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Quick numpty question regarding solar.


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I have a 175W panel. I’m considering getting an additional panel to charge my 12v batteries. 
Using the controller in the photo what’s the maximum I can get? It says max input 260W on the side, but am I correct in thinking I can over size because the panels will never reach the maximum input?

 

Thanks. 

 

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What model is it?

 

The manual will be available online, and should state the maximum power and voltage of panels you can connect to it.

 

My epever is deliberately over panelled but not more than the maximum it can cope with.  In theory this should extend my solar season in spring and autumn, but I only fitted the new controller in May so I don't know how well it's going to work yet!

 

Basically, yes the controller can throttle excess panels but only up to a point and you mustn't exceed it's maximum voltage or the magic smoke will come out.

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28 minutes ago, Goliath said:

another 100W shouldn’t be a problem then?

 

I included wrong photo, wrong side.

It says max 260W

 

 

It also says that your maximum allowed PV input voltage is 150v. That would be impossible, from a 260w panel. I think the extra panel will be ok. 

 

 

Edited by Higgs
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4 minutes ago, Higgs said:

 

It also says that your maximum voltage is 150v. That would be impossible, from a 260w panel. I think the extra panel will be ok. 

 

 


Ok. 
I have been given 2 x 100W panels and a controller but I don’t want to wire up an additional system. 
So I’ll add 100W to what I’ve got and see how it gets on this winter. 
 

thanks. 

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You need to get a panel with similar characteristics to you existing panel for the best performance.extra

 

If the extra panel is connected in series with your existing panel make sure the two panels have similar maximum power currents (Imp).

 

If the extra panel is connected in parallel with your existing panel make sure the two panels have similar maximum power voltages (Vmp).

 

If they are not matched then it is likely that the lowest voltage panel in parallel or the lowest current panel in series will effectively pull down the performance of the other panel and you will not be able to harvest the expected power.

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1 minute ago, Goliath said:


Ok. 
I have been given 2 x 100W panels and a controller but I don’t want to wire up an additional system. 
So I’ll add 100W to what I’ve got and see how it gets on this winter. 
 

thanks. 

 

Most regular 100w panels can, under the right conditions, can produce about 18.6v. You will be well within the limit of the unit. 

 

 

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13 minutes ago, Higgs said:

 

It also says that your maximum allowed PV input voltage is 150v. That would be impossible, from a 260w panel. I think the extra panel will be ok. 

 

 

 

My 170w panels are 120 volt, if I wired 2 together I could be getting 240v.

 

Why do you think 150v is impossible ?

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1 minute ago, Alan de Enfield said:

 

My 170w panels are 120 volt, if I wired 2 together I could be getting 240v.

 

Why do you think 150v is impossible ?

 

Add the voltages up of 4 regular 100w panels and it is still well under the limit of his controller. I run 4x100 on two separate controllers, I'd be happy, if they managed the expected 36 volts from two panels in series. 

 

 

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8 minutes ago, Higgs said:

 

Most regular 100w panels can, under the right conditions, can produce about 18.6v. You will be well within the limit of the unit. 

 

 

 

Totally incorrect information.

 

Solar panels have two main characteristics, Volts and Watts (& hence amps)

 

There is no reason why 100w panels should be 18.6v

 

 

Note the panel output voltage 18th February (91.6v), and again a few weeks later (103.1v)

 

 

 

 

 

 

 

 

 

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Edited by Alan de Enfield
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5 minutes ago, Alan de Enfield said:

 

Totally incorrect information.

 

Solar panels have two main characteristics, Volts and Watts (& hence amps)

 

There is no reason why 100w panels should be 18.6v

 

 

Note the panel output voltage 18th February :

 

And again (later) in the year

 

The maximum voltage is fairly standard at 18.6v. More with an open, no load, circuit. Delivering about 5amps. Optimal. 

 

 

 

Edited by Higgs
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6 minutes ago, TheBiscuits said:

 

What's the other controller, and can it handle all 3 panels, assuming they are matched?

 

Photos of the labels on the back of the panels please.

That’s something that’s crossed my mind too. 
I’ll have to get back to you on the photos and info of other controller. 

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4 minutes ago, Higgs said:

 

The maximum voltage is fairly standard at 18.6v. More with an open, no load, circuit. Delivering about 5amps. Optimal. 

 

Will you buy @Goliath a new controller if your advice is wrong?  I want to see the specs for all 3 panels before advising how to connect them up.

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7 minutes ago, Higgs said:

The maximum voltage is fairly standard at 18.6v. More with an open, no load, circuit. 

 

 

You have no idea what panels he has. Until he identifies the panels and their specifications your advice is potentially dangerous.

It may turn out that you are correct, but it would be by luck rather than knowledge or good judgement.

1 minute ago, Higgs said:

 

The calculations are based on Watts divided by Voltage. 100 watts/18.5v = amps.

 

 

 

ASSUMING they are 18.5v panels, which they may not be.

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1 minute ago, Alan de Enfield said:

 

You have no idea what panels he has. Until he identifies the panels and their specifications your advice is potentially dangerous.

It may turn out that you are correct, but it would be by luck rather than knowledge or good judgement.

 

There is a lot of standard output panels around. I'd guess his 100w panel is no more than 18.6v, 5amps.

 

 

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2 minutes ago, Higgs said:

 

There is a lot of standard output panels around. I'd guess his 100w panel is no more than 18.6v, 5amps.

 

 

 

As I say, you may be correct, but it would only take a couple of the Bimble 120v ones (like mine) and he's up the creek.

Better to work on facts than what is 'standard'.

Someone will be using 'non-standard' panels.

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3 minutes ago, Alan de Enfield said:

 

As I say, you may be correct, but it would only take a couple of the Bimble 120v ones (like mine) and he's up the creek.

Better to work on facts than what is 'standard'.

Someone will be using 'non-standard' panels.

 

There should be a sticker on the back of the panels. And if they don't have diodes, they will be even less efficient, as they maintain a better output when the panel is partially shaded in one area or another. 

 

 

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