Shaded Panels - Catamaran Boom

[HeywoodJ]

Originally Posted by sv Stella Maris

**This is tested, not opinion:

We had (7) panels on our cat, total of 2,320 watts. Experimented with multiple configs. Takeaway:

-new split cell panel technology (such as Q-Cell panels) completely eliminated the concern for shading. Even in series with a middle panel completely shaded the other panels are not affected at all.

With split cell tech this debate is a mute point of the past....

And this is why I generally don't participate in these threads. CatNewBee is too nice (and that is the rule here on CF). Split cells, PERC, none of that changes the basics of shading. Split cells just means there are more "cells" on a module, which may or may not help with shading. PERC (Q-cells) is old technology that is supposed to reflect sunlight into the back of the cell. The entire industry has moved away from PERC and toward bifacial because PERC didn't create that much in gain.

Since you say it "is tested" show us the test results. Show us where you covered a single cell with an opaque material and the whole rest of that module kept producing at full power. Quite frankly, if any module maker could demonstrate that the whole industry would be marching to their door.

There' nothing moot about shading, it is still the biggest headache in the industry. Just a single overhead cable casting a hard shadow can destroy output in 2021 (and it will in 2022 too).

[skenn_ie]

Originally Posted by hzcruiser

Can you prove or corroborate such an outlandish statement please?

https://blog.spiritenergy.co.uk/cont...ading-analysis


I await your apology !

[skenn_ie]

Originally Posted by hzcruiser

You mean protective earth, not AC neutral, I take it?

Protective Earth should be connected to AC neutral SOMEWHERE. Just make sure that you have galvanic isolation before plugging into shore power !

[skenn_ie]

Originally Posted by Pete7

A lot of yachts in Europe have the AC earth connected to the DC negative and on to an anode, mine does. What we don't generally have is seacocks wired to the DC negative, but that's another story.

Pete

Connecting through-hull metalwork together creates a battery unless they are (unlikely) identical metals. In timber hulls, that will damage the wood around the fittings too (turns black and disintegrates). I have read one recommendation that, for timber boats, there should be no earth-bonding, and propshaft should have a cast-iron anode. Zinc is too galvanically active.
This was after careful experiment and scientific analysis.

[Wolfgang.Schau]

Originally Posted by ArranP

Following are two layouts for solar panels, I have attempted to demonstrate the shading when the boom is on the left and when the boom is on the right side.

I am uncertain of the best possible configuration in terms of strings and parallel.

I have 4 mppt charge controllers, more can be add more if need be. Panels are 500w 1.2m x 2.1m

Attachment 249722

Attachment 249723

Thank you for your comments

Panels on the roof under the boom are a bad idea. How do you walk along the boom when you tuck the sails in your sail bags?
You should not walk on the panels, you will break the glass. Only special flexible panels may allow walking on them.
I have my panels (3 x 275W) on top of the davits, no shading, no problems, I never ran out of power.

[daydreamer]

Most cruisers spend most of their time at anchor. Where do you keep your boom when you're not sailing?

Will you be cruisng in the Bahamas or the Caribbean? The wind there is almost always from the east. Solar panels on the port side are much less effective. If I were redoing my boat, I would set up for a starboard side bias -- more panels, permanent tilt, offset from boom, etc.

[Pete7]

Originally Posted by hzcruiser

You mean protective earth, not AC neutral, I take it?

Yes, we don't tend to use the word "neutral" rather positive, negative and earth.

Pete

[nilespf]

Quote:
Originally Posted by sv Stella Maris
**This is tested, not opinion:

We had (7) panels on our cat, total of 2,320 watts. Experimented with multiple configs. Takeaway:

-new split cell panel technology (such as Q-Cell panels) completely eliminated the concern for shading. Even in series with a middle panel completely shaded the other panels are not affected at all.

With split cell tech this debate is a mute point of the past....





Read the links, when you fully understand how PV's are designed and configured you will know that by definition, current production solar panels cannot and never will (using today's designs ) recover from a hard shadow. Bypass diodes are a consequence of keeping the panel from burning if a hot spot were to develop. Bypass diodes allow the panel to remain useful (only if the shading is limited) but always will protect your system from hot spots. Proper series/parallel combinations may allow the panels to function in spite of shading but if you do not "design" the panels in then your just guessing/hoping.

[ArranP]

I have confirmed with my local surveyor that, there is no upper limit for DC voltage coming from a PV array set in the criteria that would prevent one getting insurance on their boat.