First foray into Solar. Advice needed

[Chris_Robb]

What are the specifications for the panels. Particularly the Vmp and Voc.

See below for specs:

[FONT=Verdana, Arial, sans-serif]Product Key Feature's[/FONT][FONT=Verdana, Arial, sans-serif] [/FONT]

• Residential solar panel power systems applications
• [FONT=Verdana, Arial, sans-serif]Public, commercial and industrial solor panel systems [/FONT]
• [FONT=Verdana, Arial, sans-serif]Suitable for off-grid and grid tie application[/FONT]
• Clear Universal frame and J-type junction box.
• 25 Year Warranty

[TABLE="width: 416"]
[TR]
[TD]Model[/TD]
[TD="align: center"]BP 380J[/TD]
[/TR]
[TR]
[TD]Warranty[/TD]
[TD="align: center"]25 Years[/TD]
[/TR]
[TR]
[TD]Operating Voltage [V][/TD]
[TD="align: center"]12v[/TD]
[/TR]
[TR]
[TD]Peak Power [W][/TD]
[TD="align: center"]80W[/TD]
[/TR]
[TR]
[TD]Tolerance in Output [%][/TD]
[TD="align: center"]+/-5%[/TD]
[/TR]
[TR]
[TD]Max System Voltage[/TD]
[TD="align: center"]600[/TD]
[/TR]
[TR]
[TD]Voltage at Pmax [v][/TD]
[TD="align: center"]17.6[/TD]
[/TR]
[TR]
[TD]Cell Technology[/TD]
[TD="align: center"]Multicrystalline[/TD]
[/TR]
[TR]
[TD]Current at Pmax [A][/TD]
[TD="align: center"]4.6[/TD]
[/TR]
[TR]
[TD]NOCT (DegC)[/TD]
[TD="align: center"]47[/TD]
[/TR]
[TR]
[TD]Open Circuit Voltage [V][/TD]
[TD="align: center"]22.1[/TD]
[/TR]
[TR]
[TD]Short Circuit Current [A][/TD]
[TD="align: center"]4.8[/TD]
[/TR]
[TR]
[TD]Length [mm][/TD]
[TD="align: center"]1209[/TD]
[/TR]
[TR]
[TD]Width [mm][/TD]
[TD="align: center"]537[/TD]
[/TR]
[TR]
[TD]Depth of Jnct Box [mm][/TD]
[TD="align: center"]50[/TD]
[/TR]
[TR]
[TD]Conversion Effiiency[/TD]
[TD="align: center"]13[/TD]
[/TR]
[TR]
[TD]Weight [Kg][/TD]
[TD="align: center"]7.7[/TD]
[/TR]
[TR]
[TD]Number of Cells[/TD]
[TD="align: center"]36[/TD]
[/TR]
[TR]
[TD]Bend Tollerance[/TD]
[TD="align: center"]+/-3%[/TD]
[/TR]
[/TABLE]

 

[Chris_Robb]

Noelex is right with his answer. Ideally the Victron work work better with your two panels connected in series and neither of them in the shade for most of the time. However, if you don't have this luxury, then parallel connection will be better. Your figures seem to be about what you might expect but you will be suffering some degradation in output because the Victron needs to reach its trigger voltage which, from memory, I think is 5V above battery voltage.

There could be an argument that a MPPT controller which has a lower trigger voltage might have been better but contradicting that is the fact the once the Victron does start it apparently has a very effective tracking algorithm so you are probably making up for much of the "lost time".

The only way to be sure you have the best configuration is to switch the wiring from parallel to series and then check the total output over a few 24 hour periods. The Victron dongle will do this but I'm not sure whether you can do it with your equipment. However, you'll probably find that if you happen to be lying with the sun directly on the stern and the boat drifting around to keep this orientation then your series output beats all your records .... but, unfortunately, on the vast majority of normal days, the series output is worse than the parallel.

Richard

Richard, thanks for that interesting answer - and understanding the trigger point of voltage above battery. Battery at AM wake up time is normally around 12.6, so panel voltage needs to be 12.6+5 = 17.5. perhaps I need a change over switch to move from parallel to serial with the flick of a switch! should be possible.

So is it the open circuit voltage ie
[TABLE="class: cms_table, width: 416"]
[TR]
[TD]Open Circuit Voltage [V][/TD]
[TD="align: center"]22.1[/TD]
[/TR]
[/TABLE]
or [TABLE="class: cms_table, width: 416"]
[TR]
[TD]Voltage at Pmax [v][/TD]
[TD="align: center"]17.6 If so it is dangerously near to never starting in the mornings![/TD]
[/TR]
[/TABLE]
I get 8 -9 amps charge from them is this the equivalent in the specs of
[TABLE="class: cms_table, width: 416"]
[TR]
[TD]Current at Pmax [A][/TD]
[TD="align: center"]4.6
[/TD]
[/TR]
[/TABLE]
In which case why am I bothering to move from my STeca! Actually the main reason is when the boat is left and the battery management - long periods over winter. The Blue Solar is meant to be much safer.

