You are logged in as a guest. 
  Home Forums Home  Search our Forums Search our Forums    Log in to the Forums Log in to the Forums  register Register on the Forums  

 Forums ->  Motorhomes -> Motorhome Matters
Jump to page : First 1 Last
Format:  Go
Max solar watt?
AuthorMessage
userweldted
Posted: 3 January 2019 9:40 AM
Subject: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Hi all happy new year. Having trouble getting the best from my solar panel time to renew.
I had 300 watts to a single output Mppt solar boost 2000e. Replaced the controller with a Votronic 350 Mppt dual out put. Panels on checking are 11 years old. Was only getting 17.4 volts from panels and very low amps. Aware it's Jan but near Limoges in bright sunlight batteries at 88% less than 1 amp with hab power off. Changed the wiring around to have 260 watt wired in series to produce 34 volts but charging rate just 1.2 at midday yesterday bright cold clear view of sky. Question is controller is rated max 350 watts was new Sept 18. Have room for three 120 watt panels @ 18.7 volts am I pushing it with the 350 controller.
user747
Posted: 3 January 2019 9:47 AM
Subject: RE: Max solar watt?
 


Epic contributor

Posts: 1953
10005001001001001002525
Location: Tyne and Wear - Burstner Delphin Performance T821


I am no expert but 18.7 volts from a new panel seems low to me. I have bought 2 solar panels of good quality and there rated output is over 20 volts (at least 21 if I remember correctly). They were not cheap ebay ones and cost me a bit more to buy. The oldest (90 watt) is about the same age as yours and I use it freestanding if my roof mounted 100 watt panel is not doing much on dull cloudy days. It still produces 5.5 amps in ideal conditions.
userweldted
Posted: 3 January 2019 10:18 AM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Thanks for your reply the ones I am looking at are photo universe rated 20.4 volts 120 watts just wondering if my 350 watt controller would handle 360 watts?
userspirou
Posted: 3 January 2019 10:33 AM
Subject: RE: Max solar watt?
 


Gets involved

Posts: 263
1001002525
Location: SI, PVC X250 Citroën


Still no luck figuring out if you have a defective controller or panels? Even with my 120W panel I can get over 1A on a sunny winter day so something definitely weird with your new setup.

Any chance you could test out each panel individually? If you can get the same(ish) amps from a single panel it might be that you don't actually have the 350W model but the smaller one (likely in the same box, just different internals).

I'd suggest you park next to someone friendly with a solar panel on the roof and temporarily switch out the controllers then see what you both get before/after.
userweldted
Posted: 3 January 2019 10:58 AM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


I am still concerned that the fault may lay with the controller, it is clearly labelled as a 350 watt unit. But they want me to send it back for checking which is not really an option as away in van. I have checked each panels voltage separately all show 17.4 volts. Only .1 volt less than on the label. Haven't tried each individual ones output as following a suggestion posted earlier I have doubled up the voltage to 34 but this didn't show much if any improvement. If I leave the hab electrics on the computer shows 0.7 to 0.8 amps discharge. So the panels over 24 hrs do not even keep up.
userspirou
Posted: 3 January 2019 11:10 AM
Subject: RE: Max solar watt?
 


Gets involved

Posts: 263
1001002525
Location: SI, PVC X250 Citroën


Any clues what the drain is? Seems too much for any stand-by.
userweldted
Posted: 3 January 2019 12:01 PM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


2012 Aspire 255 tracker is powered by hab circuit, lights take 0.2 amp as they have dimmer switches, water system has two solenoid valves they seem to take a small amount as fuse sparks when Put in about 0.1 amp always had this drain from new. Shows 0.1 discharge when hab elec turned off. Separated the panels into two banks one shows 0.8 charge other 0.9 charge.

Edited by weldted 2019-01-03 12:22 PM
user747
Posted: 3 January 2019 12:30 PM
Subject: RE: Max solar watt?
 


Epic contributor

Posts: 1953
10005001001001001002525
Location: Tyne and Wear - Burstner Delphin Performance T821


weldted - 2019-01-03 10:18 AM

Thanks for your reply the ones I am looking at are photo universe rated 20.4 volts 120 watts just wondering if my 350 watt controller would handle 360 watts?


360 watts will probably only be achieved in laboratory conditions. I wold go for it if I were you.

As has been said, your drain seems a bit on the high side and needs looking at. It will not be noticeable any time except for Winter conditions but seems like a fault somewhere, a fault that could get worse.
userspospe
Posted: 3 January 2019 3:32 PM
Subject: RE: Max solar watt?
 


