2 Uni-Soloar PVL-128 need charge controler

heythorpheythorp Registered Users Posts: 10
I read everything (or so I thought) for 3 weeks. Found the Uni-Solar panels cheap and they meet my flexibility needs.

So ordered the panels and then started doing more reading. Oh crap, stuck in newbie corner.

I just wanted about 120 watts to charge a batter, but the panels where so cheap I was like yeah, grab 2 and add a battery, no biggie right?

Wrong. I knew I was going to need a 24v charger, but I did not check the number close enough. Many chargers won't handles these 2 panels (at least the cheaper ones) I don't mind having a 24v system, but 12 makes things a lot easier/cheaper.

I am just creating a small semi mobile system for charging needs and back up at home if I need to run the refrigerator for an hour or 2.

Specs on the panels:

Rated Power (Watts) 128
Nominal Operating Voltage 24
Operating Voltage (Volts) 33.0
Operating Current (Amps) 3.88
Open-Circuit Voltage (Volts) 47.6
Short-Circuit Current (Amps) 4.8
Series Fuse Rating (Amps)* 8
Min. Blocking Diode (Amps) 8

Seems like I am going to need an MPPT, but its such a small array I was hoping there is something out there that will work that I missed.

Can anyone recommend a charger that can handle these 2 panels and an inverter that is minimum 2500 watts 12v?

Thanks for the help. I just can't read anymore, I have not slept in weeks.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Welcome to the forum.

    Sorry, but I can't think of a single small Amp MPPT controller that can handle the Voltage of those panels. By the time you get one that can, you're at the $400+ range and 45+ Amp controllers (MS MPPT 45 @ $419). Maybe you could find a used one for cheap. Or flog the panels and start again.

    Speaking of which, you won't be very happy with a 2.5 kW 12 Volt inverter. And inverters do not run from charge controllers, they run from batteries. The panels and controller are to recharge the batteries. So the first thing you need to do is figure out how much power you have to supply. For running a refrigerator, that's not going to be a low number. I just tested a few. They have pretty high start demands and they chew up the kW hours daily; anywhere from 1.2 on up to 3.0. You can test yours with a Kill-A-Watt. It won't get the start surge but it will give you the Watt hours.

    And when you get that number and divide it by 12 Volts and find out you need 200+ Amp hours of battery and around 400 Watts of panel to recharge ...

    Time for a rethink. :roll:
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 2 Uni-Soloar PVL-128 need charge controler

    The MorningStar 15 amp MPPT controller (12/24 battery bank) should work.

    And, the Rogue 30 amp MPPT (also 12/24 volt battery bank support) probably will work too.

    Both sets would require you to run the panels in parallel (they are pretty close on the Vmp of 33 volts for a 24 volt battery bank--especially if you are in hot weather).

    Take a look at see what you like/don't like about these two controllers (both are very good MPPT charge controllers).

    And, I agree with Marc, a 2,500 watt inverter is too big for this size of solar array. Do you really need that much power? Or can you get away with 300 watts.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • heythorpheythorp Registered Users Posts: 10
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Thanks MODS!

    Hey BB I am in Redwood City.

    I think I read about those 2 controllers and I was thinking about the Morning star but I was worried about my open current load. But it looks like I would be OK if, like you said run them in parrellel as max open current is 75 volts.

    electrical
    • Peak Efficiency 97.5%
    • Nominal Battery Voltage 12 or 24 volts
    • Max. Battery Current 15 amps
    • Battery Voltage Range 7-36 volts
    Max. PV Open Circuit Voltage 75 volts
    • Nominal Max. PV Input
    12 volt battery 200 Watts
    24 volt battery 400 Watts
    • Output Rating 15 amps load control
    • Self Consumption 35 milliamps
    • Transient Surge Protection 4 x 1500 Watts


    Clearly still learning and all of my electronic classes from high school are not helping 20 years later.

    I don't need that much power, but I was being overly cautious. Do inverters pull their rating the whole time or just as much as is being requested?

    Plus while refrigerators do pull about 3KW a day, they don't run constant. So If you if I could get a few cycles out of a battery bank that would be good.

    Also I will be putting in a small wind generator at some point.

    Thanks


    Oh and know anyone who wants a couple PLV 128 panels ? ;)
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Hi from the City of San Mateo (near Hillsdale Shopping Center). :D

    The Rogue is rated at 60-volt Voc maximum... So, it should be OK with the Uni-solar panels too.

    Larger inverters can consume 20-60 watts of power with zero load on them.

    And there is the whole question of Modified Square/Sine Wave inverters vs True Sine Wave Inverters.... Some reading here:

    All About Inverters
    Choosing an inverter for water pumping

    Generally, TSW is better for some loads (small wall mounted transformers, some induction motors, some electronics). However, they tend to have higher "tare" losses (when on and no-load).

    MSW are a form of square wave which can create waste heat in motors (upwards of 20%) and some electronic power supplies may die in minutes or days.

    For the most part, about 80% of loads will run fine on MSW and 10% will not--And it is not easy to guess which will or won't.

