New 5K system install proposal in NJ

ambyamby Registered Users Posts: 13
Hello All,
I have been watchin this forum for last 8 months and sure learned a lot. Convinced that Solar is a good investment with all the rebates going on, I finally got a quote that I am liking. Need your opinion and advice.

My first question is How is Suntech-175 panels? (It is the Chinese company, listed on NY stock Exchange as STP)
Next is, what kind of details I shall ask for before signing any paper?

Thanks in advance.

The proposal is as follows.
My annual usage based on last 12 months is 6000W
Local utility limits the installation to not generate more than usage :(

28 panel of Suntech STP175S-24 (approx 4900W DC to stay within 6K AC)
SMA SunnyBoy SB-6000 Inverter
Unirac Solar Mount

2 story high roof with little more steeper than usual pitch.

Total turnkey cost is quoted as 26K which includes everything (design, permits and rebate paperwork, material, installation, and final inspection)
No Monitoring included in this and will be separate option (not discussed yet)

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: New 5K system install proposal in NJ

    You can do some quick sanity checks with the PVWatts website... Using Newark, 6kW of panels, rest defaults (you can adjust to your roof specifics):
    "Station Identification"
    "City:","Newark"
    "State:","New_Jersey"
    "Lat (deg N):", 40.70
    "Long (deg W):", 74.17
    "Elev (m): ", 9
    "PV System Specifications"
    "DC Rating:"," 6.0 kW"
    "DC to AC Derate Factor:"," 0.770"
    "AC Rating:"," 4.6 kW"
    "Array Type: Fixed Tilt"
    "Array Tilt:"," 40.7"
    "Array Azimuth:","180.0"

    "Energy Specifications"
    "Cost of Electricity:","11.2 cents/kWh"

    "Results"
    "Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
    1, 3.36, 497, 55.66
    2, 4.05, 536, 60.03
    3, 4.58, 651, 72.91
    4, 4.84, 636, 71.23
    5, 5.30, 701, 78.51
    6, 5.33, 661, 74.03
    7, 5.27, 667, 74.70
    8, 5.25, 660, 73.92
    9, 5.06, 641, 71.79
    10, 4.46, 603, 67.54
    11, 3.15, 431, 48.27
    12, 2.87, 415, 46.48
    "Year", 4.46, 7098, 794.98
    You can do a very simple cost of investment:

    $26,000 / (20 years * 7,098kWH per year) = $0.18 per kWhrs

    Not bad... Make sure you really understand your billing agreement with your utility company--and what may change in the future (California keeps playing around with the rules).

    A good utility plan can make your solar system work out very well.

    A bad utility plan can make your system very expensive to operate.

    Suntech (the good German/American company--there are a lot of "Sun" branded panels out there) are very good panels. The ones I am aware of require a positive grounded GT inverter--not a problem, just need to make sure the inverter ordered/installed is configured for positive ground (usual is negative ground).

    If you are unsure exactly which "Sun" panels you have--make sure they (or any brand of panels) give you a picture/photo copy of the label and check for UL/ETL/TUV... or such NRTL Listed panels before they get installed on the roof. Not saying your vendor is a problem--just seems to sneak in as an issue randomly (and rarely) across the US.

    Watch what the installer is doing--as a few questions of both them and the building inspector if you have any concerns. The installation can be better with a well informed consumer.

    -Bill

    PS: If you get snow/freezing conditions, check into the installation that snow slides and ice dams don't cause you grief... Others here can give you more suggestions regarding cold weather than I (last "snow" where I live was a light dusting 30+ years ago).
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ambyamby Registered Users Posts: 13
    Re: New 5K system install proposal in NJ

    Thanks BB for the quick response.
    Suggest me what things I shall get in writing and clarify further?
    This is supposed to be a turnkey project with following payment arrangement

    Due at Contract Signing 10%
    Due at Delivery of Equipment 60%
    Due at Completion of Install 25%
    Due at Service Turnup 5%
  • mike95490mike95490 Solar Expert Posts: 9,358 ✭✭✭✭✭
    Re: New 5K system install proposal in NJ
    amby wrote: »
    Due at Contract Signing 10%
    Due at Delivery of Equipment 60%
    Due at Completion of Install 25%
    Due at Service Turnup 5%

