Multiple solar panels to a common bus bar?

[Hoohaa]

Ten years ago I set up 2 panel's on my davits and on the advice of the guy that supplied the panel's, I installed 2 completely separate mppt controllers to isolate the panel's from each other inorder to minimise the effects of shadowing.
Apart from doubling up on wiring, it's worked fine.
I've since rewired the boat and upgraded the battery system, got rid of the second mppt controller and simply ran both panels to a small busbar mounted under the panel's and then onto a larger single mppt controller.
I can't see any disadvantages in doing it this way. Less wiring and very simple to add additional panels if require and it effectively isolates each panel from the effects of one of the panel's coping some shadowing.
Can anyone explain to me what the disadvantages are of doing it this way?

[mlydon]

None, really. Folks have experimented with series vs parallel, found parallel was better at keeping up charge when a panel has some shade. If a panel drops due to shade, the other should still be putting out amps,whereas with parallel, you get a voltage drop.

Matt

[ozsailer]

Gday hooha. Nothing wrong at all with whT you have done. The shadi g effect is a genuine concern but a very large majority of boats do not have this issue if designed correctly. There is also an argument for ensuring you have identical solar panels on each string of connections but if planned and wired correctly this can be overcome as well. The issue I see is ensuring that your controller is of sufficient size to take the load and that you have isolation/circuit protection on the solar panel side and also after the mppr controller. .

[Hoohaa]

Originally Posted by ozsailer

Gday hooha. Nothing wrong at all with whT you have done. The shadi g effect is a genuine concern but a very large majority of boats do not have this issue if designed correctly. There is also an argument for ensuring you have identical solar panels on each string of connections but if planned and wired correctly this can be overcome as well. The issue I see is ensuring that your controller is of sufficient size to take the load and that you have isolation/circuit protection on the solar panel side and also after the mppr controller. .

Thanks for the replies guys.
Oz so you're saying I should fuse the wire between the solar panel and the MPPT controller.

[Uncle Bob]

Originally Posted by Hoohaa

Thanks for the replies guys.
Oz so you're saying I should fuse the wire between the solar panel and the MPPT controller.

Personally I prefer to follow the advice of the equipment manufacturer. rather than some random internet poster.

[Hoohaa]

Hi Bob
Unfortunately I don't speak Chinese. So can't rely on the manufacturer.
As you know I DIY just about everything and appreciate whatever advice I can get including yours.
I recently upgraded all of my battery systems including researching and installing ANL fuses and busbars ect.
I've cut the plugs off my solar panels and hooked them up to a local bus bar. That particular cable is one of the few that I haven't fused.
At the end of the day it always comes down to myself researching and evaluating advice wherever I can get it.
To be perfectly honest, I just don't always trust what the retailers tell me, because that's who you usually wind up talking too.

[ejs]

What you did will work fine, you lose a small bit of efficiency if the panels aren't perfectly matched because wired in parallel, the output voltage of the two will only get up to the voltage of the weaker panel. Thi difference is usually a small percentage if the panels are from the same lot and manufacturer.
E

[Uncle Bob]

Jeff, I can sympathize, chinglish can make life difficult which is part of the reason that for major components I now only buy known brand name products. Have had problems in the past and decided just not worth the hassle. Having two controllers I found that the instructions indicated that after installation of the controller it was to be connected to the battery first via a fuse within 7 inches of the battery then the panels, no mention of fusing between controller and panels.

[Wotname]

Originally Posted by Hoohaa

Thanks for the replies guys.
Oz so you're saying I should fuse the wire between the solar panel and the MPPT controller.

There is no need for circuit protection between the solar panel and the controller providing the wire is sized to accommodate the maximum (short circuit) current of the soar panel. Almost always on most installations, the wire gauge is large enough to safely carry the full short circuit solar panel output current, thus no circuit protection is required.

You might want to provide isolation (i.e. a switch in this circuit) but again, there is no need to do so. The solar panel(s) can be easily turned OFF by shading them or waiting for nightfall.

There should be a fuse / circuit breaker located near the battery end of the wiring between the controller and the battery (charge bus or whatever).

[ozsailer]

Originally Posted by Uncle Bob

Personally I prefer to follow the advice of the equipment manufacturer. rather than some random internet poster.

Uncle Bob you raise a very good point and I should have stated that I am a qualified electrician and have installed several boat systems (for friends) I am retired now so do not get involved professionally any more. In regard to fusing the between the solar panels and MPPT I found that while it is not mandantory best practice was to put a Circuit breaker/switch between and then a high capacity circuit breaker after the solar MPPT controller. On a house here where I live an isolation switch is legally required at the solar panels so that they can be isolated when working on them from the house, Same on a boat. On boats I use a double pole circuit break as the isolation switch and then a high capacity CB after the MPPT controller. As a side note I have seen many a solar installation where the cabling is way undersized. Remember when working out voltage drop on boats with 12 volt systems you have to take into account the total distance IE length of active and neutral wires in determing this.,


Ozsailer

[NYSail]

I put a breaker just before the controller. Protection plus gives me an easy way to turn the juice off of I have a need to touch things.

My system btw has two panels in parallel going to a single controller. I have typically no issue with shading as panels are up on an arch above my bimini.

Good luck.

[Wotname]

Originally Posted by NYSail

I put a breaker just before the controller. Protection plus gives me an easy way to turn the juice off of I have a need to touch things.

My system btw has two panels in parallel going to a single controller. I have typically no issue with shading as panels are up on an arch above my bimini.

Good luck.

If you put a circuit breaker (or fuse) between the solar panel and controller, it should be located as near as practicable to the solar panel.

A circuit breaker (or fuse) should always be used between a controller and the battery and located near the battery. Depending on the controller, another circuit breaker (or fuse) may be required near the controller although better controllers have built in short circuit protection.

[smac999]

Originally Posted by Hoohaa

it effectively isolates each panel from the effects of one of the panel's coping some shadowing

How does connecting all the panels to the same bus bar isolate them?…. .

If some panels are getting shaded. You would be better off having each panel go to it’s own controller. The way you had it.

[Uncle Bob]

So far we are better off than a previous thread on a similar topic (not sure when) where an "expert" chimed and expressed the opinion that all installs should have a fuse at the battery, a fuse on the battery side of the controller, a circuit breaker on the panel side of the controller and a fuse at each panel.

[ozsailer]

Originally Posted by Uncle Bob

So far we are better off than a previous thread on a similar topic (not sure when) where an "expert" chimed and expressed the opinion that all installs should have a fuse at the battery, a fuse on the battery side of the controller, a circuit breaker on the panel side of the controller and a fuse at each panel.

Uncle Bob. I will make one last comment, The vast majority of electrical installations I saw on boats undertaken by those without the requisite skills left a lot to be desired and if the same standard was undertaken on a domestic house would be condemned. If in doubt, employ a appropriately qualified person to undertake the work. I recently watched a few youtubers who undertook their own electrical modifications and who were quite clearly not qualified to undertake the work. Some were so dangerous in what they were doing and saying it was actually life threatening. Unfortunately as you allude to, there are many who are prepared to make recommendations without the requisite skills to make such comment.

Ozsailer