = 52.56 minutes

If the element operates at 75% of its max rated power (.75 X 3.8 = 2.85) most of the time:
3.33 kWh / 2.85 kWh = 1.168 hours X 60 min/hr = 70.1 minutes

Somewhere between 52 and 70 minutes of operation time per day is enough for a couple of showers and hand washing. Our dishwasher heats has its own water heater and has only a cold supply line.
 
/ Grid-tied solar #300  
Thanks for the report. I just finished and put on line 7.5 kW array yesterday afternoon and need to finish wiring of second 8.25 kW array tomorrow and put it on line. So far I don't have production data due to issues with the Envoy monitoring system apparently due to distance from the arrays.
 

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