First Post, First DIY Solar System - on the cheap!

[Hardware99]

Good Morning/Afternoon/evening (depending on when someone reads this )
I've wanted to get into solar for at least a couple of decades. I was following the tech when ARCO Solar and Solarex were doing booming business in the 90's.

I finally got to the point of getting my system together here in the Kansas City Area. Kudos to Will Prowse and his YouTube channel because that's what got me going again. His review of the EG4 product line really sold me on using an off-grid AIO for my home. A month ago, I was in the hospital when a storm blew through the Kansas City area and we lost power for a bit over 2 days. This just reinforced the need for automatic stand-by power to keep the important stuff going (if it can reduce the utility bill a bit in the process, that's just a bonus).

I don't have a lot of disposable cash, so this had to be built on the cheap, over time (but capable). Enter the EG4 3000EHV-48. There is no way I can run most of my house due to limited panel space on the roof, but a supplement and stand-by power when the utility is down is the way to go for me. This is for my critical loads panel: refrigerator, lights, the furnace, and internet/tv.

Panels that I bought were used 250w Trina Solar - got them in great condition for $83 shipped (a friend and I did a combined buy of 18 - 10 for him, 8 for me)

Batteries were a different subject all together. I didn't have the few thousand dollars for a reasonable amount of LiFePO4 battery storage. I've done a lot of research concerning DIY power walls and went with a 48v, 18650-based battery of my own construction using 1050 cells in a 14s75p configuration. Purchasing new surplus cells over time, l tested all cells at 1A for capacity and temperature (that took a serious amount of time), and with cell-level fusing, creating a 12.5kWh battery bank that can handle up to 75A charge/discharge without issue. Getting ready to get them spot-welded and a JBD BMS to bring it together. Tested and fused, the max draw is 63A and max charge is 80A from the EG4 3000EHV, so well within the cell testing parameters to help prevent overheating, etc.

I'm at a point in my life where going out into the cold to pull-start a 5kW gasoline generator just isn't healthy and dropping $6K-$10K for a whole-home generator just isn't worth it. Gas for run-time gets expensive and nobody will tell you that either.

I look forward to posting pictures when it all comes together.

-Patrick

 

[drps10]

Good luck and following.

 

[Adam De Lay]

Gas for run-time gets expensive and nobody will tell you that either.

That was one of the big things that pushed me towards Solar. I was initially looking at a whole house backup generator and then I saw the price and realized it would sit in the yard for most of the year “in case I needed it” and then you would STILL have to pay for fuel.

Solar gives you the ability to save money on a daily basis…

 

[Hardware99]

Don't forget the maintenance required for that generator. All the 'extras' that really turn out to be required. I was floored by how much an installed 12-15kW NG home generator costs here. 6k-12k based on size, mfgr, etc. That's a lot of cash outlaid for expected limited runtime.

(no official hardware to put in my Sig line, yet. LOL)

 

[50ShadesOfDirt]

I don't want to derail any of your solar journey, so don't take these generator comments as anything other than "more info" for you, on the generator side of things!

Whole-home standby generators (let's say "generac", for example) are indeed "a solution" for someone wanting backup power if in grid-down scenario. After purchase and installation, usually by an authorized dealer, you'll end up with an automatic backup to loss of grid. Grid goes down, gen comes up; grid comes back online, gen goes down. For short, hours-long duration of grid outage, everything just works.

About $5k for purchase (depending on model), and about $5k for installation of everything needed, for a typical home. Annual service costs, expensive to repair, etc.

What is the alternative to this? A $1k Westinghouse wgen9500df (propane) generator, which are "automatic-choke, remote-start" with "smart" port (supports a westinghouse ATS transfer switch). Add this to your home, sits outside next to a 100-lb propane tank, and your electrician can wire it into a port to feed power into the house (many options here, so discuss w/ electrician). You point your fob at it, and