What kind of solar charge controller

[Scottish dan]

Hi all
I’m very new to solar so require some advice on solar charge controller
The image below are solar panels I have bought , I have 3 in total
What size of solar charge controller do I need

Sorry for my lack of knowledge

any help appreciated

thanks

 

[DThames]

What is the battery voltage that you plan to charge? For a 24v battery, using an MPPT charger, a 10amp would be okay if you had a small sized battery, but a little under powered and not able to use full panel power during the best conditions. So 20amp would be better to get max power of your panels. For a 12v battery, double the amp rating...30 or 40 amp. If you want to add more panels someday, round up.

Assumption, is you want an MPPT charge controller.

 

[Scottish dan]

Yes it will be for 24 v . Will the 10 amp controller be enough for the 3 panels

 

[DThames]

Yes it will be for 24 v . Will the 10 amp controller be enough for the 3 panels

A 10 amp should max out at 10 amps. For a couple of hours a day if the sky is clear, you might get between 15 and 20 amps you could send to your battery under ideal sky conditions. So the 10amp would be undersized, UNLESS you have a small battery that would not link 15 amps, then the 10amp would be best. So it all depends.

 

[Forbisher]

Yes it will be for 24 v . Will the 10 amp controller be enough for the 3 panels

195w x 3 = 585w ÷ 24V = 24A

 

[Scottish dan]

So in theory round this up to 30 amp

 

[cwstnsko]

You could probably get by with a 20a MPPT controller and still get full production on warm and overcast days, but the cold sunny days you will lose some output. A 30a SCC will give you more certainty of getting the most from the panels. With those panels, I'd probably look for a SCC with at least 150V max input to allow you the flexibility to run them in series. It may make the wiring less expensive.

 

[CoachMcG]

I have a 24V inverter/charger (Samlex 2224) and 4x12v sealed AGM 82.5Ah, connected in series/parralel. Manufacturer recommends max charge 25amps. I'm planning to buy 2x270 watt 24V panels. If i understand correctly, i should get a 30amp mppt? I'm guessing i could set it to charge at max 25Amps? On the right track?

 

[cwstnsko]

I have a 24V inverter/charger (Samlex 2224) and 4x12v sealed AGM 82.5Ah, connected in series/parralel. Manufacturer recommends max charge 25amps. I'm planning to buy 2x270 watt 24V panels. If i understand correctly, i should get a 30amp mppt? I'm guessing i could set it to charge at max 25Amps? On the right track?

Are you talking about setting the samlex to limit charging to 25a or the mppt controller? Many mppt controllers don’t allow you to set a current limit, but at 540W, you should be under 25a at max output anyway. I’m not sure if the samlex charging current can be set that low.

 

[CoachMcG]

I have set the samlex at 25Amps. It's default setting is 40Amps. My question is... Is it waste to have a 60Amp Charge controller if i can't charge at more than 25?

Rookie here... refresh my memory as to how you come up with 'at 540W i should be under 25amps Max output'. Is it 540/24=22.5? What if i buy 2x320? 640/24=26.7. I'm guessing i wouldn't get max output because conditions would have to be ideal. And if i did, my inverter would limit my charge to 25Amps regardless right?

Thanks for your help!

 

[cwstnsko]

Yes, that is the most basic math . Even at 640W, you would probably be below 25a because the battery voltage is somewhat higher than 24 and the panels would only produce full output under theoretical perfect conditions. The specs I saw on the Samlex 2224 was for up to 70a charging, I don’t believe the samlex will limit the current coming from the solar charge controller at all, I think it just provides a connection point, if you want to wire it that way. For the panels you are talking about, a 60a charge controller would be overkill.

 

[CoachMcG]

Thank you! 60Amp overkill is what i thought yet it was recommended by two seperate vendors... it pays to research!