Recommend 48V Inverter for Solar/Powerwall Project

garolittle

garolittle

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Oct 27, 2017
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Hello all. This forum is awesome. I am new to the DYI Powerwall world.Any recommendations for a 48V Inverter for the following:

Project: Solar andPowerwall for camping and emergency backup power

Setup:13S8P configuration using new LG MJ1 3500 mAh 18650 battery cells connected with pure nickel strips

48V 13s BMS charging current 15Amps discharge current 30Amps

DROK MPPT Solar Panel Battery Charge Controller With Boost Voltage Converter Regulator DC 12-60V Step Up to DC 15-90V for 24V/36V/48V/60V/72V 0-10A Battery Pack Charging

WindyNation 100 Watt flexible solar panel
Open Circuit Voltage: 21.60 Volts
Flexible Thin Lightweight Solar Panel
Short Circuit Current: 5.97 Amps
Max Power Voltage: 17.8 Volts
Max Power Current: 5.62 Amps

Thanls for any suggestions on a 48V Inverter or any other recommendations for this project.
 
My first recomendation is to go to 14s instead. Then you dont have to go to the low voltage on your choosen inverter. You also gets less current flowing and therefore slightly thinner wires.


For that small system you want something very efficient. But you never said whats your max Watt you wannt to be able to pull is? Note that with that rather small battery bank I wouldnt go above 2kW MAX..... And for longeivity half that max. Preferable even lower.
 
Thank you for the response. The maximum will be 1,000 watts since it will only be used for very small appliances for short periods of time. I appreciate any other suggestions you may have.
 
If you only look for a simple inverter I guess the inverter should be in the range of like the charger and panel you choose. I guess any pure sinewave 1kW continous would work. I have no one to recommend except for more expensive like Victron units.
 
daromer said:
If you only look for a simple inverter I guess the inverter should be in the range of like the charger and panel you choose. I guess any pure sinewave 1kW continous would work. I have no one to recommend except for more expensive like Victron units.
Click to expand...

Thank you Sir. I really appreciate the response.
 
Xantrex Pro xm series would be a good inverter for this setup. Your solar panel is made for 12v charging so why nit go with a 12vdc system? There is less loss using a straight mppt charge controller then trying to step up voltage like your doing. For off grid you either build the system around the inverter you want to use( in your case more panels and 60-72 cell) or the solar panel if only using one. Just my 2 cents worth.
 
kennl said:
Xantrex Pro xm series would be a good inverter for this setup. Your solar panel is made for 12v charging so why nit go with a 12vdc system? There is less loss using a straight mppt charge controller then trying to step up voltage like your doing. For off grid you either build the system around the inverter you want to use( in your case more panels and 60-72 cell) or the solar panel if only using one. Just my 2 cents worth.
Click to expand...

Connecting the panels in series will yield 48V. I don't see why he'd have to stay with 12V. 12V in very hard to setup with lithium cells and conversion from 12V DC - 120V AC is not very efficient. Not to mention all the cabling from the solar panel to the storage/charger and all other connections up to and including the inverter would need to be heavy duty to minimize losses. Not to mention the bigger the cable, the harder it is to work with.
There is nothing wrong with MPPT, as long as you get a proper unit that functions as it should. And to do so, you are either gonna be shooting in the dark with cheap knock-offs, or you're going to have to have to shell some bucks for a "professional" unit.
In the long run, 48V would be cheaper to operate, maintain, and have a pretty optimal conversion efficiency to AC.
 
Korishan said:
kennl said:
Xantrex Pro xm series would be a good inverter for this setup. Your solar panel is made for 12v charging so why nit go with a 12vdc system? There is less loss using a straight mppt charge controller then trying to step up voltage like your doing. For off grid you either build the system around the inverter you want to use( in your case more panels and 60-72 cell) or the solar panel if only using one. Just my 2 cents worth.
Click to expand...

Connecting the panels in series will yield 48V. I don't see why he'd have to stay with 12V. 12V in very hard to setup with lithium cells and conversion from 12V DC - 120V AC is not very efficient. Not to mention all the cabling from the solar panel to the storage/charger and all other connections up to and including the inverter would need to be heavy duty to minimize losses. Not to mention the bigger the cable, the harder it is to work with.
There is nothing wrong with MPPT, as long as you get a proper unit that functions as it should. And to do so, you are either gonna be shooting in the dark with cheap knock-offs, or you're going to have to have to shell some bucks for a "professional" unit.
In the long run, 48V would be cheaper to operate, maintain, and have a pretty optimal conversion efficiency to AC.
Click to expand...

I'm not seeing where he says he has more then one and since he's using a step up kinda of figured the quantity was 1. Otherwise no reason for the step up.
 
Thank you both for your comments. This is really great information. I was planning to use only one solar panel however based on the information just provided it sounds like I should use more than one in order to get the charging voltage up to 48 V. My ultimate goal is to maximize efficiency so this may be the best path forward. I really appreciate the feedback. I am really looking forward to this project so any additional advice is welcome (recommended wire gauge size into/out of the battery bank, ect)
 
Wire gauge size is dependent on the amperage you plan to run with minimal voltage drop. So, figure out what the amps you need, then you figure out the wire you need. However, going from the battery (not from packs to packs) to the charger and/or inverter, I would go no smaller than 8 awg. that will allow you to pull at least 100amps if needed without issues.
Please look through other builds listed to answer unknown questions you may have, to get some other ideas on design, layout and general construction, and to gain more detailed information about the projects, the electronics, the wiring, and the configurations. It is quite possible you may not even know what to ask if you don't know what you don't know :)
 
It is quite possible you may not even know what to ask if you don't know what you don't know

Very true. I am so eager to start the project but I really need to take the time to learn the fundamentals. Im absolutely addicted to the idea of storing sunshine in a battery and using it at a later time. However, I know I need to keep learning so I will take that advice. This form is awesome. Thanks again for all the advice. I will keep everyone posted on my progress.
 
Google "dc power cable sizing calculator" and you'll find some good wire calculators that are easy to use. FYI my background is electrical for the last 30 years. 75% of my house has been off grid for the last 10 years and I had to go through the learning curve your facing now.

Good luck with your project, I'll be watching :cool:
 
Thanks kennl. I followedyour advice and found some great tools. I really appreciate the information. So much to learn. :D
 
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