Forum master

Posts: 2182
2000100252525
Location: Stockport Autosleeper Warwick Duo 2.2 130bhp


weldted - 2019-01-03 9:40 AM

midday yesterday bright cold clear view of sky.



Was the panel in the sun? A view of the sky, no matter how blue will not give you much by way of an output. The panel itself must be in the sun, without any shadows.
userPaul-
Posted: 3 January 2019 4:38 PM
Subject: RE: Max solar watt?
 


Has lots to offer

Posts: 434
10010010010025
Location: Yorkshire


Are you measuring the voltage at the panel or at the controller, if at the controller have you considered voltage drop on the cable.
userStuartO
Posted: 3 January 2019 4:54 PM
Subject: RE: Max solar watt?
 
Forum master

Posts: 3651
200010005001002525
Location: Suffolk, Hymer B674 2006


My solar panels are now 12 years old and about four years ago they failed (over a winter storage period) and I took them back to supplier/fitter, Solar Solutions. They replaced the diodes (? rectifiers) in the black boxes behind each panel and this gave them a new lease of life.
userweldted
Posted: 3 January 2019 7:32 PM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Sun was very bright no obstructions.

Voltage measured at panels, 6 mm solar cable 0.2 volt between panels and controller 3.7 mtr cable run.
Today 34.7 at panels 34.5 at controller 13.8 battery side of controller 13.7 at batteries 1.2 mtr run.
userspirou
Posted: 3 January 2019 8:43 PM
Subject: RE: Max solar watt?
 


Gets involved

Posts: 263
1001002525
Location: SI, PVC X250 Citroën


Given the history and new information I can't get over the feeling your controller is limiting output. Whether because of a fault or as I suspect, different internals than what is says on the box. It's not uncommon for different products to share enclosures and whoever assembled it could have made a mistake grabbing the wrong part. If this information is correct, the same "box" with different print is used for 9 different models so my theory is not completely ludicrous and mistakes do happen:
https://www.votronic.de/index.php/en/products/solar-technology/charging-controllers

Edited by spirou 2019-01-03 8:44 PM
userweldted
Posted: 4 January 2019 12:15 AM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Thanks for that Spirou, I also suspect that the fault may lie with the controller, before changing over I always seemed to get a higher charging rate from my Solar Boost 2000E. Having upgraded the wiring from the panels to the controller and from there to the batteries, two new Youasa L36-EFB 100 amp batteries. Fitted an earth wire onto the alternator body directly from the hab batteries and same to engine battery. Some what disappointed. When driving batteries recover very quickly, wether just from alternator or using my set up which uses an inverter from the engine battery to run the new Victron 30 charger. Re the controller even if I have the hab batteries at 95% the second terminal from the controller for charging the engine battery reads a higher voltage when the sun is shining. And the 80% and 100% lights on the controller never light up. As the only offer from Votronic is that I send it back for checking I am going to have to buy another one and get it delivered to France fit it and send the other one back as we are not back in the UK until May.
Many thanks to all who posted I am going to pull the fuses tomorrow with the panels isolated to check on the current drain, but I know some of it is down to the LED strip lighting has illuminated dimmer switches which consume a small amount of current.
userspirou
Posted: 4 January 2019 5:19 AM
Subject: RE: Max solar watt?
 


Gets involved

Posts: 263
1001002525
Location: SI, PVC X250 Citroën


How about finding a caravan/nautical shop (should be easy enough in south of france) and test fitting any other controller that can handle your 300+W of panels? It takes less than 5min to switch over 4 wires and it will tell you exactly where the problem is. Even better if it's a victron (bluesolar) and you can check all the parameter on your phone.

Edited by spirou 2019-01-04 5:20 AM
userweldted
Posted: 5 January 2019 10:06 AM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Bit the bullet and ordered a new controller, our nearest Motorhome dealer (Limoges) wanted min two hour labour to check it, so ordered a new one as not much difference in price so will have a spare it it's not the problem.
Also ordered the 420 mpp as going to replace my panels with three 120 watt ones if needed and the present one although labled 350 mpp states max 320 watts input. We are fairly heavy uses of 12 volt and as you get older travel less so probably the road to go down. My mains charging set up is great if on the move every few days or we have a eu10i for back up but very respectful of others in its use plus solar is preferred. Many thanks to all that replied will update when new one fitted but must say dissapointed with the customer support from where I bought it, as never got a direct reply to why the 80% and battery full lights never lit up even when batteries had been on mains hook up for two days showing 14.4 volts and 100% charge.

