MPPT.. hows it gonna work for me..

ywhic

After much trials and tribulations.. I am leaning toward a 12v battery bank of 330-440ah size..

I could keep my TS45 PWM controller and get my 6 panels parallel and 870 STC panels on it, be at 669w and 48.3 amps.. I avg 112w in my testing of 1 panel so 669w works.. no problems and done.

I decided I may just upgrade to the TS60 MPPT version of the same and reuse my TS meter.. (undecided).. or I may do the Midnite Classic 150 and have about 30 more amps above the 60 amp limit of the TS60 (above)..

I was going to go with the Rogue.. but the cap on that is 30 amps.. I'll be at 24v and 24v going that route as I can do upto 870 safely with a 24v bank.. but not a 12v bank..

Anyway.. I want a 12v battery bank.. I got the 3/0 wire and fusing here as that was my intent 3 months ago when I started this mess of a project..

The numbers at 115' ambiant for my panels when done 2 in series is 32.796 VMP.. per the calcs from Midnite and MS websites.. all work out to about 780-790 watts vs. my lowly 669 with PWM controller.. and I was told I may only see single digit gains by Rogue (thanks Marc).. I'm thinking year round usage.. so MPPT will still be better.. and in my boredom today I figured 33.92VMP at 85F, 34.3VMP at 75F, & 35.06VMP at 55F..

The 12v bank is pretty much set as Xantrex is still making the SW 2000 ProWatt (per a phone call 2 weeks back to them).. so for $330 I will have a 2000W pure sine inverter.. which tested by 2MANYTOYS seems to be the A/C running winner for my TX project.. if later the 12v inverter dies and I have the cash I can get a 24v inverter and just switch some wires and settings..

Now.. my question is..

Based on a 24v system setup with 3 parallel sets of 2 panels.. (aka 36 VMP and 43.3 VOC).. I'll be pumping 24 amps into the controller (8 IMP * 3 sets = 24 amps)..

Then when in MPPT mode it will convert to 12v and adjust the amps UP for the xtra volts from the panels..

The TS 60 MPPT says I will be at the LIMIT for the controller like this for 12v battery bank.. does that mean I would expect up to 60 amps after conversion using the MPPT controller???

And do you think using the Midnite Classic 150 would yield higher AMP numbers than the MS TS60 MPPT??

What numbers could I expect from 32.796 VMP (at 115'F) and 8.05 IMP panels into a 12v bank?? Would it be 264 watts * 3 (number of parallels).. which would be 792 watts, which would be 91% eff??

Anyone have the TS60 MPPT and run 24v panels and 12v bank that has a screen shot would be appreciated..

SolaRevolution

Re: MPPT.. hows it gonna work for me..

ywhic wrote: »

The TS 60 MPPT says I will be at the LIMIT for the controller like this for 12v battery bank.. does that mean I would expect up to 60 amps after conversion using the MPPT controller???

Yes. After conversion.
The TS 60 MPPT is rated for 60amps output.
If battery voltage is low, say 12.5v, the CC's output is limited to 12.5v X 60amps = 750w.
If it is higher, say 13.5v it is limited to 13.5v X 60 amps = 810w.

The only times you will be "losing" available PV power will be during the prime sun hours 10:am-2: pm when you have clear skys, cool ampient temps and the batteries are low. If the it is not peak-sun hours, if the sky has any haze or overcast your array will not be putting out full potential anyway.

ywhic wrote: »

And do you think using the Midnite Classic 150 would yield higher AMP numbers than the MS TS60 MPPT??

The Midnite Classic 150 would be able to harvest your PV arrays peaks better than the TS 60 MPPT. How much difference in real wattage is hard to quantify. With numbers this close I would base the purchase decision on other factors such as support, data logging options and convenience of programming.
(Also, it's hard to beat black art deco for the cool factor)8);)

-Alex

ywhic

Re: MPPT.. hows it gonna work for me..

