Solar Regulator On/Off Switch?

[Tim Good]

When I got my boat it had a single 120w panel via a good quality PWM controller. The previous owner installed an On/Off switch to literally cut the power to he batteries. He said this was to prevent the solar panels overcharging the batteries when either the engine or shore power was charging.

Is there any merit / trust behind this?

I ask as I'm not adding 240w and putting them in series via a victory MPPT controller. Should I wire a switch into the wires to cut off the charge to the batterIes as before or is it not required?

Note: the wiring is such that I can divert solar charging to my main domestic bank, engine battery, bow thruster battery or all all together as one via a big "1, 2, both or all" battery switch.

 

[RichardS]

It's a waste of time. A good controller, as you have, will sense that the batteries are fully charged, whatever source they are being charged from, and will either stop charging or drop into float mode depending upon its design.

Richard

 

[duncan99210]

The main point of a regulator in a solar charging system is to prevent overcharging. The regulator senses the battery voltage and ensures that once the bank is fully charged it only supplies a float charge to the batteries. The various flavours of regulator all seek to maximise the energy flow to the batteries up to that point (ie fully charged) and then simply supply enough voltage to maintain a full charge. So no need for a switch between panel and batteries. However, nothing wrong if you want to build one in.

 

[travlinon]

On the assumption that the on/off switch you mention is cutting the power to the controller and thus the batteries, is a good idea if your other switch ie. 1, 2, both and all also has a off switch. The reason being Is that all controllers that I have installed require the battery to be connected first ( so that the controller can recognise the voltage of the battery ie.12 or 24 volts, then the solar panels are connected - strictly in that order. If you use the off part in the 1,2,both, off switch then the battery has been disconnected from the controller and to reconnect you should then turn off the panel- controller switch before selecting the 1,2, both, all switch. I have this setup as it is makes it easier for me to fully disconnect the batteries from the controller for testing or working on the batteries.
Ignore the above if your switch that you talk about isn't between the panels and the controller or your controller doesn't require the "battery first - solar panels second connection.
Check the maximum input of your controller before connecting the additional panels.

 

[NormanS]

Can anyone explain to an electrical numpty where the power from a solar panel goes when the regulator decides that the batteries are fully charged. Surely the panel is still trying to produce power. I speak as one who has just recently installed a 100W unit, which is controlled by my HRDi controller, which also copes with my Rutland 913 wind genny.

Incidentally, I'm just back from a fortnight's cruise on the West Coast in fairly average weather for the time of year, when the wind genny, and the PV panel produced exactly the same number of amp hours. The PV panel cost £77, so based purely on capital cost, the solar power was about one tenth of the cost of the windmill power. Impressed!

 

[VicS]

Can anyone explain to an electrical numpty where the power from a solar panel goes when the regulator decides that the batteries are fully charged. Surely the panel is still trying to produce power. I speak as one who has just recently installed a 100W unit, which is controlled by my HRDi controller, which also copes with my Rutland 913 wind genny.

Nowhere just like it goes nowhere when you switch a torch off!

 

[RichardS]

Can anyone explain to an electrical numpty where the power from a solar panel goes when the regulator decides that the batteries are fully charged. Surely the panel is still trying to produce power. I speak as one who has just recently installed a 100W unit, which is controlled by my HRDi controller, which also copes with my Rutland 913 wind genny.

Incidentally, I'm just back from a fortnight's cruise on the West Coast in fairly average weather for the time of year, when the wind genny, and the PV panel produced exactly the same number of amp hours. The PV panel cost £77, so based purely on capital cost, the solar power was about one tenth of the cost of the windmill power. Impressed!

Look at it this way - when you put a panel out in the sun with the cable not connected to anything, where does the power go?

Richard

 

[rogerthebodger]

Look at it this way - when you put a panel out in the sun with the cable not connected to anything, where does the power go?

Richard

It come out of the ends of the wires and all over the floor. All these little electronics getting under your feet.

Couldn't resist that.

 

[VicS]

It come out of the ends of the wires and all over the floor. All these little electronics getting under your feet.

Couldn't resist that.

but for mains electricity you can get these blanking caps that fit into unused sockets to stop the electricity leaking out

 

[rogerthebodger]

but for mains electricity you can get these blanking caps that fit into unused sockets to stop the electricity leaking out

That's good to know Vic but the ones you show wont fit our plugs as ours have round pins.

 

[NormanS]

Look at it this way - when you put a panel out in the sun with the cable not connected to anything, where does the power go?

Richard

That was why I asked the question. With my wind genny, when the batteries are fully charged, the power is used to slow down the turbine. Heat is generated, and eventually the turbine goes into hyperdrive until it cools down, when the cycle is repeated.

 

[Happydaze]

I fitted a switch to turn the solar panels off when i have the engine running, not to stop the batteries overcharging but to get the batteries charged. I have found this makes a fair bit of difference so I guess without it the voltage from the panels tell the alternator regulator that the batteries are full and the alternator voltage tells the solar regulator the same so only a few amps flow.