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Hi All,

 

i have reached the end of my road in finding the problem with my solar kit.

The previous owner has installed 2 x 100 watt panels and a PWM, connected in series to charge a 24 volt bank.

I thought the PVM was faulty and i replaced it with a MPPT from EPEVER. It archived a 10-15% increase but still even in bright sunlight without shading and panels directed towards the sun, the panels generate just 95 watt max., generating just 3.5 amp according to the MPPT display.

Should the wattage from the panels not be at least 160 watt?

 

Edited by cutandpolished61
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6 minutes ago, cutandpolished61 said:

Should the wattage from the panels not be at least 160 watt?

 

NO. Panels and controllers are never 100% efficient.

 

The rating of solar panels is based on being on the equator and having the mid-day Sun shining directly down onto the panel.

 

In the UK we are at around 53 degrees North so the Sun is coming in a a much flatter angle so you are getting less 'power' onto your panels.

 

If your panels are angled towards the Sun, in the height of Summer I'd expect around 75% of the rated 'wattage' but with an overall "50% of the year" average at around 50% of rated, and in the other 3 months you will be lucky to average 10-20% % and in the depths of Winter (December to February) possibly as low as 1%

Edited by Alan de Enfield
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Thanks for clarifying Alan. But currently the panels generate just 45% of their rated wattage. There must be a problem somewhere and if i can archive the 75% it would make a big difference to me. I have just the 24 volt fridge connected which i have to switch off at night due to the poor harvest.

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If they are in series, any shade on either panel will cut the output considerably.

 

Similarly if one panel is faulty or low on output the total output will be affected.

 

Try connecting one panel at a time to the controller to see if they both are working.

 

TD'

 

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11 minutes ago, Tracy D'arth said:

If they are in series, any shade on either panel will cut the output considerably.

 

Similarly if one panel is faulty or low on output the total output will be affected.

 

Try connecting one panel at a time to the controller to see if they both are working.

 

TD'

 

Depending on the panel, it may not work with just one. It is supplying a 24V battery bank and the most likely output voltage for a single 100W panel is 19 or 20V. The model of Epever MPPT controller isn't given, but the data sheet I've just looked at says the minimum input voltage is battery voltage + 2V.

Jen

Edited by Jen-in-Wellies
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21 minutes ago, cutandpolished61 said:

Thanks for clarifying Alan. But currently the panels generate just 45% of their rated wattage. There must be a problem somewhere and if i can archive the 75% it would make a big difference to me. I have just the 24 volt fridge connected which i have to switch off at night due to the poor harvest.

I don't know what period you are referring to but here for the last 3 or 4 days it has been really overcast with showers - getting 45% in the last few days is good.

2 minutes ago, cutandpolished61 said:

currently with cloudy conditions the reading is 34 volt, 36 watt, 1.4 amp.

Does the 34 volt not indicate that both panels are working?

Not if they are (say) 40 volt panels (mine are 120volt) don't just think that panels are 'around' battery voltage.

 

What is the voltage rating of the panels ?

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3 minutes ago, cutandpolished61 said:

currently with cloudy conditions the reading is 34 volt, 36 watt, 1.4 amp.

Does the 34 volt not indicate that both panels are working?

No. Its current you want not just voltage.

 

Those figures would suggest to me that there is a significant resistance on the wiring somewhere.

TD'

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22 minutes ago, cutandpolished61 said:

currently with cloudy conditions the reading is 34 volt, 36 watt, 1.4 amp.

Does the 34 volt not indicate that both panels are working?

It does. 34V looks sensible for two panels of this type in series under load. I assume the 1.4A is the output current going to the batteries at 25 or 26V or so, which make sense with 36W being extracted from the panels.

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I am not so sure. The OP quoted a volatge at maximum power not the open circuit or maximum voltage. Twice 17.2 = 34.4V that is what he seems to be getting.

 

What he has not quoted is the charging/battery voltage so the controller may have gone into float too early and that would drop the current the batteries will take. so what is the charging voltage to the batteries, not the panel voltage. Does the current AND VOLTAGE jump up when you put a hefty load on the batteries?

Edited by Tony Brooks
add AND VOLTAGE
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6 hours ago, Jen-in-Wellies said:

Depending on the panel, it may not work with just one. It is supplying a 24V battery bank and the most likely output voltage for a single 100W panel is 19 or 20V. The model of Epever MPPT controller isn't given, but the data sheet I've just looked at says the minimum input voltage is battery voltage + 2V.

Jen

That is exactly what I have, 19 volt panels on a 24 volt system so they have to be in series to drive it. I only use it to maintain the batteries while I am not there but if the same is true of the OP's system then 100% efficiency he would only see around 7 amps at 28 volts, mine is next to nothing but it fully charges the batteries eventually while I am at home and keeps them that way.

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I would say 45w from 2 x 100w panels on a cloudy day is a good performance in Blighty , Output will depend on a lot of factors , Quality of panel , angle and direction of tilt , temperature etc etc but on a normal sunny date expect something around 50-60% of quote max output . My old array tilted to the sun hit 75% of max once fleetingly , My new array with new panels etc and a much better solar controller did hit close to 100% but in british climate around 50% is a good average on a normal non cloudy day . 

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On ‎13‎/‎07‎/‎2020 at 16:42, RufusR said:

I would say 45w from 2 x 100w panels on a cloudy day is a good performance in Blighty , Output will depend on a lot of factors , Quality of panel , angle and direction of tilt , temperature etc etc but on a normal sunny date expect something around 50-60% of quote max output . My old array tilted to the sun hit 75% of max once fleetingly , My new array with new panels etc and a much better solar controller did hit close to 100% but in british climate around 50% is a good average on a normal non cloudy day . 

Many thanks for the info. I've got a 40 amp epever mppt connected to the 2 x 100w panels. No idea how old the set up is but it looks dated. I might have to go for something like 360w to get a better harvest.

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On 13/07/2020 at 16:42, RufusR said:

I would say 45w from 2 x 100w panels on a cloudy day is a good performance in Blighty , Output will depend on a lot of factors , Quality of panel , angle and direction of tilt , temperature etc etc but on a normal sunny date expect something around 50-60% of quote max output . My old array tilted to the sun hit 75% of max once fleetingly , My new array with new panels etc and a much better solar controller did hit close to 100% but in british climate around 50% is a good average on a normal non cloudy day . 

It also depends on the panel type / design. I have 'low-light' panels that are designed for work in the higher latitudes where the Sun strikes the panels at a flatter angle than further South and, get surprisingly good results even tho' they are laid flat.

 

They are 170w, 120v.

 

On a fairly good day in June (16) I got 10.8 amps, at 14.6v and in Feb got 3.3 amps at 14.2v

15-6-16.jpg

18-2-18.jpg

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42 minutes ago, Alan de Enfield said:

It also depends on the panel type / design. I have 'low-light' panels that are designed for work in the higher latitudes where the Sun strikes the panels at a flatter angle than further South and, get surprisingly good results even tho' they are laid flat.

 

They are 170w, 120v.

 

On a fairly good day in June (16) I got 10.8 amps, at 14.6v and in Feb got 3.3 amps at 14.2v

15-6-16.jpg

18-2-18.jpg

Thats very good Alan for a 170w panel  , I have just gone for the " you cant ever have enough solar " approach as living on off Grid linear Mooring . I have 1620 watts on the roof of my 60 foot narrow boat and its like being plugged into shoreline for most of the time .  even will be heating my water ( for the Spring , summer and early Autumn ) once I install all the diversion kit in the next week or so . 

 

 

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