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eid

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I recently upgraded my solar panels and regulator to 2x 260w panels and a Victron MTTP Smart 100/50. I have connected the panels in series and they are outputting at ~60v (so 30v each).

 

I am now wondering what would happen if I also connected one of my old panels either in series with these, or with the 2 new ones in series but the old connected in parallel. The old ones output 19v. Would the voltage received at the controller be lower than it is now in both cases (parallel and series)? Is this safe to do or am I likely to break something?

 

 

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35 minutes ago, WotEver said:

What are the specs of the 260W panels and the old panel?  
 

Parallel won’t work but series might. 

 

I have no idea what specs you mean apart from what I've already stated above. I have the manuals for the new ones but not the old. What information is important?

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59 minutes ago, eid said:

What information is important?

Max current specifically, because if the old one is lower than the new ones it will limit them.  As a general rule it's not great practise to combine different panels.

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The maximum current from the panels will be limited to the lowest rated output current of the three panels.  The new 260 watt ones sound as though they wiill have an output current of about 8 amps (exact figure on the label on the back) and The older one is hopefully a 100 watt panel with a max current of about 5 amps (if smaller the max current will be less). If so the max current you could get from 3 panels in series is 5 amps the bigger panels being throttled.

Your old panel, or panels had a controller, just keep it there, and put the new one in as well, then there is no conflict, one charger will go into float earlier than the other but while your batteries need charging both chargers will play their part.

 

You may find that putting the panels in parallel will be better because of partial shading, particularily so if they are on opposite sides of the boat and sloping slightly differently.

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1 minute ago, WotEver said:

Max current specifically, because if the old one is lower than the new ones it will limit them.  As a general rule it's not great practise to combine different panels.

I see. I'll probably leave it then. Thanks for the advice.

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1 minute ago, Detling said:

The maximum current from the panels will be limited to the lowest rated output current of the three panels.  The new 260 watt ones sound as though they wiill have an output current of about 8 amps (exact figure on the label on the back) and The older one is hopefully a 100 watt panel with a max current of about 5 amps (if smaller the max current will be less). If so the max current you could get from 3 panels in series is 5 amps the bigger panels being throttled.

Your old panel, or panels had a controller, just keep it there, and put the new one in as well, then there is no conflict, one charger will go into float earlier than the other but while your batteries need charging both chargers will play their part.

 

You may find that putting the panels in parallel will be better because of partial shading, particularily so if they are on opposite sides of the boat and sloping slightly differently.

^^^^ all of this :)

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6 minutes ago, Detling said:

The maximum current from the panels will be limited to the lowest rated output current of the three panels.  The new 260 watt ones sound as though they wiill have an output current of about 8 amps (exact figure on the label on the back) and The older one is hopefully a 100 watt panel with a max current of about 5 amps (if smaller the max current will be less). If so the max current you could get from 3 panels in series is 5 amps the bigger panels being throttled.

Your old panel, or panels had a controller, just keep it there, and put the new one in as well, then there is no conflict, one charger will go into float earlier than the other but while your batteries need charging both chargers will play their part.

 

You may find that putting the panels in parallel will be better because of partial shading, particularily so if they are on opposite sides of the boat and sloping slightly differently.

Thanks, that's very helpful.

 

The older one is ~5A I believe so it would restrict them. I can't use the old controller as it does a boost charge and my new batteries (lead carbon) don't like this. It's not a big deal, I was mainly just wondering how (or whether) this would all work together.

Edited by eid
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5 minutes ago, Chewbacka said:

You could use the old panel to keep the engine start battery topped up in winter,  ut you will need another controller for it.

I have been considering this.

 

What I have set up at the moment is a Victron battery charger connected only to the started battery. So I can top up the starter battery using power from the main bank, through an inverter. The good thing about this is I don't have to run more cables through the roof.

Edited by eid
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54 minutes ago, Detling said:

You may find that putting the panels in parallel will be better because of partial shading, particularily so if they are on opposite sides of the boat and sloping slightly differently.

Am I correct in thinking that having them in series lowers the loss of power through the cables? If not, what is it?

 

I do have an extra cable if I decide to go parallel.

 

The panels are probably going to be flat on the roof when I get the mounts.

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2 hours ago, eid said:

 

 

 I can't use the old controller as it does a boost charge and my new batteries (lead carbon) don't like this.

If it is programmable ie Tracer or Victron and probaby others just set the boost to 14.4 or whatever the battery max is. I have AGM so same problem but my tracer is set to charge max is 14.3 and boost is 14.4 and the boost time is 0.1 hours float is lower but can't remember it 13.sommat.

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2 hours ago, eid said:

I have been considering this.

 

What I have set up at the moment is a Victron battery charger connected only to the started battery. So I can top up the starter battery using power from the main bank, through an inverter. The good thing about this is I don't have to run more cables through the roof.

Not really a very good idea, and totally inefficient.

 

Generating 12 volts and putting it into 'storage' (with losses)

Taking it from 12v storage and inverting it to 230v AC (with 10% losses)

Taking the 230vAC and converting it back to 12v via the battery charger (with losses)

Putting the 12v into the starter battery (with losses)

 

If your starter battery is 'flat' and your domestic batteries are 'low' due to a day or twos usage whilst moored up, then you may not have enough power to start the engine.

 

Put a split charge relay (VSR) in the system and charge both the starter and domestic batteries from the Solar panels.

Many folk connect the VSR up so it charges the domestics first and then switches over to the starter battery - personally I prefer to charge the starter battery first and then switch over to the domestics, if the Sun isn't shining I'd rather what solar there is goes into the starter battery, if I can start the engine I can always run it to charge the domestics.

 

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1 hour ago, Detling said:

If it is programmable

 

Unfortunately not.

 

 

48 minutes ago, Alan de Enfield said:

Not really a very good idea, and totally inefficient.

 

Generating 12 volts and putting it into 'storage' (with losses)

Taking it from 12v storage and inverting it to 230v AC (with 10% losses)

Taking the 230vAC and converting it back to 12v via the battery charger (with losses)

Putting the 12v into the starter battery (with losses)

 

If your starter battery is 'flat' and your domestic batteries are 'low' due to a day or twos usage whilst moored up, then you may not have enough power to start the engine.

 

Put a split charge relay (VSR) in the system and charge both the starter and domestic batteries from the Solar panels.

Many folk connect the VSR up so it charges the domestics first and then switches over to the starter battery - personally I prefer to charge the starter battery first and then switch over to the domestics, if the Sun isn't shining I'd rather what solar there is goes into the starter battery, if I can start the engine I can always run it to charge the domestics.

 

 

 

Yes, that is a lot of loss. It's fine in this weather because I have loads of spare solar energy. But in the winter months this could become a problem. The relay sounds like a good solution as the cables are already in place from near the controller to the starter battery. I shall look into it more.

 

 

Thank you both.

 

ETA: I suspect this may be a stupid idea but I'll ask it anyway. Could I connect the panels to both controllers and use one each on the domestic and starter batteries? i.e. a loop from one controllers input to the other.

Edited by eid
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36 minutes ago, eid said:

The relay sounds like a good solution as the cables are already in place from near the controller to the starter battery. I shall look into it more.

 

 

Thank you both.

 

ETA: I suspect this may be a stupid idea but I'll ask it anyway. Could I connect the panels to both controllers and use one each on the domestic and starter batteries? i.e. a loop from one controllers input to the other.

Don't be a 'bodging boater', for the sake of £15 'do it right and do it once'.

 

 

https://www.ebay.co.uk/itm/BEP-VSR-Voltage-Sensitive-Relay-Module-Twin-Battery-Charging-Boat-Marine-12v-Van/174257647816?hash=item289290b0c8:g:f8oAAOSwCZFenuz~

  • Haha 1
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11 minutes ago, Alan de Enfield said:

 

So, to understand this more: The live from the controller goes through its fuse, then into the split charge relay. Then two lives come out, one to the domestic bank and one to the starter. The relay switches over at 13.7v.

 

Is that correct?

 

Edited by eid
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36 minutes ago, Detling said:

I would hope that anyone watching the video will install a bit neater than that guy, His set up will fail BSS.

 

It's a real mess isn't it.

 

Looking at that wiring diagram, I think this relay would not only switch the solar, but also the alternator. I have separate alternators for my two banks, so would this be a problem?  I can't think of any but thought I'd ask anyway. I think I would just end up with both alternators charging both banks (when the relay is activated)?

Edited by eid
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Should be no problem as long as they are both 12 volt, probably one will shut down when the batteries are almost full and only taking a couple of amps, so don't wory if you see this on ammeters. The fuses are necessary and those fuse holder wires looked a bit thin for 100 amps.

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20 hours ago, eid said:

Looking at that wiring diagram, I think this relay would not only switch the solar, but also the alternator. I have separate alternators for my two banks, so would this be a problem?

None at all :)

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