    I would suggest for emergency power (or small cabin), you look at a 12 volt 300 watt TSW inverter from MorningStar (600 watt surge). It has some nice features that you do not often find on small inverters. A "search mode" (which reduces stand by current) and a remote inhibit input (low voltage/low current on/off switch).

    If you need a larger inverter--You can get a second "cheap"/large MSW inverter (power tools) or -- usually a better bet for random usage--a nice genset (Honda/Yamaha inverter generators are pretty fuel efficient but expensive to purchase). The Honda eu2000i will power ~400 watts for almost 10 hours or 1,600 watts for 4 hours on ~1.1 gallons of fuel (plus you can make a siphon external fuel tank for 5+ gallons of fuel at a time instead of the internal 1.1 gallon tank).

    Or a big old 5kW noise maker. Will work OK in emergencies--but use so much fuel as to be almost worthless in a multi-day power outage (many gallons of gasoline per day). A typical fuel spec. may be:
    • Fuel Tank Capacity (Gal): 7.20
    • Fuel Tank Capacity (Ltrs): 27.25
    • Run Time at 50% (Hours): 10
    So, 2.5 kWH for 10 hours on 7+ gallons of fuel.

    And most simple gasoline gensets do not use much less fuel (GPH) at less than 50% load.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • heythorpheythorp Registered Users Posts: 10
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Thanks for the info. I have read for days about inverters, but still need to read more.

    Would this work for me?

    http://www.ebay.com/itm/XANTREX-C35-SOLAR-Charge-CONTROLLER-35-Amps-12V-24V-/360387764308?pt=LH_DefaultDomain_0&hash=item53e8c8e054
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 Uni-Soloar PVL-128 need charge controler

    The Xantrex C35 is not an MPPT controller; it won't down-convert the higher panel Voltage to a 12 Volt system.

    The Rogue (which I forgot about :blush: ) is the best choice here, as the MS 15 MPPT is marginal on the Watts (recommended to use 200 Watts for a 12 Volt system; the two panels you've got would be 256).
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 2 Uni-Soloar PVL-128 need charge controler

    If you plug all of the efficiencies together for the small MorningStar, you can support (cost effective maximum):
    • 15 amps * 14.5 volts charging * 1/0.77 system derating = 282 watts
    The controller will work with more wattage--but during cool mid-day afternoons, the controller will limit its output to ~15 amps maximum (charge controller losses, solar panel derating of marketing number, hot panels generate less power in full sun and warm weather, dust on panels, aging, etc.).

    That is different than PWM controllers where if you have too large of array current, it can cause the controller to overheat and shut down.

    But, in any case, the Rogue is also a very nice cost effective smaller controller too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Especially as expansion is inevitable. :p
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 2 Uni-Soloar PVL-128 need charge controler

    And beware--Expansion is not easy with solar PV systems... You should really plan ahead of time what you will want to expand.

    If you over double the size of the system through expansion, that tends to require higher battery bank voltage, which requires a new inverter, which may need a new/larger solar charge controller, which will need new panels which may not mix with the old panel specifications, etc...

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • heythorpheythorp Registered Users Posts: 10
    Re: 2 Uni-Soloar PVL-128 need charge controler

    These panels are interesting and I was really only going to get one to use as a take with me sort of package. I rent so the system is not going to be getting bigger. These will not be mounted traditionally and might even be taken down each day.

    Maybe I will just use one panel and try to sell the other. Even still that open current of 47V is the real issue.

    These panels pulled 42 v with indirect sunlight and 33 with paper cover the entire panel.

    I probably should walk away from this project but these panels interest me so much.

    I don't even have a system running and I am hooked. Big trouble

    Thanks for the great information. You guys really support this cause greatly.
  • heythorpheythorp Registered Users Posts: 10
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Yes I am looking for a cheap solution. As I was about to buy the morning star I decided to check out this website.

    I found this guy "BZ Products MPPT250". It looks like it should work. There is zero room for growth but that is ok. I understand this is not one of the "good" brands (morningstart outback, xantrex).

    BB you said my watts are 256 right? but that's ideal and will never really get there. The stats on this say max 250 watts.

    If this will work. Does it matter which one? $10 difference. Depending one which one I get will depend on series or parallel. Thanks as always



    BZ Products MPPT250
    .......................................MPPT 250............................. MPPT 250 HV

    Charge Current ............. 25 amps continuos..................25 amps continuos
    Surge Current.................35 amps for 10 minutes............35 amps for 10 minutes
    Array Voltage Open Circuit..........50 volts.........................100 volts maximum
    Max Imput Power....................250 watts........................250 watts
  • BB.BB. Super Moderators, Administrators Posts: 32,007 admin
    Re: 2 Uni-Soloar PVL-128 need charge controler

    Oh, oh... A BZ controller.

    I have not seen any recent testing, but a couple years ago some BZ product was looked at (and purchased) by a few people here and found to be pretty much worthless as a MPPT charge controller.

    Here is one old thread from 2007:

    BZ Controller thread

    I have not read any good news here yet about any present production BZ controllers.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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