Sizing Charge controller for 305w solar panels

GoingDark90

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Nov 12, 2021
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I have 15 Sunpower solar panels. I am looking for assistance in determining the wiring style ( series/parallel/ or mixed) and a Charge controller unit that would work with these panels. I want to create a Solar RV/Camper Plugin station using a 30amp 110 Plug.
Solar panel Specs
Brand SunPower
Peak Power 305 W
voltage 54.7 V
Current 5.58 A
Open circuit volt 64.2 V
short circuit current- 5.96 A
max series fuse 20 A

Model= SPR-305EL-WHT-D

I don't know what charge controller would be able to handle these pannels. Most panels I see are 100watts.

Any help appriciated.

Tom
 

sunshine_eggo

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You're not looking around much. On this forum 100W panels aren't often used.

Depends on your battery voltage.

15 * 305W = 4575W

4575W/(battery voltage)= charge current needed from the MPPT charge controller(s).

15 panels kinda shoots you in the foot on almost all controllers. You're limited to parallel.

15P

Most would accommodate 2S, but then you have an odd panel.
 

GoingDark90

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Nov 12, 2021
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I dont need to use them all at once but something that could run 2 Parked Campers offsite.
I have 8 marine deep cycle batterys 12v batteries.

Any recommendation on the MPPT charge controller that could manage the loads. I have a lead on one of these
for a 2nd hand price-

so if that would work. ill just get it. I don't want to waste money on stuff that wont work long term.

Thank you
Tom
 

rmaddy

Full-time Solar-powered Trailer Life
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15 305W panels means A LOT of charge current. Even with a 48V system you are looking at about 90A. You could do it all using something like the Victron 250/85 with the panels in 3S5P. If you got one more panel you could do 4S4P. But again, this would only work with a 48V system. You might be able to do 2S7P or 2S8P with a 150/85.

With a 24V or 12V system you can't use just one charge controller because there would be way too much current involved.

Again, with one more panel you have a lot more options. With 16 panels and a 24V system you could use two charge controllers, each with 8 panels. You would need two controllers such as the Victron 150/100 or maybe the 150/85. Each controller would have 8 panels in 2S4P.

Don't even consider 12V with that many panels. You would need 4 controllers.
 

rmaddy

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The controller you link can only handle 100V input. So you could only put the panels in parallel. And it's for a 24V battery with a max of 60A output current. 24V at 60A is 1440W. You might be able to put 5 panels in parallel with that controller, maybe only 4.
 

chrisski

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Aug 14, 2020
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I recommend figuring out your power requirements.

If the requirements were large to approaching what they can produce:

-15 panels in a 3S5P Southerly configuration with 200 volt or higher SCCs (expensive). 5S3P would work also, but that would need a 300 volt or 350 volt controller (much more expensive).

If the requirement is small and not approaching the panels would produce:

- Panels in the south to produce the most power but east and west facing panels to get more on-demand power when the sun rises and sets. THe southerly Array could have 9 panels 3S3P with a southerly direction and a 200 volt SCC, and the East and West would both receive one 3S configuration with a 200 volt controller.

The power requirement would guide me and the end product would be much different, but that would be my first thoughts. To some extent max amperage to the batteries would guide this also, and this is more of a factor with FLA and much less with Lithium.
 

GoingDark90

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Nov 12, 2021
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Appreciate the assistance, going to get each trailers load ratings. May be best to run 2 separate systems then if I’m reading some of these replying correct. Independent per trailer loads. I’m 100% newb when it comes to electricity. Much appreciated
 

MichaelK

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Mar 21, 2020
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What no-one has mentioned yet is using a string calculator. I like this one.
You plug your panel values into the left panel, and see what the resulting power levels are like on the right panel.

