My solar plan—thoughts please

[KateC]

So I’m getting ready to hit checkout on the rest of my solar setup, but wanted to run it by you knowledgeable folks.

I’ll have 200-300w solar panels wired in parallel with 10 awg with 30a inline fuses to a renogy 50a dc-dc charge controller with mmpt. 4 awg from the starter battery with a 60a fuse running to the charge controller, too. 4 awg with 70a fuse from the cc to a Victron lynx distributor.
From the Lynx distributor:
—2/0 awg with 350a fuse (with on/off switch) to a 280ah varicore lifepo4 battery wired 4s with a 250a Daly bms with a shunt and battery monitor.
—4 awg with 100a fuse to a blue seas fuse box
—4/0 awg with 350a fuse to a 3000w inverter

Shore power also running to the inverter with 10/3 awg. (Does this need a fuse or breaker or anything? My understanding is that it doesn’t)

Inverter output through 10/3 awg to circuit breaker for ac outlets. Three outlets on a single circuit is what I’m planning on.

Does anyone see any problem with any of this? As of right now, the only pieces I have already are the battery and the dc-dc charge controller. Thank you!

 

[rmaddy]

A 3000W inverter on a 12V system can pull 300A. You need 4/0AWG wire between the battery and inverter. You list 4/0AWG to the inverter but you list 2/0AWG at the battery. Change that 2/0 to 4/0.

You have a 250A BMS. But you need 300A to use the full 3000W of the inverter. You need a bigger BMS or two batteries in parallel.

What will your exact panel arrangement be? What wattage each and how many? What are the full specs of the panels?

 

[KateC]

A 3000W inverter on a 12V system can pull 300A. You need 4/0AWG wire between the battery and inverter. You list 4/0AWG to the inverter but you list 2/0AWG at the battery. Change that 2/0 to 4/0.

Even though it’s all going through the lynx distributor?

What will your exact panel arrangement be? What wattage each and how many? What are the full specs of the panels?

I don’t know exactly yet. I have a roof fan and a skylight, so I have somewhat limited space. Definitely a 200w rich solar panel, but there’s enough room for another smaller panel too. Maybe a 50w or something, but I’ll probably hold off on that and see how the 200w does alone.

Specifications:​

Maximum Power(Pmax): 200W
Maximum Power Voltage(Vmp): 20.4V
Maximum Power Current(Imp): 9.80A
Open Circuit Voltage(Voc): 24.3V
Short Circuit Current(Isc): 10.2A
Maximum System Voltage(Vmax): 1000V DC

 

[WYtreasure]

So I’m getting ready to hit checkout on the rest of my solar setup, but wanted to run it by you knowledgeable folks.

I’ll have 200-300w solar panels wired in parallel with 10 awg with 30a inline fuses to a renogy 50a dc-dc charge controller with mmpt.

Welcome to the show KateC.

I know nuthin about everything but can you clarify how many panels you have. I'm thinking you do not have (quantity) 200 and (wattage) 300 panels.
I've seen folks here saying not to mix-n-match panels with any appreciable difference.

I get confused easily.

Welcome anyhow

 

[rmaddy]

Even though it’s all going through the lynx distributor?

That's irrelevant. You can't use 2/0AWG wire for a 300A load. 2/0AWG is only good for up to 200A loads.

Definitely a 200w rich solar panel, but there’s enough room for another smaller panel too. Maybe a 50w or something, but I’ll probably hold off on that and see how the 200w does alone.

For a single panel you don't need any fuses between the panels and the charge controller. Just make sure that 50A charge controller has a high enough max input voltage to support that panel. Since the panel has a Voc of 24.3V make sure the charge controller handles at least 29V.

 

[12VoltInstalls]

4/0 awg with 350a fuse to a 3000w inverter

Do you need a 3000W inverter?
That’s maybe a place to save some money on the inverter and cabling if you don’t really need 3000W- and buy more panels or at least one.

I’ve been running my off-grid camper for ~4 years with a 1200W inverter. I don’t have a microwave or an induction plate but I do use a vacuum, coffeemaker, and an electric refrigerator without straining the inverter. Maybe 3 or 4 times I’ve wanted a microwave for leftovers. 1200W is plenty in my case.

I might avoid renogy charge controllers.

 

[KateC]

That's irrelevant. You can't use 2/0AWG wire for a 300A load. 2/0AWG is only good for up to 200A loads.


For a single panel you don't need any fuses between the panels and the charge controller. Just make sure that 50A charge controller has a high enough max input voltage to support that panel. Since the panel has a Voc of 24.3V make sure the charge controller handles at least 29V.

