MPPT and Solar Panels for a 24V Battery

[ChainedTraveler]

I picked up a 24v 100ah LifePo4. The instructions recommend charging at 29v 20a. I have a charger coming to run with a generator or plug into a wall. What should I be looking for in regards to a set of panels and an mppt charger. The manufacturer website recommends their 40 mppt charge controller but what are my options?

 

[Tony Latham]

I picked up a 24v 100ah LifePo4.

Out of curiosity, why 24 volts? I assume you'll convert to 12 volts for your feeds?

Tony

 

[Wandering Sagebrush]

Echoing Tony’s question…

I prefer Victron components, with Bluetooth. The panels I’m using are 165 watt EcoFlow that I can configure in series or parallel, but usually just use a single panel

 

[ChainedTraveler]

Out of curiosity, why 24 volts? I assume you'll convert to 12 volts for your feeds?

Tony

Supplying to an ac inverter. I have no real need for 12v at this time. Everything I use as of now runs on ac...vent fan has an ac power supply. Cooler does ac and 12v. I plan on getting a diesel heater l, I'll make sure that it runs both too. Everything else is USB so no real need for 12v but I can add an 12v inverter if it comes up.

And I went back and forth on 12 vs 24. I wanted the higher efficiency of 24 but 12 might have been cheaper. But in the end, too good of a deal to pass up on the 24v battery made the decision.

 

[Rich796]

With an mppt charge controller. You want to make sure your solar panels are, generating enough voltage. To run efficiently. You could run 12v panels in series. Or 24/36/48v panels in parallel or series. For your 24 volt system. Depending on the mppt volt/amp/watt ratings.

Operating at higher voltages ( series ) generally means you can run smaller gage wire. From the panels to the mppt. ( because the extra power/watts is not being transferred as amps ) This really only kinda comes into play if you have a larger system.

Series panels will start charging sooner/and continue charging latter than parallel panels. ( of the same voltage ) And perform better in low light conditions. With an mppt charge controller. But, a draw back, is that all panels in series. Must be in clear sun. You can not have shading on one of the panels. Because the power flows through all of the panels in series. Where as parallel panels, power flow through each one individually.

My understanding is that mppt charge controllers. Were designed/optimized for series use. Or using higher voltage panels in a lower voltage system. Would be essentially the same scenario.

What you need to look for, is to ensure your mppt charge controller. Is rated for the voltage input you want to run at. ( solar panels V/out ) And can output enough amperage ( once converted by the mppt ) A/out. With a slight amout of head room. So that you can use all of the power generated. And or room, for future expansion, if wanted.

Edit below,

I've posted this elsewhere, and I think you need to click on it to see it fully. ( actually looks like it displayed full size this time ) But, you want to look at the DIFFERENCE between SOLAR V/in & A/in versus BATTERY CHARGING V/out & A/out. You need to make sure you pick the mppt correctly. For the power you expect to generate and use, once its converted by the mppt. The pic below, is 2 - 100watt panels in series. With a victron 75/15 mppt. So you can see I could add another panel in series 60 V/in. But it would not be able to supply any additional A/out. As its already operating at nearly max capacity ( 220w in a 12V system ) in full sun. ( Although it could supply 440w In a 24V system ) A higher charging voltage. But the same maximum of 15 amps output.

 

[ChainedTraveler]

With an mppt charge controller. You want to make sure your solar panels are, generating enough voltage. To run efficiently. You could run 12v panels in series. Or 24/36/48v panels in parallel or series. For your 24 volt system. Depending on the mppt volt/amp/watt ratings.

Operating at higher voltages ( series ) generally means you can run smaller gage wire. From the panels to the mppt. ( because the extra power/watts is not being transferred as amps ) This really only kinda comes into play if you have a larger system.

Series panels will start charging sooner/and continue charging latter than parallel panels. ( of the same voltage ) And perform better in low light conditions. With an mppt charge controller. But, a draw back, is that all panels in series. Must be in clear sun. You can not have shading on one of the panels. Because the power flows through all of the panels in series. Where as parallel panels, power flow through each one individually.

My understanding is that mppt charge controllers. Were designed/optimized for series use. Or using higher voltage panels in a lower voltage system. Would be essentially the same scenario.

What you need to look for, is to ensure your mppt charge controller. Is rated for the voltage input you want to run at. ( solar panels V/out ) And can output enough amperage ( once converted by the mppt ) A/out. With a slight amout of head room. So that you can use all of the power generated. And or room, for future expansion, if wanted.

Edit below,

I've posted this elsewhere, and I think you need to click on it to see it fully. ( actually looks like it displayed full size this time ) But, you want to look at the DIFFERENCE between SOLAR V/in & A/in versus BATTERY CHARGING V/out & A/out. You need to make sure you pick the mppt correctly. For the power you expect to generate and use, once its converted by the mppt. The pic below, is 2 - 100watt panels in series. With a victron 75/15 mppt. So you can see I could add another panel in series 60 V/in. But it would not be able to supply any additional A/out. As its already operating at nearly max capacity ( 220w in a 12V system ) in full sun. ( Although it could supply 440w In a 24V system ) A higher charging voltage. But the same maximum of 15 amps output.

View attachment 2516327

Thanks for the pointers.

 

[Tony Latham]

Everything I use as of now runs on ac...vent fan has an ac power supply.

Roger that. I think yours may be the first straight 120-volt camper here.

Tony

 

[ChainedTraveler]

Roger that. I think yours may be the first straight 120-volt camper here.

Tony

I bought a used Tiny Camper. It has a 30 amp hook up and two sets of outlets, interior and exterior. It came with two small AC units, a coffee maker and the ceiling fan/vent (12v). I found a old computer power supply in my junk drawer for the fan. So this was my starting point. Everything else I have shopped for has been AC or AC/DC compatible. And I really don't need anything else at this point except the diesel heater which will also be AC/DC. I have LED/usb lighting, gas cooking, AC cooler/freezer, electric coffee, I'll throw a LED TV into the trailer when I go camping. About the only place I can fall short is my small air compressor that is 12v but I can run that with the car when I need it. I can also add a small 12v inverter into the battery box at a later date which I may do. It might be a better option to run the fan and fridge instead of having the constant draw of two power supplies.