Victron Solar

Solar Upgrade

Based on the conversations detailed in the earlier post (below) I decided to remove the wind generator, which was obviously shading the solar panels.      This and a good cleaning saw the 2X100w solar panels produce much closer to their nominal 200w.    Regardless, I have decided to upgrade the solar panels to a nominal 400W.  This will help offset the loss of the wind generator, and should, in sunny regions be more than enough to keep the batteries charged.   (I duly note that most cruisers opt for more than this)   

I was concerned that I could not find a form factor that would not exceed the width of the arch.    Fortunately,  Renogy offers a size that fits in a 200w 24v panel.  A pair of these should fit comfortably within in the existing width, while extending only 8.5" further fore/aft.       (49.7"X 30" vs 47X21.5")     https://www.renogy.com/renogy-16bb-n-type-200-watt-24v-solar-panel/

Each 24V 200w panel  will produce around 5 amps at 37V, and obviously the pair will produce double that.   The existing Smartsolar 100/30  MPPT controller is therefore just adequate for the pair.   (100V is max input voltage, and 30A is max output current.  400w  at 14.6V=27.4a.)  A higher output or second MPPT controller should probably be used, so I purchased a Victron Smartsolar 100/50 for this purpose.   This provides redundancy plus a variety of wiring options, including series wiring, two controllers etc.   

The obvious advantage to any higher voltavge/lower current PV installation is that the Victon MPPT controller does not operate until the solar panels produce 5V more than the set battery voltage. (14.6VDC in m case).  This means that with 12V panels, in lower light conditions the MPPT might not be producing at all

  has a floor voltage meaning, 

While I do not wish to install any more fixed panel area at this point, the existing panels could be used at anchor if I cared to fabricate some sort of removable bracket.  

Original post.

Sakura came equipped with 2X100w parallel-wired Victron SPM100-12/3a solar panels and a Victron 100/30 MPPT controller, charging an aged 4X100AH AGM house bank. (since scrapped and replaced with 2X230AH Lithium)  These panels have kept the house bank charged while the boat has been on the hard and during my periodic refit visits over the past year.   

As discussed below, these panels are producing less than 100w under ideal solar conditions.   Each is producing a similar 40w individually.   What is obviously not ideal is the presence of the wind generator directly above the panels. It appears that the wind generator installation may have preceeded the panel installation, resulting in shaded panels.  

Reimagining the use of the arch, and updating the bits mounted thereto is a project in itself. 

The MPPT controller will be moved to the electrical area under the port side aft berth.  The solar panel wiring will be brought to that location also so that series/parallel can be wired there.  
 

In May 2024, I finally decided to download the Victron app and see (via bluetooth from the MPPT controller) what the panels were doing, and was surprised to find that the two were typically generating a total of less than 100W total.  50-85w typically, at 16-18VDC.    This at mid-day, in the tropics.   When connected individually, both panels behaved similarly, with each generating 25-40W.  

Based on my experience with a 175watt installation on Windstar, which generated much more electricity,  I find it hard to believe that the panels are functioning as they should. 

I havent yet had a chance to methodically examine this, but I did post online, asking the following:.  

• Is this normal with these panels?  
• Are the panels failing? (identically?)
• Could tired batteries be the cause?
• Could there be an issue with the MPPT controller?
• Could the controller have been programmed in such a way as to cause this?

Responses were:

• Panel is shaded, mostly by the wind generator.  This will significantly reduce output.
• Connections should be checked for corrosion.
• MPPT controller may be more efficient if panels are connected in series.
• A seperate controller for each panel is ideal.
• Bifacial or better quality panels (CIGS) would help.
• panels will rarely be at 90deg to the sun, significantly reducing efficiency.

So, the strategy might be to:

1. clean up the connections 
2. remove the wind generator 
3. re-wire panels in series.   (and compare)
4. measure output with each change. 

Panel dimensions are 47X21.5", frame is 1.375"h

mounting frames are 23 3/16" o/c