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Thread: Solar Boost 2000E input voltage

  1. #1

    Default Solar Boost 2000E input voltage

    Hi friends,

    I've just joined the club. I received my 2 Kyocera 135W panels and the Solar Boost 2000E today.
    I had planned to connect the two panels in series to reduce the wiring sizes and guessing that having the panels in series would reduce the impact shading will have on the performance. They will be mounted on a sailboat and will very often be partially shaded, and be at a variable, often bad angle to the sun. So, I really expect much less performance than under ideal conditions.
    Reading the 2000E spec sheet I realize that that controller only allows a max input voltage of 30V. The two panels in series will certainly be above this much of the time. But sometimes these max values are a little conservatively calculated, did any of you try (on purpose, or by accident) feed a higher voltage into this controller? I'd think most of the time my panels would be at 17 or 18 volts, so in series it would put me into the 34-36 range...

    Greetings, Stephan

  2. #2

    Default Re: Solar Boost 2000E input voltage

    Welcome Stephan!

    Maximum input voltage on any charge controller is just that: maximum. You don't want to go over it. But the good news is the panels are less effected by shading when in parallel, not series. If a shadow falls on one panel connected in series it reduces the output of the whole string - like having one low battery out of two in a flashlight. If they are parallel it effects just that panel. I shouldn't imagine you'd have particularly long wire runs on a boat, so line loss could be kept at a minimum fairly easily. See this thread regarding wire sizing:

    http://forum.solar-electric.com/showthread.php?t=29

    What's the rest of your system set-up? I'm guessing 12 V, and with those two panels in 'partial sun' you should be able to keep 135 A/hrs of battery happy, possibly more. Should be good for 400 Watt hours per day, +/-.
    1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  3. #3
    Join Date
    Sep 2006
    Location
    Willits, CA
    Posts
    5,692

    Default Re: Solar Boost 2000E input voltage

    Paper says 30V max. Sorry. Maybe trade with the vendor?
    Morningstar sun saver http://store.solar-electric.com/mosumpsochco.html
    is good for 75V.

    CAUTION!
    If you have panels in series, and one gets shaded (even a tiny bit), the output of
    the other panel will be cut too, or at lest in proportion of any panel bypass diodes.
    http://tinyurl.com/LMR-Solar
    http://tinyurl.com/LMR-BigLug
    http://tinyurl.com/LMR-NiFe

    Grundfos 10 SO5-9 with 3 wire Franklin motor (1/2hp 240V 1ph # 214505 ) on a timer for 3 hr noontime run - Runs off PV
    Powerfab poletop PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe battery | 15, Evergreen 205w "12V" PV | Midnight ePanel || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT

  4. #4

    Default Re: Solar Boost 2000E input voltage

    Cariboocoot,

    this is indeed great news. I hadn't realized that the panels in parallel are better. Oh, so cool! Some fatter wire won't be a problem, really. You are totally correct.
    The rest of my setup is currently three group 24 dual-purpose lead batteries in parallel, eventually to be joined by a fourth.
    Depending on the space available, I might try to make that fourth battery a group 27 or even 31. But I would ask you first if having dissimilar batteries in parallel would have unexpected bad side effects.
    This group is great! I didn't expect an answer, and such a good one, so quickly.
    Thanks again!

    Stephan

  5. #5

    Default Re: Solar Boost 2000E input voltage

    You will probably be disappointed with your battery choice. For one thing, "dual purpose" usually means "not as good as the proper thing in two different applications." If you want true performance out of your system, it's worth buying real deep cycle batteries of the "electro-motive" type: i.e. for golf carts and electric forklifts. The other thing that matters is the Amp/hr rating: too high and the panels don't produce enough current for proper re-charging (the experts recommend 5%-13% of the battery's Amp/hr rating for charge current). Too low and you don't have enough capacity to run anything or you'll be drawing them down too much. This is called "depth of discharge" (DOD) and it is recommended you keep it below 25% for most deep cycles. Really, really good ones can take 50% DOD repeatedly. So when calculating your usable power, you have to use 50% MAXIMUM of the battery's Amp/hr rating to see how much usable power you have: 100 A/hrs * 50% = 50 A/hrs @ 12 V = 600 Watt/hours. That's six 100 Watt bulbs for one hour, or one 100 Watt bulb for six hours. These are nominal calculations, and don't include the fine tuning that comes with calculating an individual system's particular efficiency losses (which can be substantial). But it gets you "in the ball park".

    Your 270 Watts of panels would also have to be 'derated' for efficiency losses and the (in your case) quite unpredictable amount of sun that will fall on them. It's easier for a fixed location, but even then there's seasonal differences. So figure roughly 60% capacity average over five or six hours of usable daylight. All in all, I'm thinking somewhere in the neighborhood of 200 Amp/hrs of battery capacity might be viable for your system. That would give you the 50 A/hrs mentioned above with lots of margin for error. But it's very imprecise.

    The other thing about batteries is don't mix different types; they don't discharge/recharge the same, and the end result will be premature failure of all the batteries.

    Now the "$64 question": what is your intended usage? It's important to know what you hope to get out of a solar power system before you can figure out what to put in to it. Too many people buy a "package" and then find out it's hopelessly inadequate and often seriously over-priced.
    1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  6. #6

    Default Re: Solar Boost 2000E input voltage

    Coot,
    thanks for taking time to look at my setup.
    My intended use is to power the boats electric system to a degree that running the engine to recharge can be reduced to as little as possible.

