Current Strategies in Solar Power ?

[Roy M]

Bash: check this out: Trans Marine Pro - Marine Wind Generator D400. They have a combo 12 volt dc 300w/120 volt AC 500w for about $100. Scroll down to the bottom of the page for photo, etc.

[barnakiel]

AND

The expensive and good controller (MPPT) at 300 USD or so is said to put 20% extra on top of the deal. So, @300 USD I can buy maybe 50Watts of solar, times 5 (29%) ... makes 250 Watts.

meaning - untill my panels are in excess of 200 Watts, it is cheaper to buy more solar panels than go for the advanced regulator !

Just thinkin' aloud.

barnie

[cfarrar]

Roy,

I'm not an expert, but I can offer some real-world data. We use a Blue Sky 2512iX with 216 watts of Kyocera panels (1x130, 2x43). The panels are mounted above the bimini, with space underneath for airflow. Ours are wired in parallel so that shading doesn't effect the entire circuit. We ran 12-gauge wire from the panels, through the water-tight through-deck fitting, to a set of terminal posts. Then #4 cable to another set of terminal posts adjacent to the Blue Sky unit, mounted inside the nav station. Then #12 into the Blue Sky unit itself.

Within a couple of hours after sunrise we see 12.5 amps of charge from the Blue Sky unit. This is the panels' rated power, meaning that the MMPT controller is stepping the voltage down from roughly 17.5 to 13.5 with minimal loss of current. We often see 13.0 amps on a cool day. This appears to confirms Cal40John's point that parallel wiring is adequate for most 12V systems, and you don't need to wire in series to realize the benefits of MMPT.

By the way, we use the Blue Sky remote display, mounted next to the Link 1000 at the nav station. By comparing the two displays you can instantly assess the solar charger output (on the Blue Sky remote display), net battery charge (on the Link 1000 - actually this is simply current flow across the battery bus), and electrical system consumption (the difference between the two).

Hope that helps!