Solar on van and portable solar question

[DavidStratton]

I would like to run two separate solar "rigs" separately to the same solar controller. I currently have a 290 watt panel mounted permanently to the to of my van. I have also put together two 100 watt panels in series to use as portable solar. I do not see the need to use both to charge the batteries simultaneously. So what I would like to do is be able to connect positive and negative wires from each panel to a switch that will let me chose which panel to be working and have one set of positive and negative wires going from the switch to the controller. Sounds simple enough but I don't know if there exists such a switch.

Reason for the either/or preference is that the two 100 watt panels when pointed more or less in the direction of the sun actually deliver more voltage than the single 290 watt panel flat on the roof. Either setup produces power alone that will meet our need. If I can park in shade and have the two 100 watt panels in the sun then that works for me.

Any thoughts on how to wire this up?

 

[SamDeleted]

Dual pole , DC rated transfer switch

https://www.amazon.co.uk/Heschen-Universal-Selector-Changeover-Terminals/dp/B097T3DXV8/ref=pd_aw_vtp_h_pd_aw_vtp_h_sccl_1/257-1591549-1454461?pd_rd_w=V4e1s&content-id=amzn1.sym.158d9d57-b9e0-46b1-a1e0-412c040df4f4&pf_rd_p=158d9d57-b9e0-46b1-a1e0-412c040df4f4&pf_rd_r=JD82XXRDHE1C16Q7ZVST&pd_rd_wg=Qg9MC&pd_rd_r=cff579be-9ba4-4030-a6c7-285181c1df39&pd_rd_i=B097T3DXV8&psc=1

 

[SamDeleted]

Do you have the specs of both the 290w panel , and the two 100w panels

It is possible that you could use all of them at once in one mppt , if the specs line up

 

[SamDeleted]

Your other option is to get a second separate MPPT for the outdoor panels

 

[BenQ]

You could make a combiner box with circuit breakers and just switch off the breaker for the panels you don’t want to use.

Something like what this guy makes at 16minutes on this video should work.

 

[0truck0]

I would not. Get another MPPT controller and run that into your one battery at the same time as the other one charges it. Things break, and this way you have two complete solar working set-ups. The charger/controller is not the expensive part, $50 or less on ebay for you small wattage.
I originally had two 200 watt set-ups charging one battery, two identical set-ups. I since added a 2nd battery so have two identical systems in one trailer.

 

[DavidStratton]

Do you have the specs of both the 290w panel , and the two 100w panels

It is possible that you could use all of them at once in one mppt , if the specs line up

Sam, when I meter the voltage output of the 290 panel I get about 34V. When I do the same for the two 100s in series I get 40V or better. My concern about using two separate SCCs (I have available my original EP Ever) is my worry about differing charge parameters of the two. I think the change over switch letting me chose which panel output goes to the controller feels safer. Current SCC is a Kisae DMT1250 connected to the roof 290 watt panel. Any further thoughts?

 

[BenQ]

Sam, when I meter the voltage output of the 290 panel I get about 34V. When I do the same for the two 100s in series I get 40V or better. My concern about using two separate SCCs (I have available my original EP Ever) is my worry about differing charge parameters of the two. I think the change over switch letting me chose which panel output goes to the controller feels safer. Current SCC is a Kisae DMT1250 connected to the roof 290 watt panel. Any further thoughts?

Depending on which EPEver you have you should be able to create a user charging profile to match the Kisae charge controller. The. You won’t need to buy extra parts and as 0truck0 said, redundancy isn’t a bad idea.

 

[SamDeleted]

Sam, when I meter the voltage output of the 290 panel I get about 34V. When I do the same for the two 100s in series I get 40V or better. My concern about using two separate SCCs (I have available my original EP Ever) is my worry about differing charge parameters of the two. I think the change over switch letting me chose which panel output goes to the controller feels safer. Current SCC is a Kisae DMT1250 connected to the roof 290 watt panel. Any further thoughts?