Or is it all bullshit - and I should just disconnect all my batteries for the 6 months......

Any advice welcome!

 

[RichardS]

Richard, thanks for that interesting answer - and understanding the trigger point of voltage above battery. Battery at AM wake up time is normally around 12.6, so panel voltage needs to be 12.6+5 = 17.5. perhaps I need a change over switch to move from parallel to serial with the flick of a switch! should be possible.

So is it the open circuit voltage ie
[TABLE="class: cms_table, width: 416"]
[TR]
[TD]Open Circuit Voltage [V][/TD]
[TD="align: center"]22.1[/TD]
[/TR]
[/TABLE]
or [TABLE="class: cms_table, width: 416"]
[TR]
[TD]Voltage at Pmax [v][/TD]
[TD="align: center"]17.6 If so it is dangerously near to never starting in the mornings![/TD]
[/TR]
[/TABLE]
I get 8 -9 amps charge from them is this the equivalent in the specs of
[TABLE="class: cms_table, width: 416"]
[TR]
[TD]Current at Pmax [A][/TD]
[TD="align: center"]4.6
[/TD]
[/TR]
[/TABLE]
In which case why am I bothering to move from my STeca! Actually the main reason is when the boat is left and the battery management - long periods over winter. The Blue Solar is meant to be much safer.

Or is it all bullshit - and I should just disconnect all my batteries for the 6 months......

Any advice welcome!

As I understand it, the voltage at Pmax is the voltage at which the panel produces its maximum power so its a theoretical figure although one which the MPPT controller will try to mimic as it tries to track the same maximum power point. Your panel will produce more than that once the sun gets on it and, as you say, once it hits around 17V (assuming your battery is not fully charged before it even starts) it will start tracking and, if I recall correctly, continue to track until the panel voltage above battery level is 1 or 2 volts or something like that.

I've never heard of anyone having a parallel / series switch although it must be possible although one panel is perhaps likely to be in most shade when the sun is low in the morning so even in series I guess it might not be providing that much voltage. However, you must be right that it's still got to be better than the two panels in parallel voltage-wise although I guess that the current would be low so probably not much charging going on anyway.

Would you have space to fit another, perhaps smaller, panel alongside the existing ones and connect those 2 in series? In effect, that's what I have although mine are all the same size which is the ideal situation.

I know some people on here do leave their batteries disconnected for the winter but I have always kept mine connected to solar through a controller.

Richard

 

[noelex]

Hi Criss. It it the Voc that is the important number (not Vmp) that will determine if the Victron will start in the morning.

The Victron periodically samples the solar panel voltage. First thing in the morning the panels are not connected to the battery, or producing any power, so the solar panel voltage is Voc or very close to Voc.

At this stage the Voc of panel will not be the same as the Voc listed in the specifications. The Voc in the specifications is measured in very bright conditions and with a relatively cool panel temperature. It is also measured on a panel with no shadow at all and where the panel is spotless clean and brand new. So in real life the Voc of the panel first thing in the morning as he sun rises will be considerably less than the 22.1v listed.

The important question is will the Voc first thing in the morning be at least 5v over the battery voltage.

A specified Voc of 22.1v is not as high as some 36 cell panels but is considerably better than the 20v that you were remembering. The extra 2.1v makes a big difference in determining if the Victron will start. I think it is going to be quite rare that Victron will not start at the correct time. It is not the optimum configuration, but I think in practice so little will be lost that I would probably would not bother trialling any changes.

However, this is assuming there are no other charge sources overnight. This means the maximum battery voltage in the morning will be about 12.6v and a more typical battery voltage might be around 12.4v. So the Voc of the panels in the morning in the worst case would need to be 12.6 +5= 17.6v (and more typically 17.4v) before the Victron will start. This will normally be fine.

If you had another charge source like wind that was producing power overnight. The battery voltage in the morning could be 14v+. If the battery voltage was this high the Victron would not start until the solar panel voltage was 19v + . So in a hot climate the solar would never start. With a battery voltage of 14v+ the batteries might be fully charged, but not necessary so.

So if you have wind I would switch the panels to series connection, or at least give this a trial (even though this not ideal). If you don't have wind (or hydro or a fuel cell) the system should work fine in parallel as you have it at the moment.

If you check when the system starts in the morning that would be helpful.