    I'd try to switch to :
    Due at Completion of Install 15%
    Due at permit final & Service Turnup 15%

    Gives the "pros" a bit more incentive to get the permits closed and GT agreements in place, they have enough profit to walk away from just 5%. This puts their labor costs more on the line, IMHO
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
    gen: http://tinyurl.com/LMR-Lister ,

  • ambyamby Registered Users Posts: 13
    Re: New 5K system install proposal in NJ

    Thanks. Will try so.
    Any opinion on material as well as overall costs as such?
    mike90045 wrote: »
    I'd try to switch to :
    Due at Completion of Install 15%
    Due at permit final & Service Turnup 15%

    Gives the "pros" a bit more incentive to get the permits closed and GT agreements in place, they have enough profit to walk away from just 5%. This puts their labor costs more on the line, IMHO
  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: New 5K system install proposal in NJ

    SMA is a solid brand of inverter...

    Regarding costs... It sounds like $26k is after rebates?:
    • $26,000 / (28*175 watt panels) = $5.31 per watt installed
    • $5.31 per watt / 0.70 rebate = $7.58 per watt (before Federal rebate?)
    If this is the price before rebates--very good. If price after rebates--not cheap, not expensive. Check references, get a second quote if you want to validate your first quote.

    A couple of good threads to look at.

    What not to do: Panel Fire Question
    Even good installations need watching: Illustration of 8 KW (DC) GT Solar PV System Install for Residence in Urban Area

    -Bill "not an installer" B.
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • SpartanScottSpartanScott Solar Expert Posts: 41
    Re: New 5K system install proposal in NJ
    amby wrote: »
    Next is, what kind of details I shall ask for before signing any paper?

    Make sure all equipment and details (scope of work) are on the contract you are signing. Find out the warranty the installer is providing, as well as his proof of insurance. I'd recommend contacting some of the installer's previous clients to get their feedback.

    Your sizing and price looks good. To compare I'm paying $6/watt (pre-rebates) including a monitoring system. One thing I would suggest is thinking about a SunnyBoy 5000W inverter...that is if it will lower your price. Even if your 4900W of panels output 110%, you will rarely hit the 5kW AC max. The smaller inverter will also give you better efficiencies on the cloudy, low irradiance days. With 5376W of panels in my system, I was planning on using the SB5000 inverter until just this week when I switched to the SB6000 inverter. Link below will take you to info on my system, which is exactly the process you're going through:

    5 KW Grid-Tie PV Solar System in Mid-Michigan
  • ambyamby Registered Users Posts: 13
    Re: New 5K system install proposal in NJ

    Hi Scott,
    I have read all 3 pages of your thread with great interest and honestly that only prompted me to post my new thread!
    I am also in house for 10 months (11 now)
    4600Sq Ft house with pool and 2 kids.
    I am Extremely tight with any energy usage which is now hurting me as I am limited in what size system I can install.
    I see my electricity usage doubling in next few years (girl growing up wil use hair-dryer, AC will run a lot longer, TVs will be left ON etc).

    I have a near perfect South facing roof and zero shading so am expecting 120% output at peak times.
    Installer did calculation to say 5K worth of panels (28*175) will generate 6000KWH annually.

    Why do you say SB5000 will give better efficiency than SB6000?
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: New 5K system install proposal in NJ
    amby wrote: »
    Why do you say SB5000 will give better efficiency than SB6000?
    Inverters do not have the same efficiency at all power outputs.

    Typically efficiency is highest near peak output. At lower outputs, especially the lower 1/3rd, efficiency drops a good deal.

    I'm sure there are charts that show this behavior somewhere...
  • SpartanScottSpartanScott Solar Expert Posts: 41
    Re: New 5K system install proposal in NJ
    amby wrote: »
    Why do you say SB5000 will give better efficiency on a cloudy day than SB6000?