Try not to confuse voltage with total energy production


Watts are what really matters

V x A = watts

So for instance, I have 245w panels that run at 60v

. I also have much bigger 430w panels that run at only 30v

 

[SamDeleted]

Now its more than possible your two 100ws in a good spot facing the sun are making more than one 290w panel in a less than optimal position flat on a roof

It's just voltages does not show that

 

[littleharbor2]

If your 290 watt panel is a 72 cell model you can parallel the 2 series wired panels with it into your existing controller. The voltage you gave for it may have been the under load voltage while the voltage you gave for the 100 watt panels sounds like open circuit voltage. It's all about the cell count. 2 36 cell 12 volt panels vs. 1 72 cell large panel. If the 290 is a 60 cell version then you have a mismatch.

 

[fratermus]

My concern about using two separate SCCs (I have available my original EP Ever) is my worry about differing charge parameters of the two.

It's a non-issue, assuming

1. both configs are appropriate for the battery bank
2. the combined charging current isn't more than the bank can handle

 

[SamDeleted]

It's a non-issue, assuming

1. both configs are appropriate for the battery bank
2. the combined charging current isn't more than the bank can handle

Yes it's total acceptable, a done thing


They do not have to have exactly the same settings

 

[DavidStratton]

Roof panel is a Solar World SW290 and the short circuit current is 9.97A. It is a 60 cell panel. Open circuit voltage is 39.9V. The two HQST 100D-SS panels are hinged together and wired in series. Spec sheet shows short circuit current 5.34 and open voltage at 24.3V and they are 36 cell. My understanding is that wired in series I have doubled the voltage but kept the amps at 5.34. I did it that way in order to use a 12awg cord to run fro the panels to the van where the SCC will be right next to the batteries. It appears to me from littleharbor2 that I have a mismatch of panels which if I understand littleharbor2 I cannot wire together to go into the Kisae SCC and will want to use the second controller an EPEver 3210A. I also think you are telling me that if I set the user settings on the EPEver to the lithium parameters I can have both SCC feeding the batteries simultaneously with no problems. Have I got that correct this time? Thanks to all for your help and patience.

 

[SamDeleted]

Or this could be an option:

When miss matched solar arrays are wired in parallel, the amps add together, the voltage is set by the lowest

290w
9.97 amps
39.9v open

200w folding array (2x100 in series)
5.34 amps
48.6v open


... these two wired in parallel to the same mppt you would make:

15.31 amps
39.9v open

So you'd get the full output from the 290w, but you are cutting the top 10v off the 200w folding array, costing you roughly 20% of it's output - around 40w


Giving you rough total of 450w all together

Using Mismatched Solar Panel Sizes in the Same Array

This blog post will teach you how using mixed and mismatched sizes of solar panels in the same array will affect the output of the entire array.

explorist.life

 

[SamDeleted]

So your cutting the top 10v off the 200w folding array, costing you roughly 20% of it's output - around 40w


Giving you rough total of 450w all together

For me , I don't think it's worth it to buy and install a whole new charge controller trying to chase just 40 extra watts

I'd parallel the 200w folding array in to your current mppt , possiblity with a small Anderson connector for easy disconnect

 

[BenQ]

Roof panel is a Solar World SW290 and the short circuit current is 9.97A. It is a 60 cell panel. Open circuit voltage is 39.9V. The two HQST 100D-SS panels are hinged together and wired in series. Spec sheet shows short circuit current 5.34 and open voltage at 24.3V and they are 36 cell. My understanding is that wired in series I have doubled the voltage but kept the amps at 5.34. I did it that way in order to use a 12awg cord to run fro the panels to the van where the SCC will be right next to the batteries. It appears to me from littleharbor2 that I have a mismatch of panels which if I understand littleharbor2 I cannot wire together to go into the Kisae SCC and will want to use the second controller an EPEver 3210A. I also think you are telling me that if I set the user settings on the EPEver to the lithium parameters I can have both SCC feeding the batteries simultaneously with no problems. Have I got that correct this time? Thanks to all for your help and patience.

You are correct sir!

 

[BenQ]

For me , I don't think it's worth it to buy and install a whole new charge controller trying to chase just 40 extra watts

I'd parallel the 200w folding array in to your current mppt , possiblity with a small Anderson connector for easy disconnect

He already has the extra charge controller.

 

[SamDeleted]

He already has the extra charge controller.

Yes good spot