plh
Explorer
I use this same meter and agree with AndrewP
Recommendations for an 80 watt off road ready vehicle Solar Panel?
- Thread starter Rezarf <><
- Start date
I use this same meter and agree with AndrewP
4x4junkie
Explorer
PWM stands for "Pulse Width Modulated". A PWM controller operates by connecting your solar panel array directly to your battery for charging. As the battery's charge level rises, the controller begins to turn off or "pulse" the panel's connection to regulate the charge current going into the battery.
Because the controller makes a direct connection of the panel to your battery, the panel's voltage will be pulled down to that of what your battery is. This pulling down of the panel voltage does not result in a corresponding increase in panel current, resulting in a loss of panel efficiency.
Pros:
Cost
Simple circuit design
Cons:
Wastes some of the energy that is available
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MPPT is "Maximum Power Point Tracking". It samples the voltage and current points of a panel to find where it's power output in watts (volts × amps) is greatest, and will then charge your battery from those points (stepping the voltage down, and the current up as needed). Due to this ability to step up the current it's common to see 10%, even 25% more current going into your battery than what the panel's actual current ratings are (especially when outside temperatures are cold). An MPPT controller however doesn't operate quite as efficiently at very low power levels as a PWM one can, which makes it important to size the controller to your array as close as you can (IOW, use of a 60 amp-rated MPPT controller for a single 100W panel will likely negate the advantage MPPT offers whereas a 10-amp MPPT controller will work much more efficiently with the 5¾ or so amp output of a 100W panel (maybe this is where the confusion came from in the post made earlier?)
Pros:
Maximizes a panel's harvesting capability
Allows use of (often less costly) HV grid-tie panels
Can allow use of smaller gauge wiring between panel to controller (such as with series-wired panels or with grid-tie panels)
Cons:
Cost
Sizing the controller to the wattage of your panels is more critical (overbuying on the controller to accommodate a future panel upgrade may not always be the best idea)
More reading here:
https://en.wikipedia.org/wiki/Maximum_power_point_tracking
http://support.morningstarcorp.com/...WM-vs-TrakStar-MPPT-Whitepaper-March-2015.pdf
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IdaSHO
IDACAMPER
I fail to see how circuit design is any different between the two.
What are you referring to?
IMO the ONLY pro for a PWM is initial cost.
On the other hand, thats also the ONLY con for an MPPT.
Once you get beyond the initial cost, its all gravy, and the entire system operates more efficiently.
Plus, it opens up the possibilities for higher voltage panels, which traditionally are often cheaper than standard 12V panels.
What are you referring to?
IMO the ONLY pro for a PWM is initial cost.
On the other hand, thats also the ONLY con for an MPPT.
Once you get beyond the initial cost, its all gravy, and the entire system operates more efficiently.
Plus, it opens up the possibilities for higher voltage panels, which traditionally are often cheaper than standard 12V panels.
Titanpat57
Expedition Leader
This is a pretty good read...
http://www.solar-electric.com/mppt-solar-charge-controllers.html/
http://www.solar-electric.com/mppt-solar-charge-controllers.html/
4x4junkie
Explorer
Internal circuits within the controller (could potentially affect reliability and cost to repair a unit, as well as possible radiation of more RFI if you also have 2-way radios).
Connecting either one into your solar system is the same however, if that's what you thought I meant.
IdaSHO
IDACAMPER
Gotcha
Although with MPPT and higher voltage panels, the controllers are seeing much lower amperage for a given watt output.
One could argue that that could even extend the life of said controller.
And as far as cost to repair/replace, yet another reason why I jumped on the EcoWorthy MPPT band wagon.
It is roughly the same cost of a similar amperage PWM with all the benefits of a MPPT.
And 1/3 the cost of a similar MPPT.
I could easily justify buying another unit just to keep on hand if I was concerned about failure.
But Im not, so I dont. :ylsmoke:
Although with MPPT and higher voltage panels, the controllers are seeing much lower amperage for a given watt output.
One could argue that that could even extend the life of said controller.
And as far as cost to repair/replace, yet another reason why I jumped on the EcoWorthy MPPT band wagon.
It is roughly the same cost of a similar amperage PWM with all the benefits of a MPPT.
And 1/3 the cost of a similar MPPT.
I could easily justify buying another unit just to keep on hand if I was concerned about failure.
But Im not, so I dont. :ylsmoke:
I have been running this same MPPT controller (although the one I bought was not branded Eco-worthy and was only $80 back then) for the past 3 years with no issues. Yes it is a true MPPT controller, and it has several nice features. You can manually set all the charge voltages to be just right for your battery system (be it wet cell, gell cell, AGM etc) and it gives you a readout on the total amount of power consumed.
Titanpat57
Expedition Leader
plh
Explorer
IdaSHO
IDACAMPER
While that unit would work fine, I see no reason to limit yourself to 10 amps
The moment you consider a similar wattage second panel, you will need more controller.
Id go to 20A and not look back.
That said, while Im 100% happy with my 20A Ecoworthy unit, I wish they had a 24/12V unit with more capacity.
The next step up is a 40A unit that is only 24/24v.
Im sitting at 200watts with a typical max amperage production of 17- 18 Amps, and am hungry for more.
For long term dry camping with sub-optimal solar conditions, 200 watts is barely cutting it.
The moment you consider a similar wattage second panel, you will need more controller.
Id go to 20A and not look back.
That said, while Im 100% happy with my 20A Ecoworthy unit, I wish they had a 24/12V unit with more capacity.
The next step up is a 40A unit that is only 24/24v.
Im sitting at 200watts with a typical max amperage production of 17- 18 Amps, and am hungry for more.
For long term dry camping with sub-optimal solar conditions, 200 watts is barely cutting it.
4x4junkie
Explorer
Well again, MPPT controllers don't work as efficiently if the panel's rating isn't a significant amount of the controller's rating (think of it like a 7000 watt generator powering a 1200 watt air conditioner vs a 2500 watt generator powering the same air conditioner. The 2500 watt gen will use much less gas to power the air conditioner).
If a planned panel upgrade is also in the near future, then of course that would be different.
However you also can parallel multiple controllers on the battery too... So should you run out of capacity on your first controller, you can always buy a second one (each controller must have it's own separate solar panel however).
If a planned panel upgrade is also in the near future, then of course that would be different.
However you also can parallel multiple controllers on the battery too... So should you run out of capacity on your first controller, you can always buy a second one (each controller must have it's own separate solar panel however).