Maximum output of a Grid TIe system

solar_davesolar_dave Solar Expert Posts: 2,344 ✭✭✭✭
Sort of to parallel the off gridders let's here about how everyone's spring is looking. My system is approaching optimum angle in 8 weeks or so, but the length of day is continuing to increase, but so is the panel temps.

My Max day so far this year was Wednesday and Thursday this week with 73Khw produced, with Wednesday producing a 37Kwh reverse on the meter. Wheeeee! ;) I suspect the next 4-8 weeks will produce a sizable excess for my summer cooling bank. As of March 3 we had 1048 Kwh in the on-peak credit column and a still $125 credit carry over from last years production. A bit nervous of an early heat wave however, they are predicting 90+F for next weekend.

The one Red bump in load is the pool pump running, a new programmable controller is in the works to run it full force for 1 hr to floor clean/skim and then a 2-3 hour period low volume to filter and stir only (about 800 watts). Below is a 24 hour snap shot from this morning with full sun days predicted for the next week.

Yellow = voltage
Red = main house load
Pink = new building load
Blue = net production
Green = solar production (the good stuff)

System specs in my signature. :cool:

Comments

  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Maximum output of a Grid TIe system

    Best day I've had so far on my new system is 35.311 kWh last Wed. Mar 23.
    This is my new 5520W system with due south orientation and 20deg tilt.
  • JburgessJburgess Solar Expert Posts: 130 ✭✭✭
    Re: Maximum output of a Grid TIe system

    I’ve been doing 59-60Kwh days Wed. to Fri. with my 9.7KW system.

    Picking up 16 more KD210 panels next week to bump it up to 13KW. Looking forward to meeting over 90% my needs by solar this summer.
  • Ralph DayRalph Day Solar Expert Posts: 887 ✭✭✭✭
    Re: Maximum output of a Grid TIe system

    Wow!

    I'd be excited about 35,000 plus kwhrs in a day from a 5+kw system!!

    Maybe meant 35,000watt hours?:confused:

    I have been harvesting 80-85kwhrs out of my 10kw system over the last few days.

    Ralph
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Maximum output of a Grid TIe system

    My best day so far this year was Wednesday when I hit 28.2 kWh.

    From October to 12 March I pushed 894 kWh excess to the grid.

    We've been looking at our finances and it looks like sometime around the end of May, beginning of June I'll be able to buy the new battery pack for my truck and can start using up some of that excess energy.

    My power company only pays $0.04 per kWh excess when we settle up in September, so the way I figure it, it will only cost me 4 cents per kWh to charge my truck or a bit over 1 cent per mile.
  • cpetkucpetku Registered Users Posts: 22
    Re: Maximum output of a Grid TIe system

    I hit 50KWh today on an 8.6KW array in Michigan (lat 42.7... degrees). However I have some minor shading in the morning until 11:00 that needs to be considered.
  • solar_davesolar_dave Solar Expert Posts: 2,344 ✭✭✭✭
    Re: Maximum output of a Grid TIe system

    The heat has hit here! Now running the AC about 7-8 hours a day, hit 100F yesterday :cry: second earliest on record. Output down to about 9000 watts at noon. Back of panel temps over 130F. We still produced an excess to the grid of 13 Kwh and $3.25 on Friday. Me thinks the excess will be short lived this year and wish the Kwh bank had more in it.

    Edit: Mar was a great production month, PVwatts says we should produce 1729 kWh and we actually produced 1969 kWh according to the TED, so I should not whine so much. ;)

    Me likes the bill as well:

    Cost of net electricity
    Basic service charge $6.90
    Delivery service charge $0.00
    Environmental benefits surcharge $0.00
    Federal environmental improvement surcharge $0.00
    System benefits charge $0.00
    Power supply adjustment* $0.00
    Metering* $5.39
    Meter reading* $1.80
    Billing* $2.03
    Generation of electricity on-peak* $0.00
    Generation of electricity off-peak* $2.90
    Transmission and ancillary services* $0.00
    Transmission cost adjustment* $0.00
    Cost of electricity you used $19.02