Looking at three panels in series, the Voc around freezing is so high that only a controller that can handle 250V is recommended. What are your winter lows like? That temperature can be plugged into the calculator.
1636818271963.png

Here I re-wired the panels to 2S. Two panels in series is making 5.5A at 109V, a reasonable voltage that most 150V controllers can handle. Take a look at Epever's Tracer 6415AN 60A controller.
1636818237442.png


Note that I'm only using a total of 2 or 3 of your 15 panels. That's because we need some more details about what you actually want to create? Do you want a DC only system that can charge the 12V batteries of your RV directly, or do you want an AC system? I see that you mentioned you want a "30amp 110 Plug", so that makes me think you want to create an AC system? Is that correct? If you simply want to create a "docking station" for keeping the RV batteries charged while at home, it might be simpler and more cost-effective to create a DC charging system only? What is your RV battery size? It's 12V, right? Do you know the maximal amps it takes? We can determine that from the batteries Amphour rating.
 

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GoingDark90

New Member
Joined
Nov 12, 2021
Messages
5
What no-one has mentioned yet is using a string calculator. I like this one.
You plug your panel values into the left panel, and see what the resulting power levels are like on the right panel.

Looking at three panels in series, the Voc around freezing is so high that only a controller that can handle 250V is recommended. What are your winter lows like? That temperature can be plugged into the calculator.
View attachment 72178

Here I re-wired the panels to 2S. Two panels in series is making 5.5A at 109V, a reasonable voltage that most 150V controllers can handle. Take a look at Epever's Tracer 6415AN 60A controller.
View attachment 72177


Note that I'm only using a total of 2 or 3 of your 15 panels. That's because we need some more details about what you actually want to create? Do you want a DC only system that can charge the 12V batteries of your RV directly, or do you want an AC system? I see that you mentioned you want a "30amp 110 Plug", so that makes me think you want to create an AC system? Is that correct? If you simply want to create a "docking station" for keeping the RV batteries charged while at home, it might be simpler and more cost-effective to create a DC charging system only? What is your RV battery size? It's 12V, right? Do you know the maximal amps it takes? We can determine that from the batteries Amphour rating.
This will be to power a 2005 camper which is what I am to believe a 12v system. Yes, A Docking station is what I want to create. I will have the full details this weekend from the Campers Plackerd on power consumption.
Mainly Lights, Fridge, water pump, propane water heater, and Heat, AC unit is not a concern for me but if works Awesome.

Thank you I wasn't expecting that amount of detail. But you all are awesome for helping me understand this. (these panels were a gift so Beggers can't be choosers :D.

Thank you
Tom
 

Rocketman

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Sep 27, 2020
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Are you thinking of adding one or two panels to the roof of the camper - to keep the batteries charged when using it. Then using the rest on a “shed” to create a small docking station. (Ok maybe not so small)?
 

GLC

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Even though you have the specs on the panels, they are used. Do you know the actual outputs on the panels? Case and point, I have 4-305 watt panels on one system. By calculations using specked data on panels, I should see a maximum of 1220 watts coming from the controller on the best day, best sun angle in the coolest time of the year. The best I have ever seen is 900 watts on the best day. Normally it is in the range of 600 to 775 watts. Just FYI, you can over panel quite a bit on some controllers and still be quite safe.
 

GoingDark90

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Nov 12, 2021
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Are you thinking of adding one or two panels to the roof of the camper - to keep the batteries charged when using it. Then using the rest on a “shed” to create a small docking station. (Ok maybe not so small)?
Depends, my goal is to have enough power to keep the lights/heat/fridge running and lights and power to the shed. I just need a big enough battery bank I am aware of. I just don't know what type of charge controller I need to use to then run a 3000w inverter which should be capable. im an electrical noob. I have 2 campers and a shed. Not worried about the AC.. so far the info is helping.
 

newbostonconst

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Sep 24, 2019
Messages
660
Peak Power 305 W
voltage 54.7 V
Current 5.58 A

Series (3) 54.7 * 3 = 165 volts....
Parallel (5) 5.58 *5 = 30 amps....

Midnight Solar 200 is pushing it at S3P5.....

S3xP3 is good....with a 250 then do another array with the other 6 panels.

1638285889371.png
 
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