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Old 21-03-2013, 08:18   #1
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MPPT vs PWM Solar Charger Controllers

Hello:

I am planning on adding solar panels to my boat and I wonder if an MPPT Charger Controller is worth the extra cost compared to a PWN type controller? It appears I am looking at 3 times the price for MPPT which is a heavy premium for what I believe is a 20% boost in output.

Also, what brands of each type are suitable for a marine environment and is there anything I should be aware of?

Initially I will just add 100W but I expect that may increase to as much as 250W. What size of controller should I plan on for to support this output?

At this time, I only have 2 flooded batteries but will increase that to 4 as my needs grow.

Thanks for any help you can provide.

Andrew
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Old 21-03-2013, 08:24   #2
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Re: MPPT vs PWM Solar Charger Controllers

You may wish to read thru this thread
PWM VS MPPT TROPICS
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Old 21-03-2013, 15:41   #3
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Re: MPPT vs PWM Solar Charger Controllers

If you have space on your boat for more solar panels, and am not planning on using higher voltage panels, then it is a much better bang for the buck to use the PWM controller and get more watts.

I.E. you will get more power from 2 140W panels and a PWM controller, and probaly spend less, than you get from 1 140W pnale and a MPPTcontroller.

But if you can get larger panesl that are lower cost/watt it gets less clear. I recently with the larger panel and MPPT.
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Old 21-03-2013, 15:54   #4
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Re: MPPT vs PWM Solar Charger Controllers

Ya, the prices on the large panels have come down a lot where they are sometimes the same price as half the Wattage in smaller panels. But those panels are big and would be a challenge to store if required while underway.

Where did you mount yours?

Andrew
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Old 21-03-2013, 16:01   #5
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Re: MPPT vs PWM Solar Charger Controllers

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Originally Posted by ADMPRTR View Post
Ya, the prices on the large panels have come down a lot where they are sometimes the same price as half the Wattage in smaller panels. But those panels are big and would be a challenge to store if required while underway.

Where did you mount yours?

Andrew
I'm putting mine above the aft part of my bimini with the front attached to that great Hunter traveler arch

I feel the answer to your question all comes dow to how much solar you need. If you can get by with 100W (I would get the 140W ones instead) then why use a MPPT controller? A 140W 12V panel with a PWM will out produce a 100W panel with MPPT controller. And everything I read is that is real boat use only expect the MPPT to get you 10% improvement.
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Old 21-03-2013, 16:08   #6
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Re: MPPT vs PWM Solar Charger Controllers

Ya, I tend to agree with your assessment.

As for placement, not having the arch I have to be more creative in my placement. I am actually playing with the idea of having them over my dodger so it won't affect the look of the boat too much. The question there is shade from the boom.
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Old 21-03-2013, 16:12   #7
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Re: MPPT vs PWM Solar Charger Controllers

To me the big advantage to the MPPT controllers is the voltage conversion. It means you can use 60, 66, 72, 84, or 96-cell modules rather than being restricted to the 32 or 36-cell (12V systems) that you have to use with a PWM controller. And it gives you the ability to connect the modules in series, leading to smaller wiring and lower voltage losses. Both of those "advantages" (to me they are) are very dependent on your installation. If you can't fit the larger modules, or expect them to be unevenly shaded, then it becomes much harder to justify the MPPT controller. If you have the space, an extra panel will usually get you more output gain than the MPPT controller.
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Old 21-03-2013, 18:03   #8
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Re: MPPT vs PWM Solar Charger Controllers

If you get something like this MPPT 25 amp controller...

Solar Cell, Solar Panel, Solar PV, Solar Products, Charge Controllers, Solar Trackers

.... you'd have about $180.00 into it and a good controller, there are better and there are worst (we have one of these on one boat).

Or you could use a PWM controller...

Solar Cell, Solar Panel, Solar PV, Solar Products, Charge Controllers, Solar Trackers

... like in the link and be good for 20 amps at about 76.00. So you have $100 more into the MPPT. True the $100 in panels will get you more right now but the solar can get addicting and sooner or later if you are cruising you will probably get more if you want to add a fridge or other items.

When that happens you will have a better overall system in my view. $100 over say 5 years is what $20 a year. Are you really going to notice that if you are using the boat.

We have MPPT on both boats and would do the same all over again...



Macgregor 26S Outside Mods page 33



Endeavour 37 Electrical Mods Index

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Old 21-03-2013, 18:17   #9
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Re: MPPT vs PWM Solar Charger Controllers

I have invested a fair amount into larger panels so I've spent the extra money for the high end controller however if you have a couple of batteries that are 100 amp plus each and one 100 amp solar panel you don't even need a controller as you could wire it straight to the batteries. Thats what I did on my first boat and it worked fine. I had a simple switch that I could use to turn them off but I never needed it except when I was on shore power.
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Old 21-03-2013, 18:48   #10
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Re: MPPT vs PWM Solar Charger Controllers

I checked into Flexible solar panels, they seem like a good idea so far, you can sew them into your bimini or just velcro them down, which I heard is the beast way. They are very thin and can store under a matress, sounds good to me....
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