SolaRevolution wrote: »

Yes. After conversion.
The TS 60 MPPT is rated for 60amps output.
If battery voltage is low, say 12.5v, the CC's output is limited to 12.5v X 60amps = 750w.
If it is higher, say 13.5v it is limited to 13.5v X 60 amps = 810w.

The only times you will be "losing" available PV power will be during the prime sun hours 10:am-2: pm when you have clear skys, cool ampient temps and the batteries are low. If the it is not peak-sun hours, if the sky has any haze or overcast your array will not be putting out full potential anyway.





The Midnite Classic 150 would be able to harvest your PV arrays peaks better than the TS 60 MPPT. How much difference in real wattage is hard to quantify. With numbers this close I would base the purchase decision on other factors such as support, data logging options and convenience of programming.
(Also, it's hard to beat black art deco for the cool factor)8);)

-Alex

So that 13.5 number would be my FLOAT setting and the 14.4 or 14.6 would be my absorb setting correct?? (flooded no frills battery)

SolaRevolution

Re: MPPT.. hows it gonna work for me..

ywhic wrote: »

So that 13.5 number would be my FLOAT setting and the 14.4 or 14.6 would be my absorb setting correct?? (flooded no frills battery)

Yes, those might be the voltage set points, but once you reach the absorb setpoint you are no longer charging with all available current. You are really only using full current while in bulk (before the battery voltage reaches the absorb setpoint). After that, the charge controller throttles back the current in order to maintain the voltage at or below the setpoints.

-Alex

ywhic

Re: MPPT.. hows it gonna work for me..

I'm thinking a 550-650 watt/hour Air Conditioner would make the voltage drop abit.. LoL..

Eric L

Re: MPPT.. hows it gonna work for me..

I'm thinking a 550-650 watt/hour Air Conditioner would make the voltage drop abit.. LoL..

Yeah the surge on that is going to really pull the voltage down which is one of the reasons why going with a 24 volt system, if at all possible, is really likely to make your life easier since it's going to make the system more forgiving of voltage swings with the heavy draw.

You mentioned the Classic 150, but I'm guessing you saw the new Classic Lite 150 which has the same capacity but fewer frills for less $$$? NAWS was just running 5% off which get you a very powerful and flexible Classic Lite at under 500 clams.

Among the advantages of the MPPT, let me throw in another. Let's say you're in your new house and find you almost have enough power to run the AC and charge your batteries, but not quite. With an MPPT style controller, especially one that can accept a high input voltage like the Midnites, it's likely to be easier to make incremental additions to your array. Maybe you'll find that you eventually want, say, eight panels, which you could wire into two series strings of four with the MPPT controllers (most of them at least). With PWM controllers, you'd have four series strings of two at 24 volts (eight strings at 12 volts); a lot more wiring and fusing to buy.

ywhic

Re: MPPT.. hows it gonna work for me..

I played with some numbers on the Midnite Solar website.. using the 150 Classic numbers..

Got upto 8 panels with a 12v battery bank.. Got upto 10 panels with a 24v battery bank.

The MS Tristar 60 MPPT is good for only 6 panels in 3 strings of 2, or 2 strings of 3, or 1 string of 6..

If I can sell the TS45 and the meter I will have about $200 going toward the Classic.. so upgrade is about $410 ($610-200)

If I only sell the TS45 and not the meter.. I will have about $100.. I may just grab the TS-60 MPPT upgrade for $360 ($460-100)..

I'm hoping I sell both as I would prefer the Classic with the meter/graph front..

vtmaps

Re: MPPT.. hows it gonna work for me..

ywhic wrote: »

I am leaning toward a 12v battery bank of 330-440ah size..
<snip>
And do you think using the Midnite Classic 150 would yield higher AMP numbers than the MS TS60 MPPT??

Yet again you have changed your mind! It looks like you hope to push more than 60 amps into those batteries. That's a lot of amps for that size battery, especially so if the battery is hot.
--vtMaps