Would like some input regarding proper charge control selection for stand alone and grid tie systems. Equipment location is sunbelt region with summer temps in the 90s to 100 degrees typical. Any Thought on this? Thanx, Richard
Comments
Richard,
Thank you for the question. It's good to do some research before purchasing anything. As this is a frequently asked question, we have published some information. There are similar questions to this question - you can see them on the right hand side.
Thank for your response. The question was generic in nature but I just completed 775watt off-grid system that will be used on weekends. Job was price sensitive and used PWM control. However when customer uses system, he will draw deeply from batt bank. My understanding is that MPPT would yield greater harvest. That leads me to believe that MPPT is better suited to off-grid apps. whereas grid-tied w/ batt b/u would lend itself to using PWM control since battery voltage is faily constant. Assumes sell voltage for this system is around 27.2volts. I could be completely misunderstanding the two technologies but it appears that the deeper the discharge, the greater the advantage of MPPT is. Could you expand on this? Thanx, Richard
There is clearly an advantage in using an MPPT charge controller. Especially in deeper discharged batteries and charging under time-constraint, I would definitely suggest a MPPT charge controller. I would use a MPPT charge controller for an offgrid project over 750W.
However, for one or two low voltage solar panels for not so critical applications (eg. solar water pumping) I would use a PWM charger just because it's much cheaper.
Example- Sunsaver PWM charge controller vs. Sunsaver MPPT charge controller price difference is almost 3 times. And the 24V Sunsaver PWM charge controller has a max. input voltage of 44V, which is sufficient for your system.
Of course, the industry is going to get rid of PWM chargers (just like you can't find shunt controllers in the market anymore) because of clear advantages and reduced prices of MPPT. But, it's beneficial to make a price/need comparison for the system you are building.
Great feed back! Thank you. I set a Xantrex C60 for the off-grid for expansion but will weigh performance above first cost. MPPT will be my control of choice regardless of off or off-grid apps. thanx again.
Comments
Richard,
Thank you for the question. It's good to do some research before purchasing anything. As this is a frequently asked question, we have published some information. There are similar questions to this question - you can see them on the right hand side.
And there are some related articles:
How to Size a Charge Controller
How do MPPT charge controllers work?
You can use a PWM charge controller if the size of your array is limited, because there is voltage limitations on PWMs.
MPPT -though it's more expensive- would provide you more output and would get more input voltage.
Feel free to check some of the charge controllers at Greentech Renewables.
Tell us about your system and I'll try to give some suggestion.
Thank for your response. The question was generic in nature but I just completed 775watt off-grid system that will be used on weekends. Job was price sensitive and used PWM control. However when customer uses system, he will draw deeply from batt bank. My understanding is that MPPT would yield greater harvest. That leads me to believe that MPPT is better suited to off-grid apps. whereas grid-tied w/ batt b/u would lend itself to using PWM control since battery voltage is faily constant. Assumes sell voltage for this system is around 27.2volts. I could be completely misunderstanding the two technologies but it appears that the deeper the discharge, the greater the advantage of MPPT is. Could you expand on this? Thanx, Richard
There is clearly an advantage in using an MPPT charge controller. Especially in deeper discharged batteries and charging under time-constraint, I would definitely suggest a MPPT charge controller. I would use a MPPT charge controller for an offgrid project over 750W.
However, for one or two low voltage solar panels for not so critical applications (eg. solar water pumping) I would use a PWM charger just because it's much cheaper.
Example- Sunsaver PWM charge controller vs. Sunsaver MPPT charge controller price difference is almost 3 times. And the 24V Sunsaver PWM charge controller has a max. input voltage of 44V, which is sufficient for your system.
Of course, the industry is going to get rid of PWM chargers (just like you can't find shunt controllers in the market anymore) because of clear advantages and reduced prices of MPPT. But, it's beneficial to make a price/need comparison for the system you are building.
Great feed back! Thank you. I set a Xantrex C60 for the off-grid for expansion but will weigh performance above first cost. MPPT will be my control of choice regardless of off or off-grid apps. thanx again.
Richard CHEERS!