Newbie startup questions.

[Gdwats]

Greetings all. Just starting out..I have 2 renogy 100W mono panels in parallel, the renogy 20A rover mppt, 1 Chrome 55ah 12v deep cycle and a 500W inverter. I have questions.
I am getting another 55ah duplicate battery, and will be getting one or 2 more panels to complete this system. I plan on connecting the battery in parallel, same with 3rd and 4th panels. Would it be better to keep everything in parallel since the batteries will be 12V? 4 panels may be pushing the 20A CC as each panel puts out a little over 5A, or does it not matter as long as I don't draw more than 20A?
Thanks,
Greg

[max2k]

Greetings all. Just starting out..I have 2 renogy 100W mono panels in parallel, the renogy 20A rover mppt, 1 Chrome 55ah 12v deep cycle and a 500W inverter. I have questions.
I am getting another 55ah duplicate battery, and will be getting one or 2 more panels to complete this system. I plan on connecting the battery in parallel, same with 3rd and 4th panels. Would it be better to keep everything in parallel since the batteries will be 12V? 4 panels may be pushing the 20A CC as each panel puts out a little over 5A, or does it not matter as long as I don't draw more than 20A?
Thanks,
Greg

does your charger / inverter support 24V? If so then you could connect panels in parallel and batteries - in series. Trouble is panels and batteries are sort of opposite in certain sense: panels produce current and 2 currents can be connected in parallel. Batteries produce voltage and connecting them in parallel usually ends up badly with only one working and eventually dying from overload / overcharge as it's impossible to make 2 identical batteries that would also age identically. Connecting them in series avoids this trouble but still allows storing twice the energy.

[SunEagle]

If you are enlarging to 400 watts then you need to get a true MPPT CC rated 30 amps or you can push that 400 watt into that 20Amp CC (which I doubt is an MPPT type) but will probably lose over 100 watts of charging capacity.

Otherwise you can go with 3 x 100 watt panels wired in parallel with fuses to that 20amp CC. But you will need a battery system rated about 110Ah so while I don't usually recommend wiring batteries in parallel you could get away with 2 of those 55Ah type to create a 110Ah 12v battery system.

[Gdwats]

Ok. Thanks much for the info. The CC is a renogy rover 20A mppt with 4 charging stages, I'm not sure why you'd think it was not mppt?
Anyway, I have a less than one week old now 55AH deep cycle sla battery, and a second coming by Monday of same model so that's 110AH. The CC can tell btw 12/24v automatically yes. I am just running the tv and home led lighting off it now via a 500W ac inverter(not pure sine), and I think it is a 12V inverter and wont run on the 24v batteries in series that you mentioned, I'll double check.
I ordered the 3rd panel today and may stop there, and later have a second system at 24v with a pure sine 1000W inverter. The smaller system will be just for tv, devices and led lighting.

[Gdwats]

Should I charge this battery until 14.1v , then charge second one to 14.1v before connecting them in parallel (my inverter is 12v only)?
thanks

[SunEagle]

Should I charge this battery until 14.1v , then charge second one to 14.1v before connecting them in parallel (my inverter is 12v only)?
thanks

You could actually charge 2 x 55Ah batteries wired in parallel using your 200watts which should be enough depending if that is a true MPPT CC. If it is really a PWM type CC then you will get less charging amps but it should be enough to replace 25% of the battery charge.

[Sunking]

14.8 volts, not 14.1

[Gdwats]

I keep hearing this "if". Is there something I should know about the Renogy Rover 20A mppt cc ? Are they not really mppt but just emulate a false 4-stage output, like Volkswagen did with their cars? I don't understand.

And I was just asking if I should charge both batteries up before connecting them together. Still have no answer.

[Gdwats]

"Gel-cell batteries and other sealed batteries should never be charged to more than about 14.1 volts ". Why would you correct me to 14.8 please?

[littleharbor]

It appears to be a MPPT controller. The max. Voc is 100 volts. You need to be careful not to over volt . You can safely series wire up to 3 of the 12 volt 100 watt panels together. A fourth panel would be too much power for a 20 amp controller.
The 4 stage charging mentioned really has nothing to do with MPPT.
You did mention 55Ah. sla batteries. Are they, in fact GEL?

[Gdwats]

Yes. 2 x 55AH ChromeBattery deep cycle sealed lead acid. Gonna stick with 3 100W panels at 12v in parallel that will generate at most 15.9A into the controller and the 2 batteries, also in parallel for 110AH @12V to a 12v only 500W inverter (will be getting 2nd system later) workable?

[Gdwats]

It appears to be a MPPT controller. The max. Voc is 100 volts. You need to be careful not to over volt . You can safely series wire up to 3 of the 12 volt 100 watt panels together. A fourth panel would be too much power for a 20 amp controller.
The 4 stage charging mentioned really has nothing to do with MPPT.
You did mention 55Ah. sla batteries. Are they, in fact GEL?

Well, mppt is one stage. There is also a boost stage, constant stage, and a 4th equillization stage that doesn't apply to sla DC batteries as i understand it.

[max2k]

Well, mppt is one stage. There is also a boost stage, constant stage, and a 4th equillization stage that doesn't apply to sla DC batteries as i understand it.

usually MPPT relates to how charge controller / inverter takes energy from the panels, basically CC input.

Some marketing department could decide to break down some system into 'stages' creating confusion as 3 other 'stages' you listed relate to stages of the battery charge process meaning - the CC output.

[littleharbor]

Well, mppt is one stage. There is also a boost stage, constant stage, and a 4th equillization stage that doesn't apply to sla DC batteries as i understand it.

The usual terms applied to PWM charging are 1, Bulk, 2, Absorb, 3, Float, and 4,Equalize. This Mfg. has chosen to use different terms for this. You don't have to have a MPPT controller to charge in this way. with the exception of Equalization virtually all charge controllers use this algorithm. The cheaper controllers don't have equalize function.

[Sunking]

"Gel-cell batteries and other sealed batteries should never be charged to more than about 14.1 volts ". Why would you correct me to 14.8 please?

My bad, that is why you do not want gel batteries. Instead of buying more inappropriate batteries of the wrong size, why not be smart and just replace the batteries with the right kind and size.

Never Ever use Gel Batteries or install batteries in parallel. You have no reason other than ignorance. A Gel battery cost 2 to 3 times more than a good old flooded lead acid aka FLA. Gel batteries only last half as long as FLA, and cut that in half again if you installed them in parallel. So in th eend you pay 800% more for Gel batteries. Don't be stupid.

I have 2 renogy 100W mono panels in parallel, the renogy 20A rover mppt, 1 Chrome 55ah 12v deep cycle and a 500W inverter. I have questions.
I am getting another 55ah duplicate battery, and will be getting one or 2 more panels to complete this system.

No Sir you will not do that. I refuse to let you do that.....


Don't be Stupid and waste your money. If you get 2 more panels will be a total of 400 watts right? Guess what genius? You would need a new 30 to 40 Amp MPPT CONTROLLER. Your 20 amp controller is maxed out at 240 watts.. Don't be stupid.

Another Battery Rule. Never ever mix old and new batteries. That 3rd battery you planned on buying will be just as old and weak as the older batteries in a month. Now you need to replace all three of them. Don't be stupid.

It is time to make things right and quit being ignorant. Buy two more panels for a total of 400 watts, upgrade the Controller to a good and real 45 - Amp MPPT Controller , and a pair of Trojan 6-volt 225 AH Golf Cart batteries model T-105 or T-105RE. A pair of trojans will be about the same price as that POS 12 volt 55 AH Gel Battery of around $300. . . You end up with more capacity of 225 AH vs 165 AH Gel. Not the parallel garbage you have now. That is what SMART MONEY WOULD DO. Are you smart enough?

Lastly rewire your panels in series when you get upgraded. You will want 2S2P aka 2 panels in Series and 2 strings in Parallel