mppt vs pwm

It should also be pointed out that MPPT controllers are also (usually) the ones that offer other features, like battery equalization and long term maintenance. Most PWM controllers, especially the ones being touted as cheap, are simply chargers.

In my controller, MPPT is used in the bulk stage only since once you get to the absorb and float stages the battery voltage is high enough and the battery acceptance rate is low enough that MPPT isn't needed and the extra amps wouldn't go into the battery anyways.

The buck converter is always active even in float which is good. At altitude each of my three panels produce a Isc of around 10a but I can pull a load of close to 50a without pulling the battery out of float.

"Do mppt controllers operate in mppt throughout the entire charge cycle, or just during bulk/cc?"

Need to know what you believe MPPT mode is....

If it's the tracking algorithm that attempts to obtain the Vmp from the array - then the answer is that it DEPENDS. Some of the Blue Sky MPPT Controllers have only a Potentiometer that the user is required to set and forget (IMHO at best a joke the Vmp varies a lot and the pot is inside the controller). Another answer is mostly yes the tracking algorithm is active most of the time for higher end controllers.

Many controller show "MPPT" as one of the operational modes - it's simply there to help the user understand that the available lighting conditions are making it difficult for the controller to obtain and hold a Vmp setting.

As for the buck conversion stage again it depends
If the panel voltage is higher than the desired battery voltage them it is always functional - some proper controllers bypass the buck conversion stage if the battery voltage gets close the array voltage

Do mppt controllers operate in mppt throughout the entire charge cycle, or just during bulk/cc?

My three series panels have 62' of 10ga wire to the controller. Parallel panels would cost more for 4ga wire, combiner box and fuses.

Outback presented MPPT as an anwer to extremely long cable runs first and foremost even using lower voltage panels. There weren't high voltage panels then. Series connect low voltage panels then save a considerable amount of money on wire. Many systems use 100+feet wire runs. One commercial system down here uses 380 vdc arrays.

Thanks PT, I very much appreciate his logical presentation.

3 tons

MPPT vs PWM Cost Comparison for 700Wish System

Solar Blvd Panels, Solar Home Morningstar Controllers, Flat Install

5x140W $159 = 700W $795 plus TS45 $140, Total 700W $935

3x245W $196 = 735W $588 plus MPPT45 $370, Total 735W $958

And

7x140W $159 = 980W $1113 plus TS60 $207, Total 980W $1320

4x245W $196 = 980W $784 plus MPPT 60 $472, Total 980W $1256

It still boils down to what fits on the roof. Adding a extra panel to a PWM system may net you more for the money than switching to MPPT. Also this is a test of peak only. The difference side by side for a whole day would tell more. The same is true with mono vs poly, 12v vs 24v, etc.

Hi KJ,

Only one reason for MPPT with 17 volt panels. Lack of room for additional wattage.

Cost benefit needs to be done before making the choice to go MPPT.