 

[PaulRainbow]

Hi Criss. It it the Voc that is the important number (not Vmp) that will determine if the Victron will start in the morning.

The Victron periodically samples the solar panel voltage. First thing in the morning the panels are not connected to the battery, or producing any power, so the solar panel voltage is Voc or very close to Voc.

At this stage the Voc of panel will not be the same as the Voc listed in the specifications. The Voc in the specifications is measured in very bright conditions and with a relatively cool panel temperature. It is also measured on a panel with no shadow at all and where the panel is spotless clean and brand new. So in real life the Voc of the panel first thing in the morning as he sun rises will be considerably less than the 22.1v listed.

The important question is will the Voc first thing in the morning be at least 5v over the battery voltage.

A specified Voc of 22.1v is not as high as some 36 cell panels but is considerably better than the 20v that you were remembering. The extra 2.1v makes a big difference in determining if the Victron will start. I think it is going to be quite rare that Victron will not start at the correct time. It is not the optimum configuration, but I think in practice so little will be lost that I would probably would not bother trialling any changes.

However, this is assuming there are no other charge sources overnight. This means the maximum battery voltage in the morning will be about 12.6v and a more typical battery voltage might be around 12.4v. So the Voc of the panels in the morning in the worst case would need to be 12.6 +5= 17.6v (and more typically 17.4v) before the Victron will start. This will normally be fine.

If you had another charge source like wind that was producing power overnight. The battery voltage in the morning could be 14v+. If the battery voltage was this high the Victron would not start until the solar panel voltage was 19v + . So in a hot climate the solar would never start. With a battery voltage of 14v+ the batteries might be fully charged, but not necessary so.

So if you have wind I would switch the panels to series connection, or at least give this a trial (even though this not ideal). If you don't have wind (or hydro or a fuel cell) the system should work fine in parallel as you have it at the moment.

If you check when the system starts in the morning that would be helpful.

If using a Victron controller i believe it is important to have either the Bluetooth device or the USB cable, in which case it's easy to check what time the controller starts in the morning.

 

[noelex]

If using a Victron controller i believe it is important to have either the Bluetooth device or the USB cable, in which case it's easy to check what time the controller starts in the morning.

The Victron Bluetooth reporting is excellent. Using this you can see how the solar panel voltage rises in the morning. Ideally the controller should turn on just as the power going into the battery is positive (ie greater than the self consumption of the controller).

BTW, the latest controllers have inbuilt bluetooth so don't need the seperate bluetooth dongle.

 

[Chris_Robb]

If using a Victron controller i believe it is important to have either the Bluetooth device or the USB cable, in which case it's easy to check what time the controller starts in the morning.

I have the app to connect my Android phone to it by bluetooth. Cant of course check how this works in advance until the victron is fitted.

 

[Chris_Robb]

Thanks Guys - I shall proceed as planned and keep the parallel connections. It is encouraging to know that the App on my phone will give me so much information. I will check that all is normal before removing the STeka and connect up the new Victron. Worth RTFM I think:encouragement:

 

[GHA]

If you check when the system starts in the morning that would be helpful.

This is for similar setup - 200W solar on the guard rails, 2 x T105. Victron 75-10. 22nd sept with sunrise - 06.20, set - 18.28. Looks like it starts waking up maybe half hour after sunrise.

 

[Chris_Robb]

This is for similar setup - 200W solar on the guard rails, 2 x T105. Victron 75-10. 22nd sept with sunrise - 06.20, set - 18.28. Looks like it starts waking up maybe half hour after sunrise.

Thats really helpful. Does it also give a similar chart for Amps produced etc?

 

[GHA]

Thats really helpful. Does it also give a similar chart for Amps produced etc?

That's actually from a raspberry pi saving voltage, the data from the victron is also very good. I messed up a bit by ordering a 75-10 instead of a 75-15 but rarely with the 2 panels does the current get up to 10a anyway.

 

[noelex]

Thanks for posting the graph. It is amazing the information that is available from instruments these days, especially with a little ingenuity and raspberry pi.

I think the controller probably woke up at point one, which is the first time the voltage starts to rise. If this is the case it looks like the controller woke up an appropriate time. The voltage only rises very slowly and slightly after point one (ignoring the regular spikes which I presume is caused by the fridge kicking in).

Theres a chance that point one was just a slight glitch and the controller woke up at point two. The very rapid rise in voltage after this point means if this was the case I think the controller woke a little late. The rapid rise in voltage indicates there was a reasonable amount of power at start up which suggests if the controller had woken up earlier there would still have been some positive contribution from the panels.

