Critique my hypothetical system?

Mike 870Mike 870 Registered Users Posts: 42 ✭✭✭

Hi, I've selected some components from the host site that I plan to buy this spring or summer.  I would greatly appreciate any feedback you experts might suggest regarding system design, balance of system, component selection, breaker sizes, wire sizes, anything goes.  I've listed everything in order from the Panels down to the battery bank and given some rationale as to why I selected those components.

Sizing:  Sized by analogy to my RV battery and then "designed to cost".  I can boondock for 2 days with no solar off my 80 AH RV battery, if I conserve a lot.  Knowing what I can get by on, and knowing I can buy a larger system,  I "designed to cost" of around $2,000 dollars.  (I think solar companies would get more sales if they designed to cost, then explained the limitations of the system)  This is for a 300 Sq ft. weekend cabin on the OH, KY border.  Cistern, RV LED lighting, propane fridge etc. 

Panels: 2 Kyocera Ku-270 for nominal array size of 540 watts. Vmp 31, Imp 8.71, Voc 38.3 Isc 9.43   roof mount 45 degrees (12/12 roof pitch).  Open to suggestions, picked this because I have a 150 watt Kyocera and it seemed to be of high quality.  Good balance between name brand and $/watt.  Freight shipping is a bummer.

Panel to controller wiring TBD: I don't know if I should wire series or parallel.  Is there such thing as too much head for a charge controller (FM60)?  I have not been able to find out the implications.  Wire length could be about 35 feet.  If Parallel I will buy a combiner box and run 8 gauge cable, if series I'll just by the H4 10 gauge solar cable. 15 amp or 25 amp breaker depending on configuration.

Charger FM 60: I'm in that awkward size of too big for a 30 amp controller.  I like the data logging and features the FM 60 brings.

Charger -> Battery 4guage 60 amp breaker 5ft at most

Battery Bank: 2 Crown CR-275. 275 AH @ 12v.  My wife is from the town where the crown factory is, and I'm there often.  I can get the batteries for wholesale without shipping.

Inverter: SA300 w 50A breaker 6 ga wire, short wire length TBD. Almost all loads are 12vdc so the inverter will see battery charging duty and small loads not worth starting the generator for.

Battery Charger: Iota DLS45, 6 ga wire 45 amp breaker

Miscellaneous: Midnight Surge Protector.  Does this go inline between the panels and charge controller?  Analog meters, I think they are cool so I will add some mostly for fun.  Roof mount racks,  I don't know what I need I will ask NAWS on the phone. Stud rings, baby boxes, battery interconnect cable for series connection (not sure how to size this).  I already own a Honda EU6500 IS tri fuel genny.

Thanks for reading,

Mike

Comments

  • PhotowhitPhotowhit Solar Expert Posts: 5,729 ✭✭✭✭✭
    System voltage?

    Do you have a charge controller that you can use with you existing panel? or is that not part of this system?

    Thoughts, Shipping is a bummer! While I love NAWS and have high respect for Kyocera, but might be able to have more for less, going with other brands and smaller wattage that would ship cheaper and if you were not planning to expand your system (?) would work with a cheaper PWM charge controller.

    Perhaps 4 of these 165 watt panels for $660 shipped;
    https://www.amazon.com/Solar-Panel-Charging-Battery-Efficiency/dp/B00G2IZ1VW/ref=sr_1_1?ie=UTF8&qid=1482436993&sr=8-1&keywords=165+watt+solar+panels

    and a Morningstar 45 amp charge controller for $155 (or the 60 amp for $40 more)
    https://www.solar-electric.com/trts12vochco.html

    While the shipped price of the panels will likely be the same, the savings in the charge controller could afford you to buy 2 more panels...

    If it's a 12 volt system you would need to add a combiner box. I would guess it is since mostly DC loads, another $150 or so... or inline fuses;
    https://www.amazon.com/E-accexpert-Connector-Holder-Waterproof-Replaced/dp/B018I953ZG/ref=sr_1_9?ie=UTF8&qid=1482437916&sr=8-9&keywords=mc4+fuses

    If you only have 2 panels or strings you do not need a combiner box, they can be safely run in parallel with no issue!

    Living on DC does present some issues, such as a DC pump in your cistern, how far will it be away from your battery bank, how heavy a wire will you need to run...

