Solbian Solar Panels

[SO49]

Thanks for the answers.

Just to make sure I understand how solar panels work - if you have three panels in series and one is shaded then the shaded panel blocks the output. What if the panel is only partially shaded the other in series panels are in full sun - what happens then?

What's happens if the same panels are in parallel - does the shaded panel get back fed from the other two panels in full sun?

Assuming all six panels are identical.

Thanks, Jeff

[noelex 77]

Originally Posted by SO49

Thanks for the answers.

Just to make sure I understand how solar panels work - if you have three panels in series and one is shaded then the shaded panel blocks the output. What if the panel is only partially shaded the other in series panels are in full sun - what happens then?

What's happens if the same panels are in parallel - does the shaded panel get back fed from the other two panels in full sun?

In parallel if one panel is completely shaded it will have zero (almost) impact on the output of the two panels in the sun.

In parallel if one panel is partially shaded the output will never be less than the normal output from the two panels in the sun, but there is likely to be little contribution from the partially shaded panel unless the shadowing is small or not very dense.

In series if one panel is completely shaded it will have an impact on the output of the two panels in the sun but their output will not be blocked completely. The exact output will depend on the number of blocking diodes and the location and density of the shadow.

In series if one panel is partially shaded the output may be less than the normal output from the two panels, but there is more chance that the panel in partial shadow will contribute something worthwhile. Thus the output could be higher or lower than the parallel connection.

It is very difficult to mathematically model parallel and series connection in conditions of varying shadows, which is so common in boat installations. The overall practical evidence favours parallel connection. This would be my recommendation unless it is impossible to install a suitable wire size for the higher current that will be delivered from the panels.

[Safari38LH]

Wow, great discussion. I am also putting 6 panels on my awning. They are Gioco 95 watt panels. I was going to put the port 3 in series and the starboard 3 in series. Can I then wire them in parallel to one controller or would it be better to wire each series to a separate controller.

[SO49]

Hi Safari:

I'm no expert but I suspect the issue might be finding a MPPT controller that could handle 600 watts. I've only been able to find 400 watts maximum.

Jeff

[smj]

Originally Posted by SO49

Hi Safari:

I'm no expert but I suspect the issue might be finding a MPPT controller that could handle 600 watts. I've only been able to find 400 watts maximum.

Jeff

There's a ton of MPPT controllers that can handle 600 watts. Theoretically your looking at a 50 amp input. Hers a couple that would have no problem. https://www.victronenergy.com/solar-...rs/mppt-150-70

[Paul L]

Originally Posted by Safari38LH

Wow, great discussion. I am also putting 6 panels on my awning. They are Gioco 95 watt panels. I was going to put the port 3 in series and the starboard 3 in series. Can I then wire them in parallel to one controller or would it be better to wire each series to a separate controller.

You can. the downside if you are using an MPPT controller it can not optimize both series differently, so a shadow on one will affect the optimization. Two controllers will also give you redundancy should one die.

[Safari38LH]

Originally Posted by SO49

Hi Safari:

I'm no expert but I suspect the issue might be finding a MPPT controller that could handle 600 watts. I've only been able to find 400 watts maximum.

Jeff

I believe the Blue Sky SB2512iX. Could handle it. When you do the numbers it's around 300watts, 35Volts, max 16 Amps.

[SO49]

I checked the link for Victron. Those controllers appear to be for home roof mounted solar panels. Do you think they'd work in a marine environment?

Jeff

[smj]

Originally Posted by SO49

I checked the link for Victron. Those controllers appear to be for home roof mounted solar panels. Do you think they'd work in a marine environment?

Jeff

http://www.bruceschwab.com/solar-pow...e-controllers/

[SO49]

I took some measurements of my bimini and the supporting bows. The aft section has zippers for the backstays to pass through the bimini. As a results I would need to use two of the smaller 43.7 x 21.3 inches solar panels on the aft sections while the front two sections of the bimini have enough flat area to support four 54.3 x 26.8 inch solar panels.

My question, then, is how to connect the smaller panels (probably 80 watts) with the larger (~ 125 watt) panels. I'm thinking I should put the three panels on each side of the bimini - two 125 watt and one 80 watt - in series and then either run each group into a separate controller or run the two groups in parallel into one larger controller. I know this setup was suggested earlier but that was before I figured out that I'd need two of the smaller panels.

Another possibility (and maybe easier to live with) is to connect the two panels on each side of a section of the bimini in parallel (recognizing one side of the bimini could be shaded) and then connect the sections in series.

[Scott Berg]

Each panel should ideally have its own MPPT controller
That optimizes the output per panel and the net cost isn't much more. Small Victron MPPT controllers are under $100 each and work very well.

[Paul L]

Originally Posted by Scott Berg

Each panel should ideally have its own MPPT controller
That optimizes the output per panel and the net cost isn't much more. Small Victron MPPT controllers are under $100 each and work very well.

Scott
He's talking 6 panels, so the individual controller per panel is pretty steep. Practically one for each group that is likely to shade the same should be fine. Say one controller for port side and one for starboard, assuming all panels have the same voltage specs.

[SO49]

I'm confused about whether I need to add a fiberglass back sheet under these solar panels or I can use them as is. I would think that after adding a fiberglass back sheet they wouldn't be very flexible.

I'm also confused about whether I want monocrystalline or polycristalline solar cells. Can they both be flexible?

Sorry, I think the more I read the more confused I am getting.

Jeff

[OrangeCrush]

Originally Posted by Paul L

You can. the downside if you are using an MPPT controller it can not optimize both series differently, so a shadow on one will affect the optimization. Two controllers will also give you redundancy should one die.

When I had multiple panels on one controller on my last boat, I was told I needed backflow diodes on each panel. They seemed to perform well even when one panel was shaded.


Sent from my iPhone using Cruisers Sailing Forum

[SO49]

Let's say I decide to order solar panels from Lensunsolar or another brand from China how do I figure out what the import taxes will be ? I did a little research and found that import taxes on Chinese solar panels can range from 20% to 240%

Jeff