Adding solar panels

[-robw-]

Site is not allowing me to edit my post so a couple of post-edits:

1) I was responding to "What is strange is that 1800watts should deliver over 60amps into a 24V battery system"
2) Max PV for 3210 is 1170w, although max charge current is 780. We both acknowledged I would be wasting some wattage but doing so was a compromise.

Why is the 2nd controller a concern? afaik, it was the only way I could wattage to system, short of purchasing another Classic 150.

[-robw-]

What is strange is that 1800watts should deliver over 60amps into a 24V battery system. Those 8 CR305 wired 2Px4S create a 610Ah 24V system which should match up to that Classic 150 just fine.

My first concern is having a second pv charging system connected to the same batteries.
My second concern is having 1080w connected to the Epever 3210 which exceeds it's max watt input by close to 300watts. Unless you point the panels in different directions you could overload the Epever.

Agreed, hence my bitch: "This is very disheartening, especially given how many tech's had told me, "Sorry, you're too light on PV. Nothing I can suggest except adding more""

62 amps is 'recommended' charge current per Crown (20% of 310), but if max current rate is 100a I should be able to go higher if situation demanded. I thought I could, and with so many tech's recommending more PV, I figured they did too. Problem is, although I have double and triple checked resistance factors, batteries won't accept more than that 62a.

That doesn't seem right unless max current rate of these Crown 305's is not 100a.

[SunEagle]

Primary system is 1800w PV connected to Classic 150
Secondary (just added) system is 1080w PV connected to Epever 3210

Both connected to 2x4 CR-305's.

I used the Epever because I was told that because the wattage of secondary panels (270w) is higher than primary panels (180w) I could not tie both into same controller.

What is strange is that 1800watts should deliver over 60amps into a 24V battery system. Those 8 CR305 wired 2Px4S create a 610Ah 24V system which should match up to that Classic 150 just fine.

My first concern is having a second pv charging system connected to the same batteries.
My second concern is having 1080w connected to the Epever 3210 which exceeds it's max watt input by close to 300watts. Unless you point the panels in different directions you could overload the Epever.

[-robw-]

Primary system is 1800w PV connected to Classic 150
Secondary (just added) system is 1080w PV connected to Epever 3210

Both connected to 2x4 CR-305's.

I used the Epever because I was told that because the wattage of secondary panels (270w) is higher than primary panels (180w) I could not tie both into same controller.

[SunEagle]

So adding to system appears to be almost a total waste of time. Whereas before my Classic 150 would consistently (on cloudless days) generate 9kWh for day, now it only generates 7kWh, leaving the other 2 kWh to the Epever 3210. Apparently, my battery bank will only accept 50-60a @ bulk. This is very disheartening, especially given how many tech's had told me, "sorry, you're too light on PV. Nothing I can suggest except adding more". I always disagreed too. 1800wh PV for a 610ah bank seemed just fine for my location.

Question, if you would: Spec sheet for CR-305 indicates "Max. Charge Current (48V)" is 100 Adc. Does that mean Max charge at 24v is half of that, or 50Adc?

2x4 CR-305, equalized every 2 weeks
6 awg wiring from CC to bank, 2/0 serial cabling
Battery temp @ 29.2C
Both controllers calibrated for 29.1v absorb for 5 hours (cause 3 hrs didn't work)

I don't think I am, but am I missing anything?

Again. With a 610Ah battery system you need about 60 amps of charging. That Epever 3210 is only a 30amp CC. While your panel system may deliver more amps while the sun shines the CC will max out at 30amps and not provide what a 610Ah system needs.

So what is your total panel wattage and how it is wired to the CC and what is their Vmp rating?

Remember that Epever 3210 is only rated 780watt for a 24V battery system but it still can only provide 30amps of charging which is not enough for a 610Ah battery system no matter what the voltage is. If you are using 2 of those 3210 type they may work together on the same battery system or they may fight each other depending on if they communicate with each other.

If you have a Classic 150 why do you need the Epever CC?

[-robw-]

With the panels laying flat you may get only 80% output which seems a waste but if you are ok with that then fine.

If you want to use more panels then you will need to increase the CC size to say 60amps or arrange the panels with half pointing to the East and the other half pointing to the West. This will allow you to charge during more of the day without exceeding the input wattage of your CC

So adding to system appears to be almost a total waste of time. Whereas before my Classic 150 would consistently (on cloudless days) generate 9kWh for day, now it only generates 7kWh, leaving the other 2 kWh to the Epever 3210. Apparently, my battery bank will only accept 50-60a @ bulk. This is very disheartening, especially given how many tech's had told me, "sorry, you're too light on PV. Nothing I can suggest except adding more". I always disagreed too. 1800wh PV for a 610ah bank seemed just fine for my location.

Question, if you would: Spec sheet for CR-305 indicates "Max. Charge Current (48V)" is 100 Adc. Does that mean Max charge at 24v is half of that, or 50Adc?

2x4 CR-305, equalized every 2 weeks
6 awg wiring from CC to bank, 2/0 serial cabling
Battery temp @ 29.2C
Both controllers calibrated for 29.1v absorb for 5 hours (cause 3 hrs didn't work)

I don't think I am, but am I missing anything?

[-robw-]

Agreed, but the extra power is just to help handle AC season when almost dead flat is best here. The rest of the year they'll help treat batteries better, I guess, but that's it.

Thanks for confirming.

[SunEagle]

With the panels laying flat you may get only 80% output which seems a waste but if you are ok with that then fine.

If you want to use more panels then you will need to increase the CC size to say 60amps or arrange the panels with half pointing to the East and the other half pointing to the West. This will allow you to charge during more of the day without exceeding the input wattage of your CC

[-robw-]

Yes, sir, exactly what I'm undertaking right now. Epever also limits total wattage at 880, but 1pm, clear blue sky and 80 degrees is only supporting 60x8, or 240w/panel (only 2 panels connected) instead of panel rating of 270w. So I waste 80w with 2x2 but still seems to be best solution.

That 240 is also about the best they'll do because they're mounted flat. Perfect for summer (when they're needed) but otherwise not tilted properly.

[SunEagle]

An odd number of panels can be a big problem with an off grid system. I would think getting a 4th 270w panel and wire them 2S2P to the charge controller should work if you do not exceed any of the Max input values.

If you go with a PWM type CC you will lose at least 33% of the panel wattage for charging. Remember PWM is Amps in = Amps out. You will also need some type of combiner box once you exceed 2 parallel panels.

[-robw-]

So, after messing around too much trying to get present under-powered system to function reliably, I decided to add 3 270w panels that I had lying around. I also have an Epever 3210 on hand. Problem is they're not compatible. Epever has an input limit of 100v and open circuit for panels - in series - is 115v.

I'd really like to use what I have on hand, so, question 1: If I parallel the 3 panels would 31v be enough to drive Epever for 24v bank? (I don't think so)
Question 2: If not, is the solution to buy a PWN instead? Or... anyone know of a cheap MPPT that works at 125vdc?

No shading or wiring issues, the latter is already established. My goal is to add an extra 20~ amps to system, a 30% increase.

Thanks