New garage time!

[Kyle_in_Tex]

JFC I just want to hit hte button. But there's always "one more thing".

I hooked up all the panels in 3 strings of 5 to go to the inverter, I finished the conduit. I got the pv wiring done inside. I think I'm going to start with just 2 inverters in parallel until I get more batteries. And speaking of batteries, I need to finish the battery shelf, and finish building the battery pack.

***Speaking of battery packs, I started but accidently left them in parallel for balance charging for like 2 months, but I didn't take them to 3.65v, when I turned it off they were at 3.3x and now they are at 3.29v. ny chance I've accidently balanced them?

But when I went to hook up the set of rails, I realized that along with 1/2" bolt and lock washer, I got 7/16" nuts. So it was back to HD, and to my non-surprise, they were out of grade 8 1/2" nuts. So I had to grab regular ones. Not the end of the world but still. Over an hour wasted of time I don't have much of.

i need to hook up the inverters to the grid breakers still and make the bus bars for the batteries as well as the cables as well.

When I'm done, I'm going to write a manual on building a solar system volume 1, steps 1-1000. Followed by volume 2, steps 1001-2000, and I suspect I'm up to volume 8 now, but the good news is I can see the light at the end of the tunnel.

Are you talking about whole house backup batteries?

edumacate me

 

[fatjay]

Are you talking about whole house backup batteries?

edumacate me

Yes, this will be an off grid setup. There's 2 types, grid-tie, and off-grid. Grid tie connects to the grid and feeds back into the grid your excess solar production. Off-grid charges batteries.

I have one battery pack, which I'm building now. It's 15kwh and the battery management system is rated at 100a. It's 48v, so the maximum drain on the battery is 4800w.

I have 6 inverters, each rated for 3000w, with a surge of 6000w. So even if I hooked up all of the inverters, I couldn't utilize them because I would hit the maximum discharge of the battery.

I needed power in the garage, and now I have it.

 

[fatjay]

Batteries on charge to top balance, and started the battery room. It'll have room for 6 packs. It's 27" wide, 2x3's going up the wall for the shelves which makes the shelves 24" wide. The packs are 21.5" wide, so I should be good to go.

 

[Kyle_in_Tex]

Ok, I didn't remember you were going off grid. You need something to carry you through the night and cloudy days.

I'm not a fan of batteries. i helped with research projects on many types for years. I know they are useful, and I can't live without them either.

 

[fatjay]

Ok, I didn't remember you were going off grid. You need something to carry you through the night and cloudy days.

I'm not a fan of batteries. i helped with research projects on many types for years. I know they are useful, and I can't live without them either.

Grid tie, permits, inspections, and the tie in fee's are thousands of dollars. Then you can't change anything. And the inverters are more.

I'm using LiFePo4 cells, which have a cycle count of ~8000, so I should be able to get a good 20 years out of them before they start degrading.

Before lifepo4 came along, i agree, battery was't the future, lipo and lithiums aren't safe and I wouldn't have them in my home. They only last around 3000 cycles, which isn't long enough considering the expense. Plus that whole fire thing.

Lifepo4 don't catch fire or explode, have high cycle count. But drawbacks are they're heavier, and have a lower max discharge rate.

 

[fatjay]

I wanted to be there the first time I switched on PV, but I didn't want to lose time. and get some history. I do not get up with the sun, so I flipped it on and hoped I hooked everything up right.

And as it turns out, i did!

And as it turns out, it is the FIRST overcast day in 2 months, we're having an incredible drought.

 

[fatjay]

Working on the battery closet still, not very exciting. Battery is still top balancing.

What is exciting is my ocean ev is charging entirely via solar, as it's a much sunnier day today.

From the charts I've learned a few things. Panels hit their voltage relatively quickly and maintain it consistently. The amperage fluctuates with conditions. Which is relevent when you consider startup and operating voltages of the mppt's. When 3600w of panels hit 42w of power, the voltage was 142v.

The inverter manual says startup voltage is 150v, operating 120v-250v, but it starts doing stuff before that.

 

[fatjay]

So apparently cell compression is super important and relevant to getting the claimed cycles out of the cells. Between 3000-7000 newtons.

So wrapping cells in kapton tape looks like it's not going to be enough. So I reached out to hoover to get some 3/8" aluminum plate and all-thread. I figure if I'm going to do it, I'll do it right. They claim 21 years if I cycle the packs once a day, and i compress them. 7000 newtons is 1573 pounds. 10ft-lb of torque is 1600lb of clamp force, spread across 4 bolts is about 2ft/lb each should be sufficient.

Today's power has been much more consistent than yesterday. Yesterday was all over the place due to clouds.

Yesterday:

Today:

 

[fatjay]

Getting slow progress on the battery shelf. I changed the design a few dozen times, but now I think I have something that will work, and give me 6 spaces for batteries, totaling 90kwh.

I have 10" of space for cells that are 8" tall, so that gives me a little space to deal with things.

 

[murphy1244]

You going to paint these?