    My biggest power hog will be my fridge, which will possibly draw between 480-960 Wh per day. The good thing is that the fridge needs most power when it's day, and hottest, and that usually means it's sunny, so the panels feed immediately into the fridge.
    The rest of my consumption is mostly lights (some of them LEDs, all the rest low power (15W or 10W)), laptop computer (maybe 3 hours a day, 70 W), and the stereo (3 hours, 20W).
    So, a very rough estimate would be that I'd use between 1kWh - 1.5 kWh per day.

    My planned 4 batteries would have a nominal storage of
    75Ah * 4 = 300Ah * 12V = 3.6 kWh
    As you suggest, drawing them down to 50% is the absolute max I should do, better for long life would be to stay higher.

    On sunny days I think I might be fine with this setup, but on cloudy days, my engine will have to be used to recharge the batteries...

    Since I have the 3 batteries already, I thought it would be quite uneconomical to exchange them all for deep cycle at this time. I was thinking of doing this when they start losing capacity.

    I'm aware that, unless I seriously upgrade my battery bank, I'll live hand-to-mouth, so to speak. But still a step in the right direction, right?

    Greetings, Stephan

  7. #7
    Join Date
    Jul 2007
    Location
    Quetico, Ontario
    Posts
    5,025

    Default Re: Solar Boost 2000E input voltage

    Your 270 watts of panel will be lucky if they produce ~5-600 wh/day,, even if you keep them optimally aim,, tough to do on a boat.
    My rule of thumb,, is to take the name plate rating of the array,, (270) divide it by 1/2 to take into account ALL system losses,, (Panel ef, charge controller ef, basic battery charging ef, wiring losses, inverter efficiency etc>) that would make 135,, multiply this number by the expected hours of GOOD sun,, normally ~4 = 540 wh. If you go into this using 1-1.5 kwh/day, you will go into deficit right away. That coupled with non-deep cycle batteries,, and I would predict that you will have expensive lead ballast quite quickly.


    Tony

    PS, I that there is some quibble with my 50% number,, some think it too high,, some think it too low. The point is,, for a quick calc,, it is close enough to realize that in cases such as yours,, you are going to be in deficit regardless of if my number should be 55% or only 45%.
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

  8. #8

    Default Re: Solar Boost 2000E input voltage

    Remember: you haven't got 300 Amp/hrs to work with, you've got 150 MAX.

    Those panels are going to be marginal at keeping up with usage and recharging even that amount, especially given the unpredictability of your solar exposure. Any chance for adding more panels in future?

    And Tony is, as usual, right: panel ratings are peak ratings, not continuous. For an over-all average of actual usable power, serious de-rating is required. Although I use 60% rather than 50%, so I must be something of an optimist!
    1220 Watts of PV, OB MX60, 232 Amp hrs, OB 3524, Honda eu2000.

    Ohm's Law: Amps = Volts / Ohms
    Power Formula: Watts = Volts * Amps

  9. #9

    Default Re: Solar Boost 2000E input voltage

    Thanks Tony and Coot,

    I understand that I'm marginal to keep up with my electricity drain. I'm not expecting to be able to keep my engine off for good, but to reduce the number of hours I need to run it. I hope that by carefully monitoring the battery condition (the controller has a volt meter) I can avoid discharging them too much.
    I'm reducing my power use by increasing the fridge insulation and eventually getting a laptop with lower power drain. The LEDs are the only lights I run a lot of hours, all the other lights are on only infrequently. I have no appliances of any kind. So my hope would be to reduce my use to significantly less than 1kWh.
    I chose the MPPT controller hoping to get higher efficiency than a 'dumb' controller. The current that goes into the fridge compressor doesn't have to be stored, so I have no big loss with the battery. I don't have my inverter hooked up much, unless I'm charging my phone or the hand tools.
    Last not least, I might get another pair of panels eventually, I'll size my mounting frame accordingly. Unfortunately, the space on the boat is somewhat limited, just like my wallet.

    Greetings, Stephan

  10. #10
    Join Date
    Jul 2007
    Location
    Quetico, Ontario
    Posts
    5,025

    Default Re: Solar Boost 2000E input voltage

    Remember, Voltage is not a very good way of measuring battery condition. The only time voltage is anywhere near accurate is when the battery has been "at rest", neither charging nor discharging for several hours. While charging the battery will show artificially high,, while discharging low. A better way is to check specific gravity with a hydrometer, (not possible with sealed batteries) or use a good battery monitor like the Tri-metric that counts AH out/AH in and gives a real time state of charge.

    The reality is that the increase from the MPPT on such a system is likely to be under 10%, not insignificant,, but in your world not enough to make much difference.

    If you haven't already read these: http://www.batteryfaq.org/
    http://www.windsun.com/Batteries/Bat...of%20Batteries

    Tony
    Please note, being a moderator does not add any weight to my opinions 300 watts Siemens/BP panels,plus a Sun 90,, making ~400. ~30 amps into Rogue MPT-3024, 450 ah of Trojan T-105, Morningstar ts300 inverter, a Tri-Metric meter.a collection of antique generators, plus 2 Honda eu-1000i's (also a BS2512 IX controller) and assorted other stuff!

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