Renogy system question

[jdux999]

Hello All again. One of the more confusing topics for me is solar. Every time I think I understand it I find out that I don't. To start out I was thinking about a 100 -200 watt Renogy suitcase system. I'm assuming they come with a PWM controller but I'd rather have an MPPT controller ( I think). If I get the Renogy system can I replace the PWM with an MPPT and if so, is that all that's necessary or do I need to reconfigure other parts of the system? I have a Redhawk 26XD that has the solar prep package included. Thanks in advance for the help.

[cabinetmaker]

This is the one I have been eyeing. It’s on my short list. Has the monocrystalline solar cells. Very durable. Built in controller. It has the PWM you mentioned. Not sure if you could change that. Why do you want the MPPT?

[cabinetmaker]

Found this. Looks to me like the MPPT is made for larger systems. It is more efficient.

PWM

The PWM charge controller is suitable for small systems. It provides a low-cost solution and is normally used when the solar cell temperature is between 45°C and 75°C or 116f and 176f.

MPPT

MPPT system is normally used when the PV array voltage is substantially higher than the battery voltage. It is the best solution for higher power systems. The MPPT charge controller also provides substantially more power when the solar cell temperature is below 45°C or above 75°C, or when irradiance is very low.

[cabinetmaker]

Here’s the battery I am also wanting to go with the solar. Probably need at least 2 of these. Winter project!

[jdux999]

Hi Cabinetmaker. You're probably right, especially with the size of the single battery in my rig. Just get confused with the efficiency issues of PWM and the speed at which they convert to amps compared to MPPT. For now, I'll probably do what you're doing and stick with what's in the package. I didn't know Renogy sold batteries as well. I'll take a look at that as well. Having been in IT for 35 years, I'm a big advocate of single provider systems.

[Mustang65]

Originally Posted by jdux999

Hi Cabinetmaker. You're probably right, especially with the size of the single battery in my rig. Just get confused with the efficiency issues of PWM and the speed at which they convert to amps compared to MPPT. For now, I'll probably do what you're doing and stick with what's in the package. I didn't know Renogy sold batteries as well. I'll take a look at that as well. Having been in IT for 35 years, I'm a big advocate of single provider systems.

PWM vs MPPT!!

If you click on the RVing with SOLAR link below, there is a lot of information regarding batteries, SOLAR, mounting.... Get a beer, sit down, open the tablet connect to the RVing with Community and enjoy your reading. Make that 2 beers.

The basic reason why you get more out of an MPPT SOLAR Charge controller. Taken from the RVing with SOLAR community.
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\The old standard was Pulse Width Modulation (PWM) types. The newer Maximum Power Point Tracking (MPPT) controllers are even better. They match the output of the solar panels to the battery voltage to insure maximum charge (amps). For example (PWM): even though your solar panel is rated at 100 watts, you won't get the full 100 watts unless the battery is at optimum voltage.

With a PWM charge controller, if your batteries are low at say 12.4 volts, then your 100 watt solar panel rated at 6 amps at 16.5 volts (6 amps times 16.5 volts = 100 watts) will only charge at 6 amps times 12.4 volts or just 75 watts. You just lost 25% of your capacity!

The MPPT controller compensates for the lower battery voltage by delivering closer to 8 amps into the 12.4 volt battery maintaining the full power of the 100 watt solar panel! 100 watts = 12.4 volts times 8 amps = 100 (P=E*I).
------------------------------------------

So your probably asking, What does all that mean.
Easy description:
If it were possible (for this analogy only) to get 100% SOLAR panel output for the Average 5Hours of sunshine:
The PWM system would be able to produce 6Amps * 5Hours = 30Amp Hours to put back into your battery.

The MPPT system would be able to produce 8Amps * 5 Hours = 40Amp Hours back into your battery.

So, is MPPT worth the additional money... only you can answer that question! Especially when you are looking for a few more Ah's at the end of the day.

Even with smaller systems MPPT still is better. I love mine!
Don

My Registry

RVing with SOLAR

[jd99336]

Mustang has given excellent advice. I recommend you try PWM first. If you are only charging one battery for occassional use, you will likely find it more than enough. I have not used mine formally yet, but am using a PWM system (200W) simply because I want something to push me over the hump when dry camping for 3 days or more. If I end up in deficit, I will use the generator. Good luck and have fun with it.