Matching Victron solar controller

[gmakhs]

Originally Posted by daveNZ

I’m getting nervous about a Victron mppt solar regulator 75/15 I have just bought for a 150W 17V Pmax panel.
so the reg. needs batt+5v to start! can you trigger it by turning on some load to lower the batt. voltage? e.g. turn on a pump.
How long (milliseconds?) at batt+5V does it take to get the Victron reg.started?

Replace the panel with 2 X 80 watt you will be happier .

[daveNZ]

The 150 was much better $/W and size, so I’d like to make it work.

[gmakhs]

Originally Posted by daveNZ

The 150 was much better $/W and size, so I’d like to make it work.

Then give it back and buy from.somewhere else , 2 X 80watt should not cost more than 80 euro each .

I used to have a 100 watt 18 volt solar before I change to 2x60 watt , it will work but you will get seriously better performance using 2 .

Vixtron recommend 72 cells in the manual as well and they you are better with 2 lower wattage solars that 2 big .
If you don't wanna or can't buy 2 lower wattage , buy a 24 volt panel

[Pete7]

Originally Posted by daveNZ

The 150 was much better $/W and size, so I’d like to make it work.

Can the panel go back? We have a Victron 15/75 connected to a 150w panel with a Pmax of 20.2v. Works brilliantly and am really pleased I changed from a 80w with PWM set up to the MPPT.

I do like the display from the Victron to see what is going on.

Pete

[noelex 77]

Originally Posted by daveNZ

I’m getting nervous about a Victron mppt solar regulator 75/15 I have just bought for a 150W 17V Pmax panel.
so the reg. needs batt+5v to start! can you trigger it by turning on some load to lower the batt. voltage? e.g. turn on a pump.
How long (milliseconds?) at batt+5V does it take to get the Victron reg.started?

Before you panic too much remember the 17v is Vmp. Before start up there will no current so it is the Voc which has to 5v over the battery voltage. Voc will be a few volts over Vmp.

It is not clear if this is practical problem or just a theoretical concern.

I suspect there will be occasional examples where the start up is late enough to be a practical problem, but this will not effect many users. However, it would be great to have some feedback from those using Victron controllers with 12v panels if the start up is at an appropriate time.

The concern is only for “12v” panels connected in parallel to Victron controllers.

The situations where it is most likely to be a problem are:

If there is another charge source, such as wind.
If the batteries are reasonably charged with little or no overnight load
If the “12v” panel has lower Voc than average
If conditions are hot
If the panels have poor ventilation
If there are permanent isolated shaddows on the pannels in the morning

It is is easy to check if your installation is starting up at the correct time. Just note the current at start up. Ideally it should be 0 A or only a very low positive value. If you have the Bluetooth option you can see the panel voltage rise in the morning and start up will occur when the panel voltage is 5v over the battery voltage.

[conachair]

Originally Posted by daveNZ

I’m getting nervous about a Victron mppt solar regulator 75/15 I have just bought for a 150W 17V Pmax panel.
so the reg. needs batt+5v to start! can you trigger it by turning on some load to lower the batt. voltage? e.g. turn on a pump.
How long (milliseconds?) at batt+5V does it take to get the Victron reg.started?

Sounds like a 36 cell panel, my 100w ones have a Vmpp (max power) of about 18.7v & Voc (open circuit) of 21.6v. As mentioned above if there's not enough sun to push the open circuit voltage up above 20v then there isn't enough sun to do any real charging so the 5v needed for start up is no big deal in the real world. Image below is actual figures of a victron 10/75 starting up with a mains charger holding the battery voltage at float >>

[gmakhs]

During my trip down to West Africa , I decided to make a test on my solar array both tests where concluded with 100 watt and not much cloud shading .
With one 100 watt solar panel the charge would start around 9 00 overa1 amp and finish or being under one Amp at 17:00
I had no charge when the panel was shaded by Genoa .

