Need advice on rv set up

[Ho jo]

Sensij i looked at the 4210.would positive ground be a problem on a rv? What about the 8215 negative ground 150 volt?

[sensij]

Sensij i looked at the 4210.would positive ground be a problem on a rv? What about the 8215 negative ground 150 volt?

Yeah, if your battery negative is grounded to the chassis, the positive ground CC probably isn't the best choice. The 4215BN is slightly more expensive, but should be a better fit. The 150 V won't help much with your current design, but if you ever move up from a 12 V system to 24 V, you'll have the ability to get more PV in the system without increasing amps (wire size) or number of parallel strings (requiring overcurrent protection).

[Ho jo]

So with 4215bn rated at 520 watts could take 600 watts and just clip at 40 amps

[Ho jo]

Wouldn't that be hard on the charge controller and short lived?

[sensij]

Wouldn't that be hard on the charge controller and short lived?

Not any harder on it than running at 520 W. The charge controller adjusts the PV voltage away from Vmp if necessary so the array only ever produces 520 W. The extra energy is just sunlight on your array that is not converted to electricity... it is *not* burned up as heat at the controller.

Given how rarely a 600 W system would ever produce more than 520 W in real world conditions, the amount "lost" to clipping is insignificant in every possible way.

[Ho jo]

I've been reading on it and it's set for agm need the meter to set for lead acid around $220 for cc and meter and 2 more panels 250. $470 Would this set up double my daily out put from 400 watts on pwm? If so just in winter or how much would I gain in summer months..I could double my watts with pwm for about $540

[sensij]

I've been reading on it and it's set for agm need the meter to set for lead acid around $220 for cc and meter and 2 more panels 250. $470 Would this set up double my daily out put from 400 watts on pwm? If so just in winter or how much would I gain in summer months..I could double my watts with pwm for about $540

I'd guess in winter you'll come close to doubling output with mppt. In summer, you'll still get at least 50% more just from the two new panels, and maybe another 15% out of the older panels? . I understand your thinking, and yeah, it is a tough call. 2 panels + mppt vs 4 panels + pwm. The additional mounting and wiring costs of the PWM would probably be enough to convince me to go with mppt.

[Ho jo]

Thanks so much for helping. I can't afford to keep blindly throwing money into solar with no knowledge. Alot of solar systems are for hobbies. Mine is my way of living. Wow 15% increase on my old panels by summer they degrad that much the first year? My fute plans are building a cabin on grid with solar assistance on 24 volt. With one of mikes cc. Question is my panels are renogy mono 22.5 18.9 volt. 5.75 5.29 amp. Could I on mppt combine 4 poly 22.4 17.8. 5.92 5.62. If so what would be my loses by not having the same panels. I can get these new for 75 each

[J.P.M.]

I can't afford to keep blindly throwing money into solar with no knowledge.

Most folks can't. But if what's often shown up here is any indication, that's not much of a concern.

[Ho jo]

What are the pros and cons to use 2 of the same pwm controllers on two arrays using identical panels?

[Mike90250]

You can only use one controller per panel array.

You can use several chargers on one battery

You should NOT use more than one controller per array, they will fight each other for control of the array, and your harvest will loose

[Ho jo]

Can you run one array on pwm and one on mppt. On mppt would all panels need to be the same imp and voc.

[sensij]

Can you run one array on pwm and one on mppt. On mppt would all panels need to be the same imp and voc.

You have, in at least three different threads now, been wrestling with this design. With mppt, the panels don't have to be identical, but some effort towards matching can pay off. The poly panels are a close enough match to the mono, and will cost you very little in mismatch losses.

As I understand it, your best design at this point is to buy 200 W more and the 4125bn mppt controller. You will be fine with teh 8 AWG you are already using. Buying 400 W plus a PWM controller is about the same cost for equipment, but because you have such a long run, the wiring cost / losses really tip the scale.

Are there other factors to consider that you haven't brought up yet?

[Ho jo]

Think that pretty much covers it 4125 bn 2 more panels then when I get my cabin on grid I can use it on 24 volt by wiring my batteries in series.