Wiring solar panels to 1/2 switch, instead of battery

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gregcope

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Hi all

I am considering wiring another solar regulartor to the 1/2 battery master switch and negative bus bar.

This saves allot of wiring hassle, as well as increasing the effective wire diameter to reduce voltage drop. I am going to fuse the wiring so that it is possible to disconnect. Present wiring runs through conduits (between outer and inner hull; void is foam filled), and there is little spare room. The batteries are around 6M (wiring length) from the switches/regulators.

Anything I should consider?
 
Of my 8 solar panels 6 are wired through my 1/2 battery switch and the other 2 are wires direct and to to the separate batteries.

The ensures the batteries are just kept topped up when not on board but have full input when we are using all the electrical equipment on board.

All through separate regulators. A bit OTT may be but it works for me.
 
Rogershaw said:
Of my 8 solar panels 6 are wired through my 1/2 battery switch and the other 2 are wires direct and to to the separate batteries.

The ensures the batteries are just kept topped up when not on board but have full input when we are using all the electrical equipment on board.
Click to expand...

Sounds like you have some of your regulators on the switched side of the switch. I was proposing to just use the switch posts and connect up the regulators to the batteries (via a fuse). I the 1/2 switch would not do anything. These would always be on.

For context I have 100W of panels (2x50W) on the deck. I have a 100W roving panel (only used when "stopped"). I might add another "rover".

Rogershaw said:
All through separate regulators. A bit OTT may be but it works for me.
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I have the same. Both 50Ws have their own, as does the present rover. If I add another rover, it will share the existing rovers regulator. This reduces connection complexity (where I seem to have had issues), although increases wiring a bit. The biggest upside is redundancy. I have had connections issues, these sometimes take all panels out, which is annoying, so simple redundancy is good IMHO. KISS.
 
No reason not to, but you would be right to connect them to the battery input to the switch. It's not a good idea to "turn them off".
 
I haven't fitted solar to Seminole yet but I was under the impression that I had to use one controller for multiple panels.

I thought that input A would see the battery voltage and charge accordingly.

The controller for input B would see the voltage from input A and think, battery is full, no need to do anything.

Do they control on something other than battery voltage?
 
aquaplane said:
I haven't fitted solar to Seminole yet but I was under the impression that I had to use one controller for multiple panels.

I thought that input A would see the battery voltage and charge accordingly.

The controller for input B would see the voltage from input A and think, battery is full, no need to do anything.

Do they control on something other than battery voltage?
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If you have separate regulators there's going to be a voltage drop anyway between the ouput of regulator A and the battery, so regulator B won't 'see' the voltage at output A. (That assumes battery capacity is much bigger than the solar output - might be different if you were using 2,000W of panel to charge a motor cycle battery, but I'm presuming you aren't thinking of that).
 
I think people get a bit over concerned about volt drop in cables for solar controller to battery. It is not like say mast head light where volt drop means less volts so less current both drops meaning less power.
In a battery charging situation any volt drop from high current means less current into the battery so less volt drop so kind of auto limiting losses. It is unlikely you will be trying to pump so much current into the battery anyway. Mostly limited by solar power but also by battery charge state.
Re the original question. By all means use the terminals a the back of the 1,2,both switch to access battery pos connections. However if you go to the common terminal then for charging both batteries you must leave 1,2,both switch on both when boat is unattended. Sort of negates the purpose of the isolation switch.
Best option then with multiple panels is to have 2 controllers fed straight to battery via fuses. Then you can turn all power off when leaving boat. You can still go to "both" for all -panels to the weakest battery. olewill
 
It's not generally necessary to charge the Start battery from solar as that is quickly re-charged after every start unless the battery is weak so I would connect to the incoming terminal for 'house' battery only.
 
ghostlymoron said:
It's not generally necessary to charge the Start battery from solar as that is quickly re-charged after every start unless the battery is weak so I would connect to the incoming terminal for 'house' battery only.
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I agree the engine battery needs minimal charging, if any. I have two solar banks, each of 60w, one was connected to each battery bank. Seemed a waste of half of my solar output keeping the engine battery topped up, so i wired them all to the domestic bank. The alternator goes to the engine battery and there is a dual sensing VSR between the two battery banks.
 