    Taxes and fees
    Regulatory assessment $0.06
    State sales tax $1.28
    County sales tax $0.14
    City sales tax $0.43
    Franchise fee $0.38
    Cost of electricity with taxes and fees $21.31
    Total charges for electricity services $21.31


    My credit with the utility is shrinking now down to about ($88 )
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: Maximum output of a Grid TIe system

    I'm almost at "sun straight into the array" time here, but with all the cloudy weather we've had of late, I'm not making squat. Peak for me was 16.7 KWh (2.8KW array) in early March. I should be much higher, but again -- horrible weather.
  • autoxsteveautoxsteve Solar Expert Posts: 114 ✭✭✭✭
    Re: Maximum output of a Grid TIe system

    The highest day I have had in just over 3 years was 29 kWhr in early March of 2009. It was a cold day and windy but sun all day long.

    As an example, I produced 26 kWhr today as the system ran for 12 hours, 26 minutes.
    peak output power was 3.48 kW today
    (4.18kW sys)
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Maximum output of a Grid TIe system

    I did 84kWhr yesterday, this is with a 14kw system. If I would get on the roof and clean the panels I could do a bit more

    I have two Xantrex GT5.0's a GT3.3 and a XW6048 to sell the energy
  • solar_davesolar_dave Solar Expert Posts: 2,344 ✭✭✭✭
    Re: Maximum output of a Grid TIe system
    I did 84kWhr yesterday, this is with a 14kw system. If I would get on the roof and clean the panels I could do a bit more

    I have two Xantrex GT5.0's a GT3.3 and a XW6048 to sell the energy

    I hear about panel cleaning, mine need it too! Was a bit cooler here yesterday and did 74kWh of my 12.5 kw system. Nice and clear and cool this AM but the weather man is predicting some clouds blowing in.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Maximum output of a Grid TIe system

    Woohoo! We hit 29.3 kwh yesterday a new record for my system.

    I need to get out there and clean my panels too, I can see the layer of dust on them and with the weather warming up their output is dropping enough that the inverters aren't maxed out in the late afternoon.
    I can probably get an extra couple hundred wh with clean panels.
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: Maximum output of a Grid TIe system
    solar_dave wrote: »
    I hear about panel cleaning, mine need it too! Was a bit cooler here yesterday and did 74kWh of my 12.5 kw system. Nice and clear and cool this AM but the weather man is predicting some clouds blowing in.

    You can spot the difference between "dirty" and "hot" by looking at the voltage as compared to the current.

    "Dirt" lowers current, "Hot" lowers voltage.

    And yeah, mine are filthy. I normally get between 99 and 100 percent of the temperature corrected output. Lately I've been stuck below 96 percent :(
  • solar_davesolar_dave Solar Expert Posts: 2,344 ✭✭✭✭
    Re: Maximum output of a Grid TIe system
    tallgirl wrote: »
    You can spot the difference between "dirty" and "hot" by looking at the voltage as compared to the current.

    "Dirt" lowers current, "Hot" lowers voltage.

    And yeah, mine are filthy. I normally get between 99 and 100 percent of the temperature corrected output. Lately I've been stuck below 96 percent :(

    Understand,
    I just check the back to the panel with an infrared gun = HOT (saw temps of 135F on the back of the panels), Also outdoor temps of 100F make it pretty clear I am temp impacted.

    Visual to determine Dirt level = Obvious
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Maximum output of a Grid TIe system
    I did 84kWhr yesterday, this is with a 14kw system. If I would get on the roof and clean the panels I could do a bit more

    I have two Xantrex GT5.0's a GT3.3 and a XW6048 to sell the energy

    OK, I'm within running distance to Solar Guppy, it wasn't burning hot on 4/4, and in the morning it was pretty nice. However, with a 4.7kw system (essentially 1/3 of Solar Guppy's) I had 12.70kwh and 10.07kwh for each string, total 22.77. So my system, with an XW6048 also but with two xw mppt60-150s, did 80% of what would be expected if both were equal. And, what is also strange, the larger string has 33% more panels in the same orientation as the smaller string, but consistently puts out only about 25% more.
  • tallgirltallgirl Solar Expert Posts: 413 ✭✭
    Re: Maximum output of a Grid TIe system
    OK, I'm within running distance to Solar Guppy, it wasn't burning hot on 4/4, and in the morning it was pretty nice. However, with a 4.7kw system (essentially 1/3 of Solar Guppy's) I had 12.70kwh and 10.07kwh for each string, total 22.77. So my system, with an XW6048 also but with two xw mppt60-150s, did 80% of what would be expected if both were equal. And, what is also strange, the larger string has 33% more panels in the same orientation as the smaller string, but consistently puts out only about 25% more.

