Solar Controller Size

[charlie22824]

I think I have figured out what size solar charger I need but, I just want to make sure first before I buy it.

I have 2 200watt Renogy solar panels connected in parallel
The Open Circuit Voltage is 27v (Voc)
The Short-Circuit Current is 9.66A (Isc)
The Optimum Operating Current is 8.85a (Imp)
Batteries are 12V Lithium
Building a Sprinter Van for Van life (USA)
Im figuring the Minimum solar charger would be a MPPT 30amp.
If I decided to add another 200watt panel would a 40amp MPPT be find.

Thanks everyone

 

[sunshine_eggo]

Can't answer your question without knowing the battery voltage.

 

[John Frum]

Also mobile vs stationary.

 

[charlie22824]

Can't answer your question without knowing the battery voltage.

12v lithium. thank you for that

 

[charlie22824]

Also mobile vs stationary.

mobile. I updated my first post thank you for that

 

[sunshine_eggo]

400W/14.4V = 28A controller

 

[Rocketman]

You have the right idea.

I had two 210w panels on a Victron 100/30 mppt - that’s the right size. I just finished installing another panel on that array - so now I am “overpanled”. Yes at max I will still just get 30amps - but the extra solar will boost my production when things are not perfect - and they never are in a MotorHome.

If you do decided to add the extra panel - you don’t need to change out the charge controller.

 

[charlie22824]

400W/14.4V = 28A controller

The 30 will work okay? or is it to close to the solar controllers limit should I upgrade to a 40 instead?

 

[John Frum]

With 2 panels you can do 2s or 2p.
With 3 panels you can do 3s or 3p.
Since the application is mobile you probably want to go parallel to mitigate shading.
Since the panels will be flat their efficiency will be approximately 50 to 60 percent so its reasonable to over panel.

 

[brb58]

The 30 will work okay? or is it to close to the solar controllers limit should I upgrade to a 40 instead?

Easily. If you are flat mounting these panels, you will never see more than 80% anyway and it's fine to slightly overpanel.

If the panels actually have bypass diodes(that work), you can put in series

 

[charlie22824]

Easily. If you are flat mounting these panels, you will never see more than 80% anyway and it's fine to slightly overpanel.

If the panels actually have bypass diodes(that work), you can put in series

okay thank you. do you think it would be possible to add another 200watt later on with that 30? I'm assuming that's what you mean about over paneling

 

[charlie22824]

You have the right idea.

I had two 210w panels on a Victron 100/30 mppt - that’s the right size. I just finished installing another panel on that array - so now I am “overpanled”. Yes at max I will still just get 30amps - but the extra solar will boost my production when things are not perfect - and they never are in a MotorHome.

If you do decided to add the extra panel - you don’t need to change out the charge controller.

ok thank you!

 

[charlie22824]

With 2 panels you can do 2s or 2p.
With 3 panels you can do 3s or 3p.
Since the application is mobile you probably want to go parallel to mitigate shading.
Since the panels will be flat their efficiency will be approximately 50 to 60 percent so its reasonable to over panel.

thank you

 

[charlie22824]

400W/14.4V = 28A controller

thank you

 

[sunshine_eggo]

The 30 will work okay? or is it to close to the solar controllers limit should I upgrade to a 40 instead?

30A is more than adequate. It's more common to OVER panel a controller (more array power than the controller can deliver). Provided the PV array Isc does not exceed the PV current input limit (35A, in the datasheet), and the array Voc does not exceed the 100V limit, you can safely put more array on it than the controller can output.

Given your panels, you could put a 3S3P 1800W array on a Victron 100/300 MPPT. Of course, it will never output more than 30A.

If you want to add more in the future a 100/50 may be more practical.

 

[brb58]

okay thank you. do you think it would be possible to add another 200watt later on with that 30? I'm assuming that's what you mean about over paneling

As long as you don't go over the input current spec or the input voltage spec you can. You might be pretty close if you put them in parallel on the rare occasion with perfect sun angle you happen to hit 9.66A ISC on all 3. Hight doubtful though.

Which solar controller?

 

[charlie22824]

30A is more than adequate. It's more common to OVER panel a controller (more array power than the controller can deliver). Provided the PV array Isc does not exceed the PV current input limit (35A, in the datasheet), and the array Voc does not exceed the 100V limit, you can safely put more array on it than the controller can output.

Given your panels, you could put a 3S3P 1800W array on a Victron 100/300 MPPT. Of course, it will never output more than 30A.

If you want to add more in the future a 100/50 may be more practical.

thank you

 

[charlie22824]

As long as you don't go over the input current spec or the input voltage spec you can. You might be pretty close if you put them in parallel on the rare occasion with perfect sun angle you happen to hit 9.66A ISC on all 3. Hight doubtful though.

Which solar controller?

haven't decided yet on a victron 30a or 40a or a renogy 30a or 40a.

 

[sunshine_eggo]

haven't decided yet on a victron 30a or 40a or a renogy 30a or 40a.

No 40A. 100/30, 100/50 and 150/45.

 

[charlie22824]

No 40A. 100/30, 100/50 and 150/45.

ohh ok thank you! well ill probably stick to a 30 100/50 or a 150/45 would be overkill!