    The SunnyBoy inverter datasheet (under Service/Downloads on SMA website) shows that the inverter efficiency drops fast below 20% of its rated power. (see attached chart) When your panels are kicking out 1000W, the SB6000 inverter would have a ~92% efficiency, where the smaller SB5000 inverter would still be up at ~95% efficiency because it hasn't hit this drop off yet. This is more of an issue for me with lake effect clouds all winter, and the inverter running at 10-20% capacity.

    With your perfect south facing roof, and steep angle to catch more winter sun, I agree that you should stick with the SB6000. Just wanted to mention the option in case you could save $ by reducing to SB5000.

    If you are even thinking of monitoring I would include that in this install. My tax advisor said that adding the monitoring system in the future would not qualify for the 30% Fed Credit, where if you wrap it in the PV install now it will be covered. Could you confirm that your price is pre-rebates? What rebates will you receive from state/utility other then the 30% federal?

    Thanks,
    Scott
  • BB.BB. Super Moderators, Administrators Posts: 32,006 admin
    Re: New 5K system install proposal in NJ

    Larger inverters may have larger or more FETs to support the higher power conversion--at lower power conversion, these larger components have more paracitic losses (such as capacitance), so can be less efficient at lower input power levels (fixed larger losses vs lower power conversion).

    Some of the newer inverters (if I understand their glossies correctly) will have, for example, 3 conversion sections, and turn off one or two of those converters at lower input energy levels--keeping their efficiencies higher over the entire range.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ambyamby Registered Users Posts: 13
    Re: New 5K system install proposal in NJ

    Thanks all for the responses to my thread. I have been learning a LOT on this forum. Spent last 2 days reading through the 20+ pages of Plano TX installation. Very informative and interesting set of postings.

    Well, the proposal I got is very competetive and the company is also not a small time operator. they have done a decent number of installations in the NJ/NY area.
    The Sales guy who I am speaking too has made one trip to our house and that too was for a coversation and explain their offering. He says that a few good pictures alongwith some ground based measurements will give good enough idea to the engineers who will then prepare a preliminary design. When I express my concerns regarding shading from chimney and dormers, and also the vent fan and other vent pipes in middle of good clean roof area, he says it is no economical for them to send enginees up on the roof for every quotation, and all of that will happen after the contract is signed.
    No money is due till the material is delivered but I am still not getting the level of comfort needed for mocing forward.

    PLEASE ADVICE how to tackle the situation.....
    The more I read here, the more I understand how a good installation and a bad installation can be different and what small small things, if not kept in mind, will go wrong. Challenge is the guy is convinced all will be good and "they know it all because of their experience".
    :confused:
  • dreesdrees Solar Expert Posts: 481 ✭✭✭
    Re: New 5K system install proposal in NJ

    amby - you should ask to see some reference installations where you can get up and personal with their work. Try to get some that are similar in scope to your install.
  • SpartanScottSpartanScott Solar Expert Posts: 41
    Re: New 5K system install proposal in NJ

    Your salesman was not to smooth with his choice of words. He made it sound like you should pay, and then you may get stuck with what they do. He should have made it clear that once you sign, his men will go up and measure the roof to place the panels in a location where they will not get shaded. If they find a vent pipe in the way, they will move it. Give him a call and confirm if that's the case. I would not sign with them until you are convinced (or have it in writing) that it will have zero, or minimized shading. On my roof I was concerned about a stink pipe in a prime panel location. I made sure to put in the contract the relocation of this pipe.

    -Scott
  • Ralph DayRalph Day Solar Expert Posts: 952 ✭✭✭✭
    Re: New 5K system install proposal in NJ

    Amby
    Don't expect prolific waste from growing children. They are exposed to lots of information about conservation and such...should actually be teaching you. If they develop habits, yes habits of shutting down computers, tvs, room lights when leaving...then the habits developed will save everyone from lots of yelling about shutting things off.

    A status monitor that shows voltage, amps being used etc is a great tool in that learning curve. Watch what the draw on the system is then shut down unused lights...you/they/princess will see the reduced load and hence longer tv watching time is available (or some such reward).

    Conservation habits save on your installed base price and on the amount of energy you use.

    Ralph
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