    What's the temperature profile of the larger string? Does it get more sun later in the day?

    This is one of those things where if you have to pick south-east or south-west, pick south-east -- the air temperature is lower, and the array will produce better.
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Maximum output of a Grid TIe system
    tallgirl wrote: »
    What's the temperature profile of the larger string? Does it get more sun later in the day?

    Both strings are on the same roof, one string (9 panels) is on the lower portion of the roof, and one string is on the same roof but higher up (11 panels) with the 12th panel extending the lower row to 10 panels.
  • Peter_VPeter_V Solar Expert Posts: 226 ✭✭✭
    Re: Maximum output of a Grid TIe system
    Both strings are on the same roof, one string (9 panels) is on the lower portion of the roof, and one string is on the same roof but higher up (11 panels) with the 12th panel extending the lower row to 10 panels.

    I'm guessing you're not using active attic ventilation (fans)? The higher up the slope of the roof, the higher the internal temperatures and I'm pretty sure the roof surface will also have higher external temps which would make the higher array hotter.
  • Solar GuppySolar Guppy Solar Expert Posts: 1,962 ✭✭✭
    Re: Maximum output of a Grid TIe system

    I have few advantages Sub,

    I have about 6kw that faces south east, so the harvest is during a much cooler part of the day

    Only 4kw of my arrays feeds the XW-6048, the rest is all in the high efficiency GT's. While The XW isn't too bad maybe 2% lower than the GT's, you have an additional 2-4% loss in the charge controllers and whatever the battery's are snorting while the battery's are held in a sell voltage

    Finally, I have my panels 6+ inches from the roof and 2" spacing between panel to panel so it has good ventilation
  • sub3marathonmansub3marathonman Solar Expert Posts: 300 ✭✭✭
    Re: Maximum output of a Grid TIe system

    I knew Solar Guppy had everything figured out to maximize the output. I don't think any sunlight hits his roof except possibly on the north side.

    But, along with Peter_V's comment, it just didn't seem hot enough that such a dramatic decline in output would be occurring. I could understand in July or August, but not here in April.

    I too wondered if the top row was hotter than the bottom row, but figured the difference couldn't be much, if anything. I really hadn't thought about the heat radiating from the attic underneath, but that does seem very likely too.
  • solarixsolarix Solar Expert Posts: 713 ✭✭
    Re: Maximum output of a Grid TIe system

    Update after the snow we just had.
    New record of 37.818 kWh Sunday, Apr 10. Clear, clean, and cold!
    Its been running about 35kwh on typical clear days.
    This is my new 5520W system with due south orientation and 20deg tilt.
    Comes to 6.85 hours of effective sun.
    NREL rating for our area is about 6.35hr I figure.
  • pogonippogonip Registered Users Posts: 14
    Re: Maximum output of a Grid TIe system

    I had the best day every a few days ago. 18Kw on a 1575 watt system. The temp was between 0 - 30 degrees. The ground is still covered with snow. The sun was up for 14+ hours and the tracker followed if through 210 degrees. But in December I may only get 100 watts in a day and that is when the sun is shining.

    Dan
  • CJW8CJW8 Registered Users Posts: 23
    Re: Maximum output of a Grid TIe system

    I have been getting 52-53 kWh for the last 3 days on my 7 kW inverter with 8 kW of panels. Average per day since June 1st is 30 kW. Prescott AZ
  • RavsRavs Registered Users Posts: 13
    Re: Maximum output of a Grid TIe system

    My 5.67 kw system is approaching theoretical max output by mid May, but cool clear days recently have resulted in 41 kWH back to back days. I cant image it could get any higher, even with longer days ahead. Coming up on first summer with the system.
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