    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Mike 870Mike 870 Registered Users Posts: 42 ✭✭✭
    Hey thanks for the response photowit,

    Yes the system was based on a 12v bank, the crowns are 6v  batteries in series.  Funny you should ask if I have a controller with my panel, in fact, I do and when I bought it with the Kyocera 150 watt panel I upgraded it to the Morningstar Prostar 30 with digital display just so I could be above $500 and get free shipping.  I use that for my RV.  I guess I could use that controller, change this new system to 24 volt battery and put the saved money towards panels batteries and 24-12v step down converter.  I only need a 10 amp controller for my RV system. 

    I have considered a PWM controller as well.  I recently read a bogart engineering white paper on why they chose to make their controller PWM vs. MPPT.  Truth is I don't have a lot of experience or knowledge to make the decision. 

    I had considered some of the lower cost per watt small panels around but was hesitant to pull the trigger on them.  I haven't seen a single reputable retailer selling 32 cell panels for the $1/watt price range that you can see on amazon or ebay.  I figured there has to be a reason why.   I'm not totally against the idea, just suspicious. 

    My cistern is buried under my foundation, it would probably be about a 10 ft. run from the pump to the load center.  Its a shurflo revolution that draws 7 amps at 12v running at max rate. 
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I would check around locally for panels. I have Kyrocera and they work fine but I got 22 of them at once so the per unit shipping was bearable.

    Battery interconnects - make them as big and as short as you can (like 4/0 x 12"). No such thing as too big.

    Panels could be either series or parallel. Charge controller might be a bit more efficient going from around 30v in parallel vs 60v in series. I have my 12v wired 2s2p and the CC handles it fine though. If there is any roof space for expansion I'd probably run good sized parallel to make it easier to add later. I would do a combiner box with breakers just to make it easier to isolate panels and/ or expand, but that's just me. If cost of wire is really important serial should work fine too though.

    If there was any way to avoid putting the panels on the roof I'd think about it. A 45 degree roof is pretty steep to work on.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • PhotowhitPhotowhit Solar Expert Posts: 5,729 ✭✭✭✭✭
    Mike 870 said:
    I had considered some of the lower cost per watt small panels around but was hesitant to pull the trigger on them.  I haven't seen a single reputable retailer selling 32 cell panels for the $1/watt price range that you can see on amazon or ebay.  I figured there has to be a reason why.   I'm not totally against the idea, just suspicious. 
    Did you follow my link? Did you notice the price was for 2 panels 330 watts for $300, Good reviews at Amazon and <$1 a watt before shipping. I think you mean 36 cell panels as 32 would be too low a vmp, (history though, they use to make some 32 or maybe 34 cell panels that they claimed you could use without a charge controller!)
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • Mike 870Mike 870 Registered Users Posts: 42 ✭✭✭
    Ohh yea I did mean 36 cell.  Yes I did follow the link.  I guess this leads me to another design question.  I had roughly been trying to match my array size to 10% of my battery capacity.  If the bank has 5 days to charge and weekend use, should I go for more battery and less panel on that spectrum, maybe 7 or 8 %?


    Estragon, I have a lot of options on mounting, I could put them on the ground or on the porch roof which is less pitch.  I have a nice field in front of the cabin without any tall trees in the way.  This field is bigger than it looks and the cedars are not very tall.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    A good system design is always to determine loads, , then match the battery bank to serve that demand  + autonomy, then design the array to fully recharge your batteries and at the same time power some of the daytime loads...don't under-panel as there are sytem losses , wiring, connections, CC, Inverter, etc...  And , just remembered make sure the winter conditions do not produce too much Voltage for the CC, use the CC manufacturers String sizer...
    have fun over the holidays...
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    Hard to tell from the pic but you're likely okay shade-wise. It looks to me like the cedars wouldn't be your problem - it would be the deciduous trees behind. Even bare branches will shade enough to kill output.

    At your latitude the sun should be high enough to clear them though. Right about now will be about as bad as it gets so if you happen to be out there it wouldn't hurt to check any potential locations.

    Looks like a nice spot!
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
    Agree, those Aspen/Poplar (?) are a big problem  asi is if the panels get any of those branches  casting a shadow...  I was blown away at the losses before I yelled Timber!   AND they grow verrrry fast since they are almost a weed..
    The shadow was almost invisible in the late fall!
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • Mike 870Mike 870 Registered Users Posts: 42 ✭✭✭
    I know it's hard to believe from looking at the picture, but it's nothing but blue sky.  There is a bit of perspective/distortion going on.  Thank you for the input everyone.
Sign In or Register to comment.