diy solar

diy solar

Another new guy, building a home battery backup system.

Oh boy, this is fun!!

I have doubled the battery capacity, so now 400ah at 24 volts ... or 10kWh of storage. I made new 2AWG cables for the batteries to the bus bars and still have a little more tidying up to do, but the system is back up and running. Still debating if I need to install the 300 amp main fuse and where will it go.

Future plans: I need to lengthen and reroute the charge controller negative. I had to remove my 12 volt and 120 volt outlets because I ran out of room, so need to find a spot for those. I also need to secure the batteries to the shelf and make a cover for them. Right now they are just sitting there. We don't get earthquakes, but I still don't like the idea of the batteries being able to get pulled off the shelf. I am working on getting a match for the 150 amp BMS on the left, to replace the 100 amp on the right bank.

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I dont like your choice in fuses.
Those are automotive class, not suited for the punishment 400Ah of lithium can dish out.
Please invest in some t-fuses with t-holders.
Also, consider a steel enclosure for the batteries.
Too many entries in the smoke forum for my taste.
 
I dont like your choice in fuses.
Those are automotive class, not suited for the punishment 400Ah of lithium can dish out.
Please invest in some t-fuses with t-holders.
Also, consider a steel enclosure for the batteries.
Too many entries in the smoke forum for my taste.
Thanks for the heads up. Can I ask what is wrong with these? Bought them with the battery.

I was runnning this 300 amp in the main inverter positive. I need to make up another cable and find a place for it. And I have been thinking about welding up a metal cabinet for the batteries.

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Automotive fuses do not deal with the DC arc potential of a multi thousand amp short circuit…
T-type fuses do.
If something bad happened to any of the equipment, that bank of batteries can turn your wall, and all plastic around it into a flame fueled by a bank of electrolyte.
A t-type dc fuse has a sand arc extinguish feature that properly trips when overload occurs.
 
Today was a very dark, overcast and slightly drizzly day and the solar panels aren't making any power, so I did a stress test. Plugged a 12,000 btu window air conditioner into the system and set it to High. Also, refrigerator and phone stuff are always running off of the system. Then I plugged the little 2200 watt inverter generator into the Multi and started it up.

The system ran for 2 hours and even managed to put some charge into the batteries. I shut down the generator to top off the gas tank, then restarted and the air conditioner and refrigerator didn't even hiccup. Fantastic! I did a few things like open the fridge doors and turn on an electric kettle. Switching from grid to inverter to assist was seamless.

The only issue I could find today was one plug on the extension cord I used for the generator got a little warm so I limited 120 AC input into the Multiplus at 10 amps. I already have some 10 AWG cable to build a bigger generator cord and my next project is to build a permanent generator input into the house. Then I should be able to run the 120 AC input at 15 amps to charge the battery faster.

Future project: My wife has figured out how to configure a Raspberry Pi to run the Victron Venus monitoring software, now I need to order a few things to make that happen.
At what latitude is your property? What you're doing is very close to what I would like to do, but I live at 38 degrees north and don't have good solar exposure due to a large tree on the property, so would have to adjust accordingly.
 
At what latitude is your property? What you're doing is very close to what I would like to do, but I live at 38 degrees north and don't have good solar exposure due to a large tree on the property, so would have to adjust accordingly.
Around 30º. South Louisiana.
 
There is a storm brewing in the gulf and we have a couple of days before it might get here BUT I hadn't really pushed the backup system since I doubled the battery, so, yesterday I plugged in the window air conditioner plus all the regular stuff I would want to run during a power outage. I ran the system for 5 hours during the middle of the day and with the solar panels adding in some watts between the clouds I got down to 50% of battery capacity while using approximately 1.2kW per hour. No issues to report. Just for fun I also boiled water in an electric kettle and ran a hair dryer for a few minutes, pulling almost 3000 total watts. That finally managed to get one connection a little bit warm.

Then as the sun went away I plugged in the gas generator and in a couple of hours added 30% charge back into the batteries, all while everything kept running. I estimate I can run the air conditioner about 7 hours over night if I have to. I didn't really design the system to do that but pleased it can. The house didn't get over 80ºf yesterday with the outside tamps in the 90s. I think I am good to go. Today I need to pick up any loose things from the yard.

Also, I got a call last evening to go out and troubleshoot my Dad's whole house generator that had a "check battery" yellow light. Turns out it was just corroding battery cables on the starter battery. It sure is nice to have the whole house running automagically during a power outage, but damn that thing is loud.
 