The Victron app will show the status of the controller so in the morning it will switch from "sleeping" to "bulk" . The current produced just after this switchover indicates if the controller has woken up at the correct time. If the controller is immediately producing significant current it should have woken up earlier, assuming conditions have otherwise been steady. If the current produced is not possitive at this point the self consumption of the tracking circuitry is greater than the power produced and the controller has woken up too early. The more advanced controllers have adjustable start up parameters so this can be fine tuned. With the Victron range the start up parametrs are fixed at +5v which means the start up can sometimes be a little slow with lower voltage panels.

1/2 hour after sunrise could be good or poor depending on the location amount of cloud etc.

 

[GrahamM376]

The Victron bluetooth app is good, but sometimes I'm scratching my head interpreting results and wondering whether to series instead of parallel panels.
Obviously recent weather + sun low on beam + rain some days aren't the best for consistency. Bar graph (Smartsolar 75/15) show wildly varying charges e.g. one day 100% (10h 43min) bulk with no abs or float, Max volts 14.4, Min volts 12.32. 510WH. Another day 41% bulk (4hr 21 min), 13% abs and 46% float. Max volts 14.89, Min volts 12.39, 370 WH.

 

[Chris_Robb]

The Victron bluetooth app is good, but sometimes I'm scratching my head interpreting results and wondering whether to series instead of parallel panels.
Obviously recent weather + sun low on beam + rain some days aren't the best for consistency. Bar graph (Smartsolar 75/15) show wildly varying charges e.g. one day 100% (10h 43min) bulk with no abs or float, Max volts 14.4, Min volts 12.32. 510WH. Another day 41% bulk (4hr 21 min), 13% abs and 46% float. Max volts 14.89, Min volts 12.39, 370 WH.

Looks like one could get obsessed with this quite easily!

All a great help. Thanks

 

[GrahamM376]

Looks like one could get obsessed with this quite easily!
All a great help. Thanks

Obvious from many posts on the forum that many have in depth knowledge and like tweaking things whereas I just prefer something "plug and play". The main advantage to me of the Victron is that it allows the user to set charging voltages to suit the batteries, in my case Trojans, whereas the cheap Chinese one I had before was set and undercharging.

 

[noelex]

This looks fine Graham. It looks like your absorption voltage is around 14.8. On day one the panels never raised the battery voltage to this level (the max was 14.4V) so the controller stayed in bulk all day as should do.

The second day the controller reached the bulk voltage after 4hr so switched to absorption and then to float. The total power output was less because the controller was regulating which is basically throwing away power to avoid overcharging the batteries.

 

[GrahamM376]

This looks fine Graham. It looks like your absorption voltage is around 14.8. On day one the panels never raised the battery voltage to this level (the max was 14.4V) so the controller stayed in bulk all day as should do.

The second day the controller reached the bulk voltage after 4hr so switched to absorption and then to float. The total power output was less because the controller was regulating which is basically throwing away power to avoid overcharging the batteries.

OK so far thanks but, what voltage is bulk? Whereas Absorption, Float & Equalisation voltages can be user set (14.82v, 13.5v & 16.2v in my case) there's nothing there to indicate what Bulk is.

 

[PaulRainbow]

I have the app to connect my Android phone to it by bluetooth. Cant of course check how this works in advance until the victron is fitted.

May i suggest that you use the app' to manually select your battery voltage and set it to manual. I know a few people have found the Victron set itself to 24v on 12v systems.

 

[Chris_Robb]

May i suggest that you use the app' to manually select your battery voltage and set it to manual. I know a few people have found the Victron set itself to 24v on 12v systems.

Yes I noticed that the instructions appear to expect it not to work!

 

[noelex]

OK so far thanks but, what voltage is bulk? Whereas Absorption, Float & Equalisation voltages can be user set (14.82v, 13.5v & 16.2v in my case) there's nothing there to indicate what Bulk is.

On most modern controllers, including the Victron, the bulk and absorption voltages are identical.

First thing in the morning the solar regulator will start in the Bulk phase. In this phase the total power from the solar panels will be allowed to flow into the battery and the voltage will gradually rise until the bulk voltage is reached. For the Victron this is the same as the absorption voltage, which in your case is 14.82v.

Once the battery voltage has hit 14.82v, the bulk phase is over and the absorption phase begins. In this phase the voltage no longer rises. The controller attempts to keep the battery voltage at 14.82v. This will mean not using some power from the solar panels. The voltage is kept at 14.82v for the absorption time, which is typically a couple of hours. Only the time at 14.82v is counted. If the voltage drops below 14.82v (because of high load or cloud) the timer is paused.

Once the batteries have been kept at 14.82v for the total absorption time, the float phase begins.

During the float phase the voltage is kept at 13.5v.