Victron BlueSolar charge controller

[noelex 77]

Originally Posted by BigAl.NZ

Ok, but why? What happens if you have one controller, 4 panels and one panel goes in the shade?

One controller servicing several panels connected in parallel is a good solution. If one panel is completely shaded it produces little power, and with this sort of set up the output of the other three panels will not be affected.

The problem with the set up is when one panel is partialły shaded with perhaps some diffuse shade, so its output is diminished, but it is still capable of producing some useful power. In this case the Vmp of the panel in the shade is likely to be different to the Vmp of the unshaded panels. With only one controller all the panels need to be the same voltage so this cannot happen.

So the controller can use the Vmp of the panels in full sun, in which case the output of these panels will be as good as can be and therefore unaffected, but the voltage of the panel in partial shade will be wrong. As the shaded panel Vmp will be lower using the higher voltage, this will mean the shaded panel will have almost no output. The other option is for the controller to pick a compromise voltage. This will result in a sub optimal output for all panels, but the total output may be highest. The controller makes these decisions automatically. The message is one controller can only operate at one Vmp and if the panels are in different conditions (say one in full sun and one with shade) the Vmp of the panels will be different so a compromise must be chosen.

The alternative is to use one controller for each panel. The Vmp of each panel can be completely different and the controller will adjust itself to this voltage. If one panel is in partial shade and its Vmp is low, the controller for that panel can run at this voltage to maximise the output. The other panels in full sun can be run at their optimimum Vmp.

However, there are drawbacks to multiple controllers. The major one is that it takes a reasonable amount of power to operate the tracking and voltage conversion circuitry. With three controllers this self consumption can be significantly higher. The controller manufacturers are bit sneaky here. They generally quote the sleeping self consumption and do not list the self consumption when the unit is operating normally. With the larger units I have measured self consumption of 7-8w so three of these units would consume a reasonable amount of power, especially in low light.

The second drawback of multiple controllers is the potentially reduced sophistication of circuitry. This affects the tracking performance and the efficiency of the voltage conversion. Small, less expensive controllers are often not as good as larger, more expensive controllers with respect to these performance parameters. However, this also has some benefits in reducing self consumption of the smaller controllers. So three units will not have 3x the self consumption of one larger unit.

Overall, I think multiple controllers are likely to offer the best solution, but this is dependent on the equipment and particular installation. Parallel connection to a single controller is still a very good option, especially when the panels are likely to experience similar conditions.

[john61ct]

Victron 75/15 at under $100.

Choose high-voltage panels 200-300w to get max production from each.

Can actually cheaper than a smaller number of higher capacity models.

[socaldmax]

Originally Posted by BigAl.NZ

Ok, but why? What happens if you have one controller, 4 panels and one panel goes in the shade?

It's very simple, really. The MPPT controller is constantly seeking that voltage where the panel produces max. power, let's say it's sunny and 3 panels are in full sun and producing MP at 37v. The 4th panel is pretty heavily shaded and only producing 20v. What does the MPPT controller do? Try and average 20v with 37v? That would reduce the power from the 3 good panels. Ignore the lower powered panel? Then you're losing the partial power it could produce. Since there can only be one voltage on the PV line, solar panels in partial shade cannot be harvested at MP.

With one MPPT controller per panel, each controller can easily track the MP voltage of it's single panel under all conditions and guarantee MP under all conditions.

Think of it like being married. All wives think it's your job to make them happy. If you had 4 wives and one wanted to go shoe shopping, one wanted to go to the movies, one wanted to go for a picnic and the 4th wanted to go home and tear up the bedroom with you. How in the world are you going to make all of them happy at the same time? You can't. It's impossible.

That's why it's better to have only one wife and one MPPT controller per panel. Sure when the sun is shining on everyone, they might all be happy for the moment. But how long do those moments last? From my experience, a few minutes at a time, at most. YMMV.

[foggysail]

My experience using two parallel solar banks in series along with a Victron 150-70 controller has found that shading's impact on my controller's output was not as expected. Yes, when one bank is/was partially shaded by my radar arch the charging current did diminish but NOT to 1/2 the current others claim should happen. I mounted two panels on my forward hardtop and the other two onto my rear hardtop which is about three feet lower than the forward hardtop. The panels are Canadian rated at 295 watts, 30 Vmp each.

I have not expended much effort to analyze all the conditions that resulted in the unexpected higher performance although I believe there are two major factors. The first relates to the panel diodes, the second is that shading impact is overrated. Sure, if one places a towel over a panel there becomes a complete illumance blockage on the panel's covered area. But that is not real life shading. There is always illumance happening, even during a clouded sky.

EDIT: This season has just about ended for me. Next season I will pay attention to the panel output voltage to the controller as measured with my Victron battery monitor. That should be a better indicator of partial shading on my boat.

[john61ct]

It's serial connections where you see huge effects.

Diodes do mitigate, but just a bit.

Just a twig or bird splat can reduce bigly.

[foggysail]

Yes John, bird splats can result in complete illumance blockage to diodes unlike shading from far way objects. My situation described above employes parallel panels connected in series.

[travellerw]

Originally Posted by foggysail

Yes John, bird splats can result in complete illumance blockage to diodes unlike shading from far way objects. My situation described above employes parallel panels connected in series.

We have had the same results as you.

We run 3 strings of panels, 1 string of 4 80W panels, 1 string of 2 150W panels and one string of 2 100W panels. Each string is connected in series to thier own MPPT controller.

We have not seen anywhere near the shading issues that other people talk about. There are times where our mast will cast a shadow across a panel. We do loose some, but not anything like we were led to believe. We might drop to 220-230W from our full output of 300W.

For our boat, series has proven to work very well.

[Mais78]

Hi guys, can you please help with m configuration.
Yard (Pogo), proposed a flying Solbian SP 104W with BlueSolar 75/10 and BMV 702. battery is lithium.

1) Instead of the Bluesolar 75/10, I would like to buy either the Smart Solar 75/15 or the Genasun GV-10. Any recommendation?
Is it still the case that the Genasun produces 10% more? With the Victron I can add a second panel in the future (supports up to 220W vs 140W of Genasun)?
This test was done by OceanPlanet who writes in this forum.
http://www.solbian.eu/img/cms/PDF/4-...%20Genasun.pdf

2) Battery Monitor: instead of the BMV 702, I'd rather take either the BMV 712 Smart or the Pico https://simarine.net/product/pico-standard-package/
Any view also here? Pico seems cool but maybe you cannot integrate it with the controller?

Thanks!

[Pete7]

I have no experience with the Gensun controllers but have with the Victron. I note that the report you linked to from Ocean Planet is now 5 years old. During that time Victron have produced their smart range of MPPTs and then rolled out a series of modifications to the software that has given us the customers, some very nice additions and huge control over the charging profiles etc.

Gensun may have done something similar I just don't know. However, I have a 100/20 driving the main panel, a 75/15 our portable suitcase panel and I have just sold to a friend a 75/10 which I no longer have a use for. Wishing to keep the friendship I wouldn't have sold it to him if there was any doubt about its performance.

The ability to upgrade later on with extra panels will be useful, no one ever says they have enough.

Pete

[Pete7]

The Pico looks nice, but you are paying a lot for the battery monitor and tank gauges. We use a garden cane to dip the fuel tank and until recently used the angle of the mast to judge how much the boat leaned therefore how much water is in the tank on the starboard side.

There is a cheaper battery only Pico:

https://simarine.net/product/pico-battery-monitor/

Perhaps compare this to the Victron BMV range.

Pete