Edited by weldted 2019-01-05 10:07 AM
userPaul-
Posted: 6 January 2019 9:58 AM
Subject: RE: Max solar watt?
 


Has lots to offer

Posts: 434
10010010010025
Location: Yorkshire


weldted - 2019-01-03 7:32 PM

Sun was very bright no obstructions.

Voltage measured at panels, 6 mm solar cable 0.2 volt between panels and controller 3.7 mtr cable run.
Today 34.7 at panels 34.5 at controller 13.8 battery side of controller 13.7 at batteries 1.2 mtr run.



Sounds like a decent setup and is pointing to the controller, I hope the new one sorts it out

I use Morningstar controllers after once having a Steca controller go down, this let all the panel power go to the battery and cooked it, at least yours is the other way
userplwsm2000
Posted: 6 January 2019 12:11 PM
Subject: RE: Max solar watt?
 
Gets involved

Posts: 249
10010025
Location: Somerset. Frankia i640SD


weldted - 2019-01-03 7:32 PM

Sun was very bright no obstructions.

Voltage measured at panels, 6 mm solar cable 0.2 volt between panels and controller 3.7 mtr cable run.
Today 34.7 at panels 34.5 at controller 13.8 battery side of controller 13.7 at batteries 1.2 mtr run.


Just a thought - Do you have the (optional) battery temperature sensor fitted on the Votronic? If so, try disconnecting it to see if this increases the solar charge voltage.
This sensor is a PTC thermistor and should read about 2Kohms at room temperature. If the sensor reads a bit high, the controller will think the battery is too hot and reduce its output voltage (and charge). It only needs to be around 2.4Kohms for the controller to go into an over-temp.shutdown. With the sensor disconnected, the controller assumes the battery is at 20 degrees C and sets its output accordingly.
userweldted
Posted: 6 January 2019 3:54 PM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Thank you for that, I have the temp sensor fitted, did try disconnecting it, made no apparent difference over two days.
userweldted
Posted: 9 January 2019 2:26 PM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


Still waiting for new controller, checked today outside air temp +3 batteries in external locker. Temp sensor is disconnected. Resistance read 1.17 ohms. Batteries show on the Solar Computer 98% from Solar Panels into controller 38.4 volts, from controller to batteries 12.9 volts, indicated charge to batteries with hab power off 0.5 amps. Sky overcast but bright. Indicators lights on controller that should show state of charge at 80% and battery full are not illuminated mpp light steady but dull. Turned on 30 amp Victrom charger shows charge rate of 4.6 amps and falling, 80% light comes on very bright batt full light on but not so bright.

userplwsm2000
Posted: 9 January 2019 4:59 PM
Subject: RE: Max solar watt?
 
Gets involved

Posts: 249
10010025
Location: Somerset. Frankia i640SD


weldted - 2019-01-09 2:26 PM

Still waiting for new controller, checked today outside air temp +3 batteries in external locker. Temp sensor is disconnected. Resistance read 1.17 ohms. Batteries show on the Solar Computer 98% from Solar Panels into controller 38.4 volts, from controller to batteries 12.9 volts, indicated charge to batteries with hab power off 0.5 amps. Sky overcast but bright. Indicators lights on controller that should show state of charge at 80% and battery full are not illuminated mpp light steady but dull. Turned on 30 amp Victrom charger shows charge rate of 4.6 amps and falling, 80% light comes on very bright batt full light on but not so bright.


A resistance of 1.17 ohms suggests that the sensor has gone short circuit. I am not sure if this could damage the solar controller (but I think it is unlikely as it would be such a bad design if it did!).

It may be just a coincidence but the solar controller will limit its output to 12.8V if it detects a "hot" battery (sensor reads greater than 50 deg C).
When you get the new controller, I would be tempted to leave off your temperature sensor for now unless you have Lithium batteries.
userweldted
Posted: 9 January 2019 6:17 PM
Subject: RE: Max solar watt?
 
Has lots to offer

Posts: 475
100100100100252525
Location: Elddis Aspire 255


My thoughts as well, the controller and regulator were bought as a package so will be sending them both back. Been advised new controller is due tomorrow so hopefully will get somewhere?

Many thanks.
Jump to page : First 1 Last
Printer friendly version
E-mail a link to this thread
Jump to forum :


(Delete all cookies set by this site)(Return to Homepage)

Any problems? Contact the administrator