I struggled to decide how to wire my panel wrt the engine battery. I went the other way to Ghostly and Paul. I moor mid-river, so the main reason for my panel's existence is to make sure that if I don't go to the boat for a while, the batteries are topped up, and most importantly, the engine starts! Once started, I can charge anything. I went for a controller that has two separate battery outputs - so half of the solar isn't wasted - once the engine battery is topped up, it all goes to the house battery.

The downside is that there are no two-battery-bank mppt controllers - I had to go with pwm, but with only one 100w panel, in the UK, under the boom, I understand that the benefits of mppt wouldn't really be seen in my scenario anyway.
 
Does your system have an 'emergency start" facility? where you can select or parallel the start battery. If not you can use jump leads. This would allow you to use all the solar to charge the house battery.
You could also achieve it by using a dual sensing VSR.
Polly's Kettle said:
I struggled to decide how to wire my panel wrt the engine battery. I went the other way to Ghostly and Paul. I moor mid-river, so the main reason for my panel's existence is to make sure that if I don't go to the boat for a while, the batteries are topped up, and most importantly, the engine starts! Once started, I can charge anything. I went for a controller that has two separate battery outputs - so half of the solar isn't wasted - once the engine battery is topped up, it all goes to the house battery.

The downside is that there are no two-battery-bank mppt controllers - I had to go with pwm, but with only one 100w panel, in the UK, under the boom, I understand that the benefits of mppt wouldn't really be seen in my scenario anyway.
Click to expand...
 
ghostlymoron said:
Does your system have an 'emergency start" facility? where you can select or parallel the start battery. If not you can use jump leads. This would allow you to use all the solar to charge the house battery.
You could also achieve it by using a dual sensing VSR.
Click to expand...

My solar does charge the house battery - that's the point of the controller being able to do two battery banks. I've probably been overcautious by connecting to the engine battery, but I have this fear of being unable to start. However if the engine battery actually failed, the two battery banks are in different parts of the boat, so I would be in trouble - I'd need long jumps to get from one to the other, and I confess I haven't set up to solve that problem. It's unlikely though (I hope!) - the wiring is such that it isn't possible to choose to use the engine battery for the house, so it should never be deep discharged, so we are really talk about a manufacturing fault or battery end of life.
 
Polly's Kettle said:
The downside is that there are no two-battery-bank mppt controllers - I had to go with pwm, but with only one 100w panel, in the UK, under the boom, I understand that the benefits of mppt wouldn't really be seen in my scenario anyway.
Click to expand...

I did some testing when i first installed the MPPT controller and only had it connected to the 2x30w panels on the coachroof. The effect of the shading on the panels was shocking. The 60w panel at the pushpit doesn't get a shadow and works much better.
 
Rogershaw said:
Why 6 of my panels are connected to the switched side of my 1/2 switch without and problems.

A simple on/off regulator effectively turns the current from the panel off when the battery voltage reaches the set point.
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I somehow had it in my head that it wasn't a good idea to turn them off, seems that i was mistaken :redface-new:
 
Interesting to see how we all manage things differently.
1) I have the same concern as Bob - if you wire regulators in parallel I'm not sure that they would control properly - one might always be favoured at the cost of reduced current output from the other - I don't have an answer to this, maybe Victron or someone does.
2) Regulators should be as close to the battery they feed as possible so there's no loss between reg and battery.
3) Why has no-one thought of trickle charging starter battery from domestics? A simple trickle charger can be made from a car light bulb and a Schottky diode, cost is light bulb plus about £1.
 
whiteoaks7 said:
3) Why has no-one thought of trickle charging starter battery from domestics? A simple trickle charger can be made from a car light bulb and a Schottky diode, cost is light bulb plus about £1.
Click to expand...

You have to be careful that you don't create a situation where the engine battery could discharge the domestic bank, especially if it developed a fault. My solution was to fit a dual sensing VSR, if either bank reaches a sufficient voltage, the relay closes and all batteries are charged. But, if one bank tried to too much from the other, the voltage would drop and the relay would open. I also have an emergency start switch, so if i have a faulty or flat engine battery i can start the engine from the domestics.
 
This is intriguing, so I'm going to put a 'design' question to those here who know their Biz.

....But on a separate thread.
 
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