Solar Panel-do I need a charge controller?

[TNLI]

As the original question is 10 years old, solar panels and batteries have advanced in technology and wiring protocols, e.g. diodes are almost always fitted in solar panels.

I am not sure about TNLI's fuse "between" each battery, , and an explanation would be useful.

Policies about connecting panels in series have been frequently discussed in the forums, and there are times when it is advantageous.


I think TNLI has an empirical approach to panels and charging regimes which may not reflect current best practice.

If for some reason you wire or connect batteries in parallel, the reason for putting a fuse is simple, if one battery fails it will cause the other to discharge, possibly fairly quickly. With a correctly rated solar panel feed fuse, the fuse might blow and even if does not, it will buy you time to notice that you have a battery problem.

The Fastnet yacht race disaster report stated that at least one yacht was abandoned cos some twerp selected the batteries to both, and that resulted in the engine not starting and an electrically dead boat. No one likes being on board a dead boat in a serious storm and they have a nasty habit of prematurely abandoning ship. Then they find out why toroidal life rafts were developed.

 

[TNLI]

Your 2 domestic batteries are wired in parallel.

All of your solar panels are wired in parallel too.

Wiring solar panels in parallel is sometimes necessary, although all of mine are in direct to battery or selector. Wiring batteries in parallel is a mistake, just buy a bigger sealed battery.

 

[PaulRainbow]

Wiring solar panels in parallel is sometimes necessary, although all of mine are in direct to battery or selector. Wiring batteries in parallel is a mistake, just buy a bigger sealed battery.

Sorry, but you're not making any sense.

Your two engine batteries are in parallel, so both of your panels that connect to them are also in parallel. Doesn't matter that you connect the panels direct or though a controller and it makes no difference that you connect a panel to each battery. The fact that the batteries are in parallel makes them effectively one battery. If you have a panel connected to each battery, that's parallel, but it's the wrong way to wire them. You should be taking the negative from one battery and the positive from the other to get better balance and the solar panels should both be connected to the same terminals.

Exactly the same goes for your two domestic batteries.

As for "Wiring batteries in parallel is a mistake, just buy a bigger sealed battery." that's just pure nonsense. Why haven't you just fitted bigger batteries ? There is nothing whatsoever wrong with connecting batteries in parallel. If one should fail, you can still use the others.

I recently fitted a pair of 230ah batteries on a yacht that weighed 55kg each, a single battery would therefore weigh 110kg, that'll be a bundle of laughs to carry down the companionway steps and lift under the sofa.

 

[TNLI]

Sorry, but you're not making any sense.

Your two engine batteries are in parallel, so both of your panels that connect to them are also in parallel. Doesn't matter that you connect the panels direct or though a controller and it makes no difference that you connect a panel to each battery. The fact that the batteries are in parallel makes them effectively one battery. If you have a panel connected to each battery, that's parallel, but it's the wrong way to wire them. You should be taking the negative from one battery and the positive from the other to get better balance and the solar panels should both be connected to the same terminals.

Exactly the same goes for your two domestic batteries.

As for "Wiring batteries in parallel is a mistake, just buy a bigger sealed battery." that's just pure nonsense. Why haven't you just fitted bigger batteries ? There is nothing whatsoever wrong with connecting batteries in parallel. If one should fail, you can still use the others.

I recently fitted a pair of 230ah batteries on a yacht that weighed 55kg each, a single battery would therefore weigh 110kg, that'll be a bundle of laughs to carry down the companionway steps and lift under the sofa.

THEY SURE AS HECK ARE NOT!

BAT 1 (600A start battery) fed to Engine only battery selector.
BAT 2 same as above.
BAT 3 (120Ah a thin plated deep cycle only sealed job) fed to House only selector.
BAT 4 same as above.
Note there are 2 sets of common negative feed cables and an emergency cross feed with a removable key.

 

[VicS]

Wiring solar panels in parallel is sometimes necessary, although all of mine are in direct to battery or selector. Wiring batteries in parallel is a mistake, just buy a bigger sealed battery.

The weight of a single large battery compared with the weights of two smaller batteries make a single large battery a mistake ,

 

[PaulRainbow]

THEY SURE AS HECK ARE NOT!

BAT 1 (600A start battery) fed to Engine only battery selector.
BAT 2 same as above.
BAT 3 (120Ah a thin plated deep cycle only sealed job) fed to House only selector.
BAT 4 same as above.
Note there are 2 sets of common negative feed cables and an emergency cross feed with a removable key.

If not parallel, how are they wired ?

 

[pvb]

The Fastnet yacht race disaster report stated that at least one yacht was abandoned cos some twerp selected the batteries to both, and that resulted in the engine not starting and an electrically dead boat.

That's just the result of having a wretched 1-2-Both switch! Nothing to do with wiring or fusing batteries.

 

[V1701]

I love it, a 10 year old thread, nobody actually wants to know anything or have a question answered and things are starting to get contentious. You gotta love the forum...

 

[Lacey.Sail]

I love it, a 10 year old thread, nobody actually wants to know anything or have a question answered and things are starting to get contentious. You gotta love the forum...