There is a storm brewing in the gulf and we have a couple of days before it might get here BUT I hadn't really pushed the backup system since I doubled the battery, so, yesterday I plugged in the window air conditioner plus all the regular stuff I would want to run during a power outage. I ran the system for 5 hours during the middle of the day and with the solar panels adding in some watts between the clouds I got down to 50% of battery capacity while using approximately 1.2kW per hour. No issues to report. Just for fun I also boiled water in an electric kettle and ran a hair dryer for a few minutes, pulling almost 3000 total watts. That finally managed to get one connection a little bit warm.

Then as the sun went away I plugged in the gas generator and in a couple of hours added 30% charge back into the batteries, all while everything kept running. I estimate I can run the air conditioner about 7 hours over night if I have to. I didn't really design the system to do that but pleased it can. The house didn't get over 80ºf yesterday with the outside tamps in the 90s. I think I am good to go. Today I need to pick up any loose things from the yard.

Also, I got a call last evening to go out and troubleshoot my Dad's whole house generator that had a "check battery" yellow light. Turns out it was just corroding battery cables on the starter battery. It sure is nice to have the whole house running automagically during a power outage, but damn that thing is loud.
Loud is exactly the reason I'm hoping to get a solar backup system in place. We live in a fairly dense suburban area, and even if I had enough fuel on hand to run my generator I really don't want to either annoy our neighbors or attract any undue attention.
 
There is a storm brewing in the gulf and we have a couple of days before it might get here BUT I hadn't really pushed the backup system since I doubled the battery, so, yesterday I plugged in the window air conditioner plus all the regular stuff I would want to run during a power outage. I ran the system for 5 hours during the middle of the day and with the solar panels adding in some watts between the clouds I got down to 50% of battery capacity while using approximately 1.2kW per hour. No issues to report. Just for fun I also boiled water in an electric kettle and ran a hair dryer for a few minutes, pulling almost 3000 total watts. That finally managed to get one connection a little bit warm.

Then as the sun went away I plugged in the gas generator and in a couple of hours added 30% charge back into the batteries, all while everything kept running. I estimate I can run the air conditioner about 7 hours over night if I have to. I didn't really design the system to do that but pleased it can. The house didn't get over 80ºf yesterday with the outside tamps in the 90s. I think I am good to go. Today I need to pick up any loose things from the yard.

Also, I got a call last evening to go out and troubleshoot my Dad's whole house generator that had a "check battery" yellow light. Turns out it was just corroding battery cables on the starter battery. It sure is nice to have the whole house running automagically during a power outage, but damn that thing is loud.
Damn, Ida forecast to make landfall in Louisiana as a Cat 4 hurricane - hunker down and best of luck!
 
Loud is exactly the reason I'm hoping to get a solar backup system in place. We live in a fairly dense suburban area, and even if I had enough fuel on hand to run my generator I really don't want to either annoy our neighbors or attract any undue attention.
I don't care aout annoying my neighbors ... they all have loud generators. I mostly care about my own sanity.
 
I don't care aout annoying my neighbors ... they all have loud generators. I mostly care about my own sanity.
HAHAHA - got it! Based on what I've heard during past power outages none of our neighbors have generators, so I don't want to be identified as the only one with power.
 
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I'm on the western edge of all this mess. Very little wind for me and the power only flickered once. We get worse during the typical afternoon thunderstorm.
Good to hear you got through this unharmed! I sure do feel sorry for all who didn't!
 
I'm on the western edge of all this mess. Very little wind for me and the power only flickered once. We get worse during the typical afternoon thunderstorm.
May it be mild until Ida passes completely ☮️

Sounds like the system you’ve built should cover some needs if it’s called upon. ? Good testing.
 
I haven't updated this in a while. Over time I have added, replaced, moved, and removed a few things in our setup, and my wiring is getting a little bit messy. The mess doesn't affect the way anything runs so I don't feel any urgency to shut things down to straighten it out, yet, but it is beginning to bug me. I was planning a cabinet front with doors to hide it all, but the wife kinda likes it like it is so that hasn't progressed.

1000 watts of solar was the biggest addition so now we are up to 1600 watts installed. I have another 600 watts of panels in the shed. Swapped out some fuses and breakers for better. We are very happy with how the system performs and VRM is amazing.

During our summer heat wave we bought a Midea U 12000btu A/C to supplement our central A/C that couldn't keep up. We ran it off of the extra solar just to see if we could and at our current rates we figure we avoided $20 - $25 a month of grid electricity.

Now we are thinking we should add a real solar array, and more batteries, and another inverter so we can run more of the house on solar.
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I really like your system. Small wires like the BMS stuff can be a real pain to keep looking nice..

Some people will use spiral wrap to help tame the nest that can build up over time if the small wires bother you. What is really nice is that you don't have to take anything apart to add it.
 

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