Panels with more bypass diodes

[jsanton]

Interesting!
I specifically asked the tech support for WindyNation about bypass diodes. Here's there's response:
"Yes, all of our panels have diodes. The bypass diode will not assist in power generation, but they will prevent power loss when the panel is not able to generate charge."
They aren't completely clear, but it seems like they don't have bypass diodes but do have a blocking diode.

[s/v Jedi]

Originally Posted by jsanton

Interesting!
I specifically asked the tech support for WindyNation about bypass diodes. Here's there's response:
"Yes, all of our panels have diodes. The bypass diode will not assist in power generation, but they will prevent power loss when the panel is not able to generate charge."
They aren't completely clear, but it seems like they don't have bypass diodes but do have a blocking diode.

What? They say they have bypass diodes but yet you say they don’t?

[noelex 77]

Originally Posted by jsanton

Interesting!
They aren't completely clear, but it seems like they don't have bypass diodes but do have a blocking diode.

Their response is indeed confusing. The quote applies more to blocking diodes than bypass diodes.

The bottom line is there is no reason for solar panel manufacturers to include blocking diodes. It will decrease the published (STC) wattage output of the panel.

Bypass diodes have no effect on the published output and are essential to protect the panel from damage. Any panel without bypass diodes will have a short life.

If you are connecting solar panels in series an additional external bypass diode connected around the whole panel is worth installing.

[FlyingScot]

Originally Posted by s/v Jedi

That is exactly the whole trick of why series is superior: you get extra power from the hugher voltage instead of a higher amperage… and losses are only caused by amperage, not by voltage.

The formula is: Power losses = Amperage squared x resistance.

No voltage in the equation

Did you ever test your setup with individual MPPTs vs series wired MPPTs?

[s/v Jedi]

Originally Posted by FlyingScot

Did you ever test your setup with individual MPPTs vs series wired MPPTs?

No I didn’t because I don’t have enough MPPT’s…. But as long as the panel voltage is high enough, a dedicated controller should at least match the performance of a controller with multiple panels.

[gs41escapade]

I'm just starting to consider a solar install. Great thread and I've learned a lot.

Newbie question -- I contacted renogy to ask if I can keep the solar install connected to the batteries when engine charging. They said 'NO' which seems unworkable in real life. Their stated concern was risk of overcharging the batteries. (I have AGM's at the moment, will face Lithium when these need to be changed out).

The blocking diodes in the MPPT should prevent any damage to the MPPT controller and the panel array, no? What is actually done in the real world?

thanks

[s/v Jedi]

Originally Posted by gs41escapade

I'm just starting to consider a solar install. Great thread and I've learned a lot.

Newbie question -- I contacted renogy to ask if I can keep the solar install connected to the batteries when engine charging. They said 'NO' which seems unworkable in real life. Their stated concern was risk of overcharging the batteries. (I have AGM's at the moment, will face Lithium when these need to be changed out).

The blocking diodes in the MPPT should prevent any damage to the MPPT controller and the panel array, no? What is actually done in the real world?

thanks

Don’t talk to people like that on the phone… they have no clue, probably never been on a boat.

Start by studying diagrams and comparing to your boat installation. Here’s a good start with points that require decisions like Lithium yes/no and how much daily consumption you have and if solar can produce that for you etc.

Edit: the forum attachments don’t work at the moment, I’ll try to upload a diagram later.

[Uncle Bob]

Originally Posted by gs41escapade

I'm just starting to consider a solar install. Great thread and I've learned a lot.

Newbie question -- I contacted renogy to ask if I can keep the solar install connected to the batteries when engine charging. They said 'NO' which seems unworkable in real life. Their stated concern was risk of overcharging the batteries. (I have AGM's at the moment, will face Lithium when these need to be changed out).

The blocking diodes in the MPPT should prevent any damage to the MPPT controller and the panel array, no? What is actually done in the real world?

thanks

I would ask myself what does an alternator do when it sees a fully charged battery, keep on charging regardless or throttle back to virtually no output, similarly what does a solar controller do when it sees the same fully charged battery?
The answer should supply you with sufficient reason to seek information from a knowledgeable source, not necessarily a sales person.

[s/v Jedi]

Let’s see if the upload works now…

[gs41escapade]

I was perhaps too polite in how I stated my question. There is no reason to disconnect the MPPT output connection to the batteries when engine (or shore power) charging. If anyone has a unique or exceptional reason why this would not be true, I would be interested to hear it.

[s/v Jedi]

Originally Posted by gs41escapade

I was perhaps too polite in how I stated my question. There is no reason to disconnect the MPPT output connection to the batteries when engine (or shore power) charging. If anyone has a unique or exceptional reason why this would not be true, I would be interested to hear it.

Nobody with relevant knowledge will because there exists no reason. The problem is that you ask this, which means you don’t have the knowledge required to tackle the project. Furthermore, by asking others with lacking knowledge (the Renogy sales people on the phone), you expose yourself to ignorant people who unfortunately do not hesitate to act like they do have knowledge. Your first point of action is to be able to differentiate between people who are qualified to answer your questions or make recommendations and those who are not.

The diagram I posted above is a reference diagram. It’s not what I have, it includes all required parts/components of a good installation in the way it is properly done. Bring your plans to conform to it and you will have success

[sailingharry]

Jedi, a small disagreement with your reference diagram. On my last boat, which I (re) wired myself, and my new-to-me boat, which came mostly wired the way I like it, I have a "critcial" bus which is before the main battery switch (but on my last boat had a breaker before it, that would allow isolation). It's not ABYC compliant (I think), but it is practical. The "critical" bus includes the bilge pump, the LINK 2000 battery monitor, the "keep alive" on the stereo (so it doesn't forget stations), and a few other odds and ends. The alternator went direct to the battery main fuse, so it could never be disconnected (the new boat has all charge sources to the critical bus, which I don't really like, especially since I no longer have an A/B switch and so the switch is never at risk of mis-operation under way.



Your diagram doesn't allow the battery switch to be turned "off" when away from the boat, without losing the bilge pump functionality. It also doesn't allow solar to keep the batteries topped up if the switch is off. Finally, if the switch is turned off for even a second, the smart shunts lose their battery SOC until the next reset.


Of course, your diagram does allow a very important feature that mine doesn't -- turning the switch OFF actually disconnects the batteries. And at least for me, I turn my switch off about never (I almost never turn off the fridge, so that requires batteries), so it might well make sense

[s/v Jedi]

Originally Posted by sailingharry

Jedi, a small disagreement with your reference diagram. On my last boat, which I (re) wired myself, and my new-to-me boat, which came mostly wired the way I like it, I have a "critcial" bus which is before the main battery switch (but on my last boat had a breaker before it, that would allow isolation). It's not ABYC compliant (I think), but it is practical. The "critical" bus includes the bilge pump, the LINK 2000 battery monitor, the "keep alive" on the stereo (so it doesn't forget stations), and a few other odds and ends. The alternator went direct to the battery main fuse, so it could never be disconnected (the new boat has all charge sources to the critical bus, which I don't really like, especially since I no longer have an A/B switch and so the switch is never at risk of mis-operation under way.

Your diagram doesn't allow the battery switch to be turned "off" when away from the boat, without losing the bilge pump functionality. It also doesn't allow solar to keep the batteries topped up if the switch is off. Finally, if the switch is turned off for even a second, the smart shunts lose their battery SOC until the next reset.

Of course, your diagram does allow a very important feature that mine doesn't -- turning the switch OFF actually disconnects the batteries. And at least for me, I turn my switch off about never (I almost never turn off the fridge, so that requires batteries), so it might well make sense

Hmm… you may disagree with it but yet it’s how it’s supposed to be. Let’s look at your objections:

- 24/7 always on circuits. I have these presented as a bilge pump with an automatic fuse, directly connected to a busbar, bypassing the breaker panel. This is how it’s done in every diagram I have seen. You are not allowed direct connections to the battery.

- Victron BMV’s and I think SmartShunt as well have a setting on what to do after a power reset. Waiting for a 100% charged is one option, remembering soc is another option.

- Leaving the boat, this is your main objection I think. When leaving the boat I disconnect most batteries but leave one house bank battery online and this is the one that powers everything needed. It is exactly the same effect as you connecting direct to the battery, defeating the isolation switch.
To make sure everything else is switched off is simply turning the breakers off or the main switch on the breaker panel.

There’s more: some BMS systems use enough power to drain a battery rapidly. Many sailors need to replace their expensive LFP batteries because of this. In that case it’s much better to leave them online with solar chargers. In order to not keep them fully charged all the time, there are two options to fix that:

1. When you have a Victron BMV, the display unit has an internal relay that can be programmed. You can program it to come on when SOC falls below 30% and to go off when SOC goes above 50%. Now you feed (via fuse) 12V to the relay common contact and the relay Normally Open contact can be connected to all the “remote H” pins of Victron MPPT controllers.

2. When the hardware available isn’t suitable for the first option, you can change the absorption and float voltage settings of the MPPT’s to lower values to accomplish about the same.

I have tested both options successfully.

- alternator and I assume starter connection: this is about the only connection where a fuse isn’t required by ABYC. I do recommend a service switch on the engine that disconnects at minimum DC positive. This creates a safe environment for maintenance or repair work on the engine, as well as a way to disable the engine when leaving the boat.

[sailingharry]

As boats have gotten bigger, more complex, and more power hungry, my father's view that the battery switch is turned off every time you leave the boat is.... kind of ancient history. My current boat is without power right now for about the first time since I bought it 5 years ago (on the hard, no shore power, and very little functional solar), but in general it is never turned off and so my trying to adjust for that is kind of no longer important...


Your comment on BMS draining the battery is something I've come to realize. I'm on a BMS forum (electrodocus), where a few batteries have been toasted by an issue, the bms shuts of everything -- but continues to draw a small but continuous drain. I'm kind of thinking that the BMS should be on the load side of the BMS disconnect for just that reason -- in the exceedingly rare event that the BMS shuts down the battery, it should SHUT IT DOWN. Manual intervention would then be needed to restart things.


I know ABYC allows an unfused starter. I don't think it allows an unfused alternator. In either case, I don't allow it!


When I go to LFP, the LFP disconnect will add a second "battery switch" that will be a total kill switch. I may or may not remove the existing one at that time.