Jon,

You are technically correct but both are equal if you are reaching a full charge because both systems taper off to a float voltage at full charge.

Also MPPT only justifies it's higher cost if you never fully charge your batteries and your solar panels can produce a voltage significantly higher than your battery voltage, for example if your batteries are 12V and your wired-in-series solar panels are 36 volts. This will almost never be the case with a Vanagon 12V system.

Thanks, Tom Hargrave
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-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf Of Jon VO
Sent: Friday, May 29, 2015 8:39 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Re: Solar panel question

John,
The different panels will have a somewhat different I to V curve, and thus the maximum power point for each may be a bit different. Depending on the MPPT controller, this may mean a reduction in power transfer efficiency, but should still charge the battery. Some MPPT controllers generate a particular I to V curve for the attached panels, by sampling over time and various light conditions. Still better than a straight PWM approach.
Jon

On 5/28/2015 8:08 PM, J B wrote:
> The initial test run seemed to work great and pulled in over 10amps 
> during peak sunshine
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