With 2 x50 watt the charge would start at 7 :00 and being under 1 amp at 19:00
The charge current wasn't effected so much with the boat movement.
I had better performance 1 to 1.5 amp when both panels where shaded by the Genoa (usually 14 to 15h)

The disadvantages of panels in series is when only one panel is shaded and the other not something that doesn't happen to my setup (at least not to a noticeable level .

P.S every boat is different so you can test your own with series or parallel connection but if vixtron suggest 72 cell go with 72 and not 36 because you are clearly losing performance

[Pete7]

Originally Posted by noelex 77

It is is easy to check if your installation is starting up at the correct time. Just note the current at start up. Ideally it should be 0 A or only a very low positive value.

That could be a 04.30 am start for us in June.

From a post on another forum I wrote this for some reading in early Aug 17:

"the 150w panel was providing 6 amps at 8am in the morning, 7amps at 9am and still rising"

The panel was tilted 15 deg downwards towards the bow and the yacht faced East when the reading were taken.

[daveNZ]

thanks for those useful notes Noelex77. Yes the Voc is 20.5 so hopefully I'm OK. I'll try and do some tests. Panels are not so cheap in NZ.
NZ$500 for a 150W.
A supposedly top quality one (not even Solbian) is NZ$500 for 100W
I only use 15AH overnight and 50-60/24Hrs so there's plenty of panel I feel.

If I can test and get something useful I'll report back.

[gmakhs]

Originally Posted by daveNZ

thanks for those useful notes Noelex77. Yes the Voc is 20.5 so hopefully I'm OK. I'll try and do some tests. Panels are not so cheap in NZ.
NZ$500 for a 150W.
A supposedly top quality one (not even Solbian) is NZ$500 for 100W
I only use 15AH overnight and 50-60/24Hrs so there's plenty of panel I feel.

If I can test and get something useful I'll report back.

There are some Chinese sellers from AliExpress shipping in New Zealand with no taxes , to 1/5of the price .

[daveNZ]

Originally Posted by gmakhs

There are some Chinese sellers from AliExpress shipping in New Zealand with no taxes , to 1/5of the price .

Wish.com who sell a nz$25 iphone cable for nz$3, are nz$300 for 200Watts. So cheaper but not 1/5th. Local warranty support is worth something, but yes they are cheap.

[daveNZ]

Connected new 150W panel and Victron 75/15 Smartsolar mppt reg with all defaults. Yes it waits till PV voltage reaches batt+5V, and shows no solar power during that stage (0Watts). But as soon as it goes over that, the solar power shows as e.g. 7W on a very cloudy sky. Continues to run even though PV voltage hovers around 15V. Brilliant.
My 150W panel has 32 cells.

[john61ct]

So no actual charging amps available until the voltage climbs high enough anyway.

[daveNZ]

Originally Posted by john61ct

So no actual charging amps available until the voltage climbs high enough anyway.

Correct. The phone shows the ‘charger’ as ‘off’ until panel voltage exceeds batt+5. It’s like a switch!

This was at home, and 100% cloud.

[noelex 77]

Originally Posted by daveNZ

Connected new 150W panel and Victron 75/15 Smartsolar mppt reg with all defaults. Yes it waits till PV voltage reaches batt+5V, and shows no solar power during that stage (0Watts). But as soon as it goes over that, the solar power shows as e.g. 7W on a very cloudy sky. Continues to run even though PV voltage hovers around 15V. Brilliant.
My 150W panel has 32 cells.

The start up current (or wattage if you prefer) gives you some idea if the solar controllers start up parameters are correct.

If the controller is starting up at 7w, or 4w (if that is what you are experiencing) is a little late especially with a 150w of solar on a cloudy day with a battery voltage of 12.36v. The ideal start up current (or wattage) is around zero. In practice the amount of lost power with this sort of slightly late start up is not very significant, but when living off solar power on a boat maximising the efficiency is important.

36 cells are the normal for a 12v panel and the slightly late start up for a 32 cell panel is not surprising.