Solar panel/battery advice

photonic universe sell 160 solar kits with only 10amp controller so don't think that's the problem.

https://www.photonicuniverse.com/en/catalog/full/184-160W-12V-solar-charging-kit-10A-controller-5m-cable-for-camper--caravan--boat.html

I wouldn't be happy with this. To estimate the rating of a controller you divide the total solar panel wattage by the battery voltage and add 25 percent which for a 160w panel comes to near enough 17 amps. Even without the 25 percent margin the current is just over 13 amps! A 20 amp controller is required.

peedee

Ohm’s Law : Amps x Volts = Watts So even though I know not a lot about solar panels PD makes sense as the current would easily exceed 10amp even when the battery is near full charge

I agree 10A seems a bit "near the knuckle" but don't forget solar panel output voltage is something like 18-21V so 160/18 is less than 10A, and you won't get absolute peak output from the panel unless the light is coming perpendicular to the panel, so by the time you factor all that in it'll be OK... Just don't go to one of the Tropics (Cancer or Capricorn) on midsummer's day!

Not reassuring to me, actually raises other concerns.

At the higher current "bulk" phase with an expected output of 14.6 volts the current will be about 11 Amps, even higher, 11.6 A if using as low a bulk phase as 13.8 volts.

Is the efficiency of the controller low enough to keep within the rating, or the panel not as rated?

The output of a solar panel is about 20 volts, so the current from 160 watt panel will be nearer 8 amps maximum. Given the dire efficiency of the controller I doubt that the current will increase much, if any when at the 14 plus volts of the output. 

My 100 watt panels 10 amp controller give a maximum output of about 5.5 amps. I think that represents about 75% efficiency which is quite good.

When I fitted a 135w panel to my last van, I tried to buy a 20amp controller.  The supplier refused to sell me one saying a 10amp one would be fine.   He said that the amp rating is based on the input not the output amps. I have no reason to disbelieve him as it saved me money. 

Also as a general observation it seems strange that the OP states that he changed the battery and has a problem since then.   People leap to the conclusion it must be the controller.  Possible but not likely imho

Perhaps you could ring them peedee and put your view to them and then let us all know what there reply is.

You cannot work Ohms law using battery voltage to determine the panels output in amps.

160w panel is 'Peak power' and will never be realised in this country, the amps will be calculated by the maximum voltage output of the panel which is around 18-20 volts. If the voltage drops due to lack of sun the 160w output will also drop, hence so will the amps. In reality it will never exceed 8/9 amps and even less due to inefficiency.

10 amp controller is fine.

You cannot work Ohms law using battery voltage to determine the panels output in amps.

The 10 amp rating is the output of the controller not the input! At least that is the norm. There are so many variables in determining the output of a panel, not least the intensity of light and the angle onto the panel, that using panel watts divided by battery volts is just a way of estimating controller requirements, another is to divide the watts by 16.5? Either way I would not be happy with a 10amp controller on a 160watt panel. To me a 10amp controller is I assume leaving very little margin to allow heat to dissipate unless it is not a very efficient panel.

peedee