Solar questions

[Camper634]

Could anyone please advise on the following?Can dirty panels have a big effect on your solar efficiency and is 1 amp an acceptable volt drop from panel via the regulator to the battery.Cable is 6mm and the length around 4 metres.My system of 1 x 120 panel and 1 x 80 panel were generating about 4 amps before I cleaned them and afterwards nearly 6 !That was at around half past nine this morning so by midday I’m hoping it will be maybe up to around 8.Thank you for any input,much appreciated.

 

[Richard n Ann]

Do you mean 1 volt drop through the regulator? The regulator will drop the voltage to suit the battery so if it's working OK... It's OK.
I think you've answered your own question about cleaning it. Your amperages sound about right. They may start reducing by noon as the battery becomes fully charged ?

 

[Lenny HB]

Your cables are fine, for your set up 4 mm cable would be adequate.
Input to the regulator is normally 17 to 18 v and the output at full charge 14.2 to 14.4v, and in float mode 13.6 to 13.8v.

If you are getting a 1v drop across 4m of 6mm sq cable you must have a poor/ high resistance connection.
The regulator should be as close to the batteries as possible.

To make that much difference your panels must have been really dirty, my 300 watts of panels were covered in sand last year cleaning them only gained 1 amp.

 

[autorouter]

is 1 amp an acceptable volt drop from panel via the regulator to the battery

Do you mean 1 volt? Usually there is a voltage drop of at least 4V between the panel and the battery, and for MPPT controllers it is often much more. 35V to 14V is common.

 

[Camper634]

No I did mean 1 amp.i clipped the cable on the roof where the 2 panels are connected in parallel and my ammeter read 5.2 Amps.At the other end just before it entered the regulator it read 6.0.Admitidley i was using 2 different ammeters but I did zero them both.I will check again using the same meter for both readings.The panels weren’t particularly dirty I didn’t think but there was a film on them both.The difference was instant though.

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[Richard n Ann]

No I did mean 1 amp.i clipped the cable on the roof where the 2 panels are connected in parallel and my ammeter read 5.2 Amps.At the other end just before it entered the regulator it read 6.0.Admitidley i was using 2 different ammeters but I did zero them both.I will check again using the same meter for both readings.The panels weren’t particularly dirty I didn’t think but there was a film on them both.The difference was instant though.

That's because it's going through the regulator, it's not the same cable.
The amperage is higher at a lower voltage, but it will be the same wattage if you do the volts x amps calculation (or similar wattage) ?

Edit: ignore the above, I must read the thread properly before replying ?
My guess is that one ammeter is reading out of true.

 

[autorouter]

No I did mean 1 amp.i clipped the cable on the roof where the 2 panels are connected in parallel and my ammeter read 5.2 Amps.At the other end just before it entered the regulator it read 6.0.Admitidley i was using 2 different ammeters but I did zero them both.I will check again using the same meter for both readings.The panels weren’t particularly dirty I didn’t think but there was a film on them both.The difference was instant though.

If it's the amps along a single cable, there is no simple explanation, it should be the same at all points along the cable. Two different meters might give that much difference, especially if you are using the 200A range. Can you compare the readings for example at the regulator end, both meters reading at the same time? Another explanation might be a dodgy contact, causing the amps to fluctuate, and you measured at different times.

 

[Camper634]

Sorry the readings I stated were ar.e about face.On the roof the readings were about 0.8 amps higher than it was at the other end of the same cable.I will check again using the same meter at both points.I am amazed how much difference cleaning the panels seems to have made though.

 

[autorouter]

Another explanation might be a dodgy contact, causing the amps to fluctuate,

Maybe that's part of the reason for the increase. Your cleaning activities disturbed the wiring so the contact got better.