Welp. It’s max is 25v. It looks like the other 200w panels I’ve looked are the same. Would I just need to get smaller panels or is there some way to limit voltage?

Another dumb question: if the panel had a voc of say 20, and I used two, does the voltage combine to 40 or stay the same? I don’t know how to word that for Google

 

[KateC]

Do you need a 3000W inverter?
That’s maybe a place to save some money on the inverter and cabling if you don’t really need 3000W- and buy more panels or at least one.

I’ve been running my off-grid camper for ~4 years with a 1200W inverter. I don’t have a microwave or an induction plate but I do use a vacuum, coffeemaker, and an electric refrigerator without straining the inverter. Maybe 3 or 4 times I’ve wanted a microwave for leftovers. 1200W is plenty in my case.

Yeah, I might size it down. I haven’t ordered it yet.

I might avoid renogy charge controllers.

This I have already gotten and it’s past the return window ? I guess there’s always reselling it if it really is that bad

 

[12VoltInstalls]

Would I just need to get smaller panels or is there some way to limit voltage?

Get a different charge controller.
Epever has 100V and 150V options

This I have already gotten and it’s past the return window

I guess there’s always reselling it if it really is that bad

Oops. There’s things that can me done like buying 100W panels with low VOCs to make that work.

 

[KateC]

Get a different charge controller.
Epever has 100V and 150V options

I didn’t see one with the battery to battery option. Do you know if they make one?

 

[TorC]

If you put panels in parallel, the voltage stays the same, but the amperage goes up. For your panels, Voc 24.3V, Isc 10.2A, figuring for two of your panels in parallel for your SCC you should make sure Vin 24.3V, current in 20.4A is within spec. If your SCC really is 25Vin max, you need a different on, as 12VoltInstalls says.

If there isn't a good reason to use 12V, as in lots of 12V equipment already or other need to interface with an existing system I'd go to at least 24V battery. Much easier on wiring for large loads.

 

[rmaddy]

Welp. It’s max is 25v. It looks like the other 200w panels I’ve looked are the same. Would I just need to get smaller panels or is there some way to limit voltage?

Another dumb question: if the panel had a voc of say 20, and I used two, does the voltage combine to 40 or stay the same? I don’t know how to word that for Google

As stated, buy a better charge controller. Renogy's combined DC-DC charger and solar charge controller is more of a toy. Buy a quality DC-DC charger and a quality solar charge controller. Each separate device should be chosen to handle your needs.

Things in series you add the voltage and keep the amps the same. Things in parallel you keep the voltage the same and add the amps.

 

[12VoltInstalls]

I didn’t see one with the battery to battery option. Do you know if they make one?

I don’t. But DC2DC can be acquired separately.

Either way for a van and only a few panels buying 100W panels that work isn’t a big deal because expansion isn’t really possible so the limits may not matter.

 

[KateC]

As stated, buy a better charge controller. Renogy's combined DC-DC charger and solar charge controller is more of a toy. Buy a quality DC-DC charger and a quality solar charge controller. Each separate device should be chosen to handle your needs.

Anyone want to buy a renogy charge controller? ??‍ I might just get a good charge controller and not worry about connecting the starter battery for now. If space allows and I need it, I can always get a separate one later

Things in series you add the voltage and keep the amps the same. Things in parallel you keep the voltage the same and add the amps.

I do remember that now. My brain feels too full sometimes.

 

[TorC]

A small multi-chemistry charger isn't that much, and if you're just looking to maintain a starter battery in a rarely driven camper I wouldn't worry too much about tying them together. If space is at a premium LFP has a significant advantage over LA, along with being less weight.

 

[12VoltInstalls]

might just get a good charge controller

Define ‘good’
Victron VS Epever almost seems like the good low priced and the good higher priced

 

[KateC]

Okay, so for a new charge controller, I need something that can handle around 30v from the solar. I haven’t researched charge controllers (obviously ?) as much as other components, so are there any other specs I should be looking for?

 

[12VoltInstalls]

if you're just looking to maintain a starter battery

I believe they want to have charge-while-driving

 

[KateC]

Define ‘good’
Victron VS Epever almost seems like the good low priced and the good higher priced

Imma probably go the victron route. Mama’s paying for private school too

 

[12VoltInstalls]

Okay, so for a new charge controller, I need something that can handle around 30v from the solar. I haven’t researched charge controllers (obviously ?) as much as other components, so are there any other specs I should be looking for?

The 20A Epever will take 100V input and cost is affordable. Victron is more money.