Solar Panel regulator problem

[Chris_Robb]

I have just installed 2 x 85 watt panels (BP) and a Steca PR 2020 regulator.

Great - producing in the weak UK sun some 7 amps. BUT

at the end of day 2 the voltage is standing at 14.3V. The spec for teh Steca says that its float voltage should be 13.8V.

I have checked the set up, and I have it set correctly for Lead acid. (Li) rather than GEL. Batteries are 100% charged as they have been on shore power for the winter.

Any ideas - I presume that leaving batteries at 14.3V will not do them, much good!

Shoudl I put a battery switch into the positive lead from the panels so that I can isolate them when we leave the boat for a week or 2?

Any thoughts/

 

[sarabande]

Stecas need to be connected in a strict order;

1 battery to regulator
2 solar panel to regulator
3 battery to delivery units (e.g. switches / instruments

Before I gave up and read the instructions on my 1010 model, I had all sorts of problems with the output and the data.


They also state that the accuracy of the display is not "comparable" to that of a proper meter !


Have you had any error messages on the display ? There's an error msg if the batt voltage goes over 15.5


If you are using two batteries in parallel, could one of them be slightly under performing ? If the whole dual batt is not 100% saturated charged, then the regulator will still keep trying to put power into both of them - which may affect the one that IS OK. In any case , 14.3 is not a desperately high reading; do you know how at how many amps they are being charged ?

The final specs for the regulator say that for a lead acid battery, it will enable final charging :

float charge at 13.9v
boost charge for 2 hours at 14.4
equalisation charge for 2 hours at 14.7
maintenance charge at 14.7 for up to 30 days if necessary

I think you need to verify

voltage readings with a good meter
both batteries are in peak condition (load discharge test ?)
all connections made in the right order
all connections are without any corrosion


If you are going to switch off the batteries when you leave, you will need to cover the panels to prevent them putting power into a no-load regulator.

 

[Chris_Robb]

Yes - I did (for once) read the instructions! So I did connect up in the right order.

The battery is one large 220AH

I have checked the voltages against a good digital multimeter, and my BM battery monitor - all readings coincide.

There are no error messages - it just shows battery capacity as 100%. with the solar panels folded down - ie vertical, there is 0.3amp going into the battery. This seems to be enough of a current to hold the volts up. I did put a load on by running the fridge - which takes 7 amps. And then allowing the volatge to stabalise again - back to 14.3V.

>>If you are going to switch off the batteries when you leave, you will need to cover the panels to prevent them putting power into a no-load regulator. <<

I would always switch off the batteries when leaving the boat. I was suggesting that I put a switch in the circuit from the solar panels to the regulator. Surely the whole point of the regulator is to stop the panels charging. What does the regulator do with the unwanted electricity? I would hope that I would just be able to leave them on for weeks on end - but perhaps no.... Hence my question about the switch in the circuit. Or do you really have to cover them up?

 

[sarabande]

the regulators generate heat when working normally - which is why you need the air gap around them, to allow the heat to dissipate through the body.

I'm just being ultra cautious with the panels. If they are not connected through to the regulator then they will not generate heat in the regulator. I'm suspicious of some cheaper panels whcih might, under a no-load condition, build up heat internally in the PV cells to an extent that damages them. They are designed to deliver power in sunshine, not to just sit and absorb solar heat.

"Panels are nominally rated at 25 degrees Celsius and can vary by up to 2.5% for every 5 degrees increase in temperature. Thus, as temperature rises, output from the solar panel decreases. " http://www.brightgreenenergy.co.uk/solarpanel_sizing.asp

Panel Internal operating temperatures tend to be rated at a max around 85degs C. (e.g. BP 's PV panels). If a panel is mounted in a way which precludes free air circulation at the back (say, on a cabin roof) and there's little wind, they can easily become too hot to touch easily (which is above 50degs C )

I've made up tie-on covers for mine from an old sail but rarely use them.

 

[William_H]

You might consider disconnecting one solar panel to reduce the charge while you are away from the boat. I have not heard of panels being damaged by being left in the sun with no current load.
I have a pair of 20W BP panels which have survived this last summer with some pretty hot weather (38 in shade) attached flat to my shed roof. No load and no cover and apparently undamaged. good luck olewill

 

[Anonymous]

I have a similar problem with my Pro Star 30 regulator. I think the cause is the boost period. The guys in the lab forget that the sun is modulated by clouds that pass during the day so the batteries get charged, rise to 14.xV for their hour or so, but before the timer can time-out and fall back to 13.6 to 13.9, a cloud passes over, causing the battery volts to drop back to 13.x or even lower if you are drawing a load, resetting the timer for another cycle! So the whole thing repeats itself. You can get a similar effect by drawing a large load with no clouds. My batts rise to 14.4 ish and I don't think that is a big issue for short periods. I'm not sure you are going to do any better.

I wouldn't dream of putting a switch in the circuit of covering up the panels. The whole point is for the regulator to control this 356/365. For example, you'll leave your bilge pump on auto, and the fridge on during the season, so you want the panels to keep the batteries topped up. If you have flooded lead acid batteries you shouldn't have a problem as you can add water but in any case unless the temperature of the batteries gets to around 45C+ you will find that the current at 14.4V is pretty trivial and you might not lose much water at all. I do have a problem in the Med after a long passage when the batteries can reach 50C and at 14.4V and above I can get 8A or more through them (560Ah domestic bank) and that costs water.

I would thoroughly recommend a fixed digital meter to measure current and voltage. I have the BEP which also has a bilge pump monitor (tells you how many bilge pump cycles and total pump run time since last reset) which is a terrific confidence builder, knowing that you have no leaks. I find the battery contents part of the BEP rather pointless. I use the voltage tables that have been published here many times and they work fine - you get to know your batteries anyway. Still, for volts and amps and bilge monitoring in a decent-looking panel meter, the BEP is worth the money. There might be better choices now, I bought mine in 2005.

 

[vyv_cox]

It takes my 125 watts of solar power a very long time indeed for the controller to go to the float voltage. The figures for my setup are very similar to yours. During the season, fridge running 24/24 and various other consumers, I do not recall the voltage ever dropping down from 14.3 or 14.4 to 13.8. Only ashore at the end of the season, with fridge and everything else turned off, did I see the controller flicking between the upper and lower voltages. This despite an indicated current up to about 7 A in October.

For winter purposes of keeping batteries up to maximum voltage I disconnect the main panels and go back to my original 38 watt one on the coachroof, through the same controller. This has worked well now for many years. 3 x 105Ah batteries, 2 domestic and one starter.

 

[alan]

I also have a Steca 2020, and I consider 14.3/14.4v normal when batteries are "fully" charged. I suspect the fact is that due to clouds, shadows e.t.c. that the batteries never really achieve 100% charge. I find the most useful monitor on the Steca to be the SoC indication and I use my BEP volt/amp meter for keeping an eye on the state of the batteries.
In my opinion your regulator is working 'normally'. Also, isolating the panels with a switch somewhat detracts from one of the reasons for installing in them in the first place.

Alan.

 

[Chris_Robb]

David - thanks for your lengthy reply. Judging by other comments here, it looks like what I am experiencing is the norm. Perhaps the people who write the manuals ought to read this forum!

By the way, I have a Nasa BM battery monitor, which I would not be without. The Steca and the BM agree precisely on the voltage and amps in.

Chris

 

[Chris_Robb]

Thanks for that Vyv.

New fridge which is actually half deep freeze and half fridge, functions wonderfully, and the 2 BP 85 watt panels seem to supply all the power needed while the fridge was still going full blast cooling for the first time. And that was in the UK, with not wall to wall sunshine.

 

[Chris_Robb]

Alan

Thanks for the reassurance.

Chris

 

[beachbum]

[ QUOTE ]
...I have it set correctly for Lead acid. (Li)...

[/ QUOTE ]
- are you quite sure about that? 'Li' is the symbol for Lithium - not Lead. Seems a bit odd if it really does indicate "Lead/acid".

 

[Chris_Robb]

[ QUOTE ]
[ QUOTE ]
...I have it set correctly for Lead acid. (Li)...

[/ QUOTE ]
- are you quite sure about that? 'Li' is the symbol for Lithium - not Lead. Seems a bit odd if it really does indicate "Lead/acid".

[/ QUOTE ]

Absolutley - Lithium batteries are specifically not supported! Others on this forum say that the voltages I am experiencing are correct.