How To Get Solar Panel Wired ?

[jonathanA]

Can you buy 8mm2 cable ? 6 or 10 would be the usual sizes I think 

 

eta 8.5 is a standard automotive size 

Edited July 30, 2019 by jonathanA

[WotEver]

7 minutes ago, jonathanA said:

Can you buy 8mm2 cable ? 

Sure. For example.  

8.5mm single here:

https://www.12voltplanet.co.uk/63-amp-single-core-thin-wall-auto-cable.html

 

8mm twin here:

https://www.ebay.co.uk/itm/10m-METER-8mm-8-B-S-TWIN-CORE-DOUBLE-INSULATED-CABLE-COPPER-12V-WIRE-DC-DC-/272200687694

[Alan de Enfield]

8 hours ago, WotEver said:

Sure. For example.  

8.5mm single here:

https://www.12voltplanet.co.uk/63-amp-single-core-thin-wall-auto-cable.html

 

8mm twin here:

https://www.ebay.co.uk/itm/10m-METER-8mm-8-B-S-TWIN-CORE-DOUBLE-INSULATED-CABLE-COPPER-12V-WIRE-DC-DC-/272200687694

That's the stuff - I got a 100m roll from a local 'truck spares' place.

 

Did the fridge wiring, the Solar to battery wiring, and all sorts of bits & bobs.

[NewCanalBoy]

On my solar charger there is a couple of USB outputs, rated at 5V/2A.

 

I assume that if I use these it is using power coming straight from the solar panel ? 

 

What if there is not enough power from the solar panel ? If I have my phone or tablet plugged in is it going to cut in and out depending on what the panel is outputting ? This can't be good for the device being charged ?

 

Is it therefore better/safer to just carry on charger via USB sockets that come straight from the leisure batteries ?

[Murflynn]

your batteries should give a consistent output as long as they are not discharged.  The solar panel will not.  Assuming the USB sockets are fed on a separate circuit from the batteries, they may not function if there is not solar output.  I would charge my phone from the boat's USB.  

[TheBiscuits]

5 minutes ago, Murflynn said:

Assuming the USB sockets are fed on a separate circuit from the batteries, they may not function if there is not solar output.

They aren't.  They are wired to the solar controller's battery connection, so are being fed from the batteries.

[NewCanalBoy]

Thank you, that's what I thought, I'll continue to charge from the USBs which are connected to the battery.

 

Seems odd that there are sockets on the solar panel ?

[WotEver]

8 hours ago, NewCanalBoy said:

Seems odd that there are sockets on the solar panel ?

Why? It’s free charging current.

 

The device being charged couldn’t care less if the charge source disappears and then reappears. 

[Murflynn]

10 hours ago, WotEver said:

Why? It’s free charging current.

 

The device being charged couldn’t care less if the charge source disappears and then reappears. 

it's not free - what goes to the USB doesn't go to the batteries.

 

the device may not care, but you will, if you think your device is charged, and then you find it dies prematurely when you most need it 'cos it didn't receive a full charge.

[tree monkey]

10 hours ago, WotEver said:

Why? It’s free charging current.

 

The device being charged couldn’t care less if the charge source disappears and then reappears. 

I have read, particularly with the smaller panel phone charger type, that if the phone is switched on the intermittent sun out, sun in conditions can discharge the phone.

In effect phone receives a charge, screen lights up, charge drops off backlight stays on briefly, etc.

[WotEver]

3 hours ago, Murflynn said:

... if you think your device is charged...

... you take a look at the charge status, see only 30%, and realise your error. 

 

I have a little solar charger that I plug into a small battery bank when I go on holiday. When I need to charge my phone I do it from the battery bank if there’s no mains handy (say if I’m in town somewhere). 

3 hours ago, tree monkey said:

I have read, particularly with the smaller panel phone charger type, that if the phone is switched on the intermittent sun out, sun in conditions can discharge the phone.

In effect phone receives a charge, screen lights up, charge drops off backlight stays on briefly, etc.

I guess it depends on the phone. My iPhone certainly doesn’t do that. 

[WotEver]

3 hours ago, Murflynn said:

what goes to the USB doesn't go to the batteries.

And that <10W is going to make such a huge difference, isn’t it?

If there’s insufficient sunlight to charge a phone, as you suggest, then it would make zero measurable difference to a 12V 400Ah battery bank. 

[Murflynn]

1 hour ago, WotEver said:

And that <10W is going to make such a huge difference, isn’t it?

If there’s insufficient sunlight to charge a phone, as you suggest, then it would make zero measurable difference to a 12V 400Ah battery bank. 

am I being pedantic when I say it's not free?  ................................. or just being accurate.  

[WotEver]

7 minutes ago, Murflynn said:

am I being pedantic when I say it's not free?  ................................. or just being accurate.  

Why do any of us ask rhetorical questions?

[NewCanalBoy]

I have to leave my boat for 2 months minimum. The two leisure batteries are 3 months old.

 

Should I leave the solar panels charging ? Apparently the controller only takes what it needs but don't know if I trust it ?!

[Chewbacka]

21 minutes ago, NewCanalBoy said:

I have to leave my boat for 2 months minimum. The two leisure batteries are 3 months old.

 

Should I leave the solar panels charging ? Apparently the controller only takes what it needs but don't know if I trust it ?!

I trust mine and leave it on all year, though if it had only cost a tenner I doubt I would.  Is your controller from a reputable make and worth trusting??

Edited October 19, 2019 by Chewbacka

[rusty69]

2 minutes ago, Chewbacka said:

I trust mine and leave it on all year, though if it had only cost a tenner I doubt I would.  Is your controller from a reputable make and worth trusting??

An earlier post suggests its a Victron 20A, so should be fine if installed and fused correctly. My cheap Taiwanese MPPT I didn't trust, so would turn off when leaving the boat.

[Sea Dog]

1 hour ago, NewCanalBoy said:

I have to leave my boat for 2 months minimum. The two leisure batteries are 3 months old.

 

Should I leave the solar panels charging ? Apparently the controller only takes what it needs but don't know if I trust it ?!

I always leave my solar looking after the batteries whatever the time of year. I have 2 x 150w panels connected in series - important, I feel, as connected this way they get to a voltage sufficient to start charging early in the day and stay charging til it's really quite dusky.  My Victron controller records the max and min voltages each day, so I can see that, even through the period of shortest days, the batteries are floating quite happily. This also means I don't need to leave a landline connected, so my mains charger is now only ever connected when we're aboard alongside.

[NewCanalBoy]

Yes, a Victron 20A with an inline 5A fuse. 

 

Thanks, I'll leave it connected.

[Detling]

23 hours ago, Sea Dog said:

I always leave my solar looking after the batteries whatever the time of year. I have 2 x 150w panels connected in series - important, I feel, as connected this way they get to a voltage sufficient to start charging early in the day and stay charging til it's really quite dusky. 

And if one cell in either panel gets shaded by anything the current from both panels is limited to what that cell will pass. In full sun the cell will pass about 5.3 amps in full shade you will only get 1 amp so your 300 watt potential is now about 60 watts, in parallel you would still get 170 watts. The important numbers are amps or watts, voltages are not power.  The extra 30 mins, of almost no current, in early morning and late evening will only give you a few watts, but you can easily lose 100 for an hour in the middle of the day. If you never cruise and are moored in full sun the above will not concern you, but may help others.

[NewCanalBoy]

Watching my solar charger today it peaked at 4.4 amps input. I have a 5 amp fuse so it's close to blowing it.

I didn't think my solar panel rated at 68W could give this much ?

 

Should I go for a slightly bigger fuse ?

[Jen-in-Wellies]

1 hour ago, NewCanalBoy said:

Watching my solar charger today it peaked at 4.4 amps input. I have a 5 amp fuse so it's close to blowing it.

I didn't think my solar panel rated at 68W could give this much ?

 

Should I go for a slightly bigger fuse ?

68/12 = 5.7A, so there is a risk of the solar input blowing the 5A fuse on a very sunny day. We are only just over a month from the summer solstice, so the time of year when the sun appears highest in the sky and the maximum current on a clear day. The fuse is there to protect the wiring. What size cable did you use in the end? Almost certainly safe to up the fuse size unless you are using wire that is silly thin. 7.5, or 10A would be safe from your 68W panel. As earlier in the thread, disconnect the panel from the controller before changing the fuse, or risk blowing up the controller.

 

Jen

Edited May 19, 2020 by Jen-in-Wellies

[LadyG]

On 19/10/2019 at 17:52, Sea Dog said:

I always leave my solar looking after the batteries whatever the time of year. I have 2 x 150w panels connected in series - important, I feel, as connected this way they get to a voltage sufficient to start charging early in the day and stay charging til it's really quite dusky.  My Victron controller records the max and min voltages each day, so I can see that, even through the period of shortest days, the batteries are floating quite happily. This also means I don't need to leave a landline connected, so my mains charger is now only ever connected when we're aboard alongside.

hi S/D, could you explain why series is "better" than  //el in this scenario.

I thought //el would work better all round 'cos any shade knocks 'em down

[matty40s]

5 hours ago, Jen-in-Wellies said:

68/12 = 5.7A, so there is a risk of the solar input blowing the 5A fuse on a very sunny day. We are only just over a month from the summer solstice, so the time of year when the sun appears highest in the sky and the maximum current on a clear day. The fuse is there to protect the wiring. What size cable did you use in the end? Almost certainly safe to up the fuse size unless you are using wire that is silly thin. 7.5, or 10A would be safe from your 68W panel. 

As the weather is now likely to be frost free in the mornings, I doubt that he needs to hurry in adding a bigger fuse. The most dangerous time for suspect installations is late april/early may when you get a frost and then the sun comes up....maximum panel output from multiple panels in series can give some interesting voltages!

Going forward , yes, a slightly bigger fuse.

 

1 hour ago, LadyG said:

hi S/D, could you explain why series is "better" than  //el in this scenario.

I thought //el would work better all round 'cos any shade knocks 'em down

Some of the older E-pever Mppt controllers amongst others, seem to struggle with low light and overcast conditions in winter months. To get them to kick in, sometimes you have to manually remind the controller that it is supposed to be working....this can either be to remove the pos wire and re-insert, or to flash a light on the panel on the roof. It seems worse when the panels are in parallel, series tends to raise the voltage above the kick in work mode more frequently.

[LadyG]

24 minutes ago, matty40s said:

As the weather is now likely to be frost free in the mornings, I doubt that he needs to hurry in adding a bigger fuse. The most dangerous time for suspect installations is late april/early may when you get a frost and then the sun comes up....maximum panel output from multiple panels in series can give some interesting voltages!

Going forward , yes, a slightly bigger fuse.

 

Some of the older E-pever Mppt controllers amongst others, seem to struggle with low light and overcast conditions in winter months. To get them to kick in, sometimes you have to manually remind the controller that it is supposed to be working....this can either be to remove the pos wire and re-insert, or to flash a light on the panel on the roof. It seems worse when the panels are in parallel, series tends to raise the voltage above the kick in work mode more frequently.

OK, I have a modern 40 amp epever/tracer controller [yet] to be wired up, to 2x 275 W panels, thinking a 50 amp fuse would be OK in UK.  It came as a kit with a breaker thing

Edited May 19, 2020 by LadyG