Should I use a mppt500 or mppt500hv ?

3 Posts
Dec 26, 2011 10:35 pm
Should I use a mppt500 or mppt500hv ?

I am building a small off grid system using two 230 watt panels.
They are 34 volts open 8 amps each, BP 3230T. I can wire them
In parallel or series.  The battery bank is (4) Trojan T105 series-parallel
For 12 Volts.  My inverter is 3000 watt Heart.  Will use for TV, small
electronics, lights, and other items as used in a weekend cabin.  The panels are Pmax 29.1V,  Current @Pmax 7.9A,  VOC 36.7V, Nominal is 20V.    I have      access to either of the following controllers.  MPPT500 or MPPT500HV.

Should I use a BZ MPPT500 or the HV version,  to maximize wattage to

batteries?  Series or parallel the panels?  25 ft run to panels.


« Last Edit: Dec 28, 2011 04:48 pm by lj gwen »
65 Posts
Dec 28, 2011 05:49 pm
Re: Should I use a mppt500 or mppt500hv ?

Hi LJ,
It's been a year or three since we've sold the BZ Products MPPT 500 controllers, and  I'm not sure of their voltage limits. I *think* the normal MPPT 500 had an upper limit of 100V DC and the HV (High Voltage version) ... 125V or 150V?

If the open voltage of those panels are 34V then definitely you won't be able to use more than 2 in series  (which is what you have) with the MPPT 500.  If it get really, really cold where you live (say -20F or lower,*I'm super rough guessing*) it's possible that the Open Circuit Voltage for the two of them in series would increase to beyond the upper limit of the normal MPPT 500.  If these low temps are possible then you may as well just opt for the  high voltage (HV) version just to be safe.

I'm not sure if I understand your question about "maximize wattage to storage batteries". Can you clarify what you are looking for? 

There likely is no power efficiency gain by using the MPPT 500 versus the MPPT 500HV. Just one can take a higher voltage input than the other. Both are limited to their maximum current (amperage) output.

Putting those panels in series means you can use thinner wire on the input side to your controller. That'll save you money. You could put them in parallel and get the same efficiency but you'd have increase the wire gauge.

Last but not least, like I mentioned in another posting about MPPT controllers and high voltage - please be careful. Once you get beyond 48V DC you get to voltages that can stop an adult human heart. That could be a reason to just go with the panels in parallel (keeps your max voltage down to 34V).

Hope that helps!

"Making Renewable Do-able" (tm)
3 Posts
Dec 28, 2011 07:32 pm
Re: Should I use a mppt500 or mppt500hv ?

Thanks for the reply..... I guess what I meant by maximimize charge
to the batteries, was best controller to stay up with loads on batteries.
I assumed there was a different programming between the two
mppt500 and mppt500HV controllers. I bought the controller from
an ex dealer and he emailed me and asked which I wanted, the std
or the hv.  I read the specs on your site which showed the mppt500
had a max input of 100 volts, but on another site the mppt500hv
said "Model MPPT 500HV operating efficiency has been optimized
    for 48v nominal PV Input voltage."
My panels say 20volt nominal voltage each.  Do you think I should series them and go to the HV that is optimized to 48v or just stay with the standard MPPT 500 and series the panels?  We will not
have the panels in lower than 32 degrees F.

I am not commiting you to this... just want your experienced opinion.....

Thank You

65 Posts
Jan 3, 2012 05:12 pm
Re: Should I use a mppt500 or mppt500hv ?

My thoughts would be to go with the HV version (giving you plenty of breathing room for high voltage) and to to series the panels in 2's to take advantage of the thinner wire gauge you'll be able to use.

"Making Renewable Do-able" (tm)

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