MPPT Charge controller

[Sandwagon]

I have just purchased two very cheap solar panels at 190w (grape solar 190w panels) each.

My question is: will I be able to get the full wattage out if them with a TS-45 MPPT Charge controller?

The reason I ask is because the panels are rated at 36 volts 5.25 amps which is around 190w. I'm currently testing them with a TS-45 pwm charge controller on a 230 amp 12 volt battery system. Because they are only rated at 5 amps all I am pulling is 60-80 watts on each panel in direct sun light. I believe this is because they are rated at 5 amps? I'm still very new to all of this so please bare with me.

Again my question is will I be able to get close to 180w from each panel (300-360w total) if I use a TS-45 MPPT charge controller instead of the TS-45 PWM charge controller on this set up? Thanks.

Jesse

[tedgard01]

Hey, no idea. Regardless, I'll follow your post since I'd like to add some solar panels to my RV as well.

I hope that they would at least keep my house batteries charged or help run the heater in the winter.

[vsheetz]

This should be working ok.

You have the two panels wired in parallel, correct?
Is the system voltage in the TS45 set to auto or a fixed voltage - if fixed what voltage?
How are you knowing the amps - you have the digital display for the TS45?
If just one panel at a time, are they about the same?
You are tilting so directly at the sun on a very clear day?

[Dunner]

Give these guys a call.

Solar electric power components and solar panels

[Sandwagon]

I am using the bogart battery monitor to monitor what is going in and out.

Yes, they are wired in parallel.

I tried both automatic and the manual setting at 12 volts with no change in the amount of watts or volts going into the batteries. The closer the batteries are to being topped off the higher the volt reading and watts go up as expected.

Both panels are the same when checking them one at a time. About 70 watts each pointed directly at the sun. They are rated at 36 volts instead of the normal 18 volt panels typically used for a 12 volt system. I have also checked the panels on a 24 volt system and got over 300 watts from the panels so I know they are putting out what they are rated for.

I have 380 watts of solar and was hoping I would get close to that if I switch to a MPPT charge controller. Does anyone know if by using an MPPT controller that I will be able to accomplish that with the higher voltage panels going to a 12 volt system? Thanks.

[John Hilley]

If you are getting 5 amps out of the panels, 5 x 36 = 180 watts.

[Ed-Sommers]

MPPT is the only way to go if your battery bank is wired for 12 volts. Not only does MPPT provide advanced charging (mainly at higher battery discharge), it recognizes input and battery voltage and converts one to the other!

Ed

[vsheetz]

In re-reviewing this senario, the PWM controller will not make full use of the panels. About half the wattage will not be realized. Some possible options, depending on the goals and economics: Swap the 190w panels for 3-4 ~100-120w 12v panels, use as is if you got the panels really cheap, opt for the MPPT controller.

Myself, I have a TS60 PWM with several used 100w panels via Craigslist - works great. Multiple physically smaller panels give installation flexibility and shading mitigation.

[Tony Lee]

A pulse width modulated controller running from 24V panels into a 12 volt battery is essentially wasting half of the output of the panels because it has no way of transforming 24V at 5 amps into 12V at 10 amps which is what a decent MPPT controller can do. I'm using 12 and 24 as nominal voltages even though in practice they may be much higher (or lower) under certain conditions

Other things to consider is that solar panel specs are quite misleading unless you are aware of how they are measured. It is exactly like a centrifigal pump that might be rated at 3000gph 100psi doesn't mean it will deliver 3000gph of water at a head of 100psi. It is either - or, not both at the same time.
With solar panels the rating is amps under short circuit conditions ie zero volts OR volts under open circuit ie zero amps. Just to confuse the ussue even more is that often figures are given for amps and volts at maximum power production and in this case you can multiply them together to give maximum power watts (which will never be as much as the nominal power rating of the panel (another story). This maximum power output can in theory be utilised almost fully by an MPPT controller which can electronically act in a similar way to an AC transformer which with the right winding ratio, halve the voltage while doubling the available current. THe PWM controller can't do this but acts more like an AC autotransformer with a single tapped winding which can reduce the output voltage but can't boost the current.

Pretty big topic and a fully technical discussion would be long and over my head anyway.

[bdosborn]

Originally Posted by Sandwagon

Again my question is will I be able to get close to 180w from each panel (300-360w total) if I use a TS-45 MPPT charge controller instead of the TS-45 PWM charge controller on this set up?

Your 36V panels aren't set up to charge 12v batteries with a PWM controller. They're really grid tie type panels and as you noted, aren't at a typical 12V battery voltage.

This is the output power of your panels when they are operated at the maximum power voltage:
36V*5.25A=189 watts

Your PWM controller operates the panels at 14.4V (battery charging voltage), which is way outside the peak output curve of the panel.

This is what they put out out as you have them configured:
14.4V*5.25=75.6 watts

A MPPT controller will operate the panels at 36V and convert the output to 14.4V to charge your battery. You should get closer to the panels rated output with MPPT.

You could then configure your panels to run in series if you wanted to but I wouldn't. 8% shading on one panel will reduce the total output of both panels by 94% when they are in series. Shading on one panel only affects the shaded panel if they are in parallel. You'll get full output from the unshaded panel. I have multiple panels on our RV and its amazing how many times there's a shadow on one of the panels.

Bruce

[Sandwagon]

Thanks for all the help. Looks like I'll be buying a new charge controller.

[jackfish]

The Morningstar TS-45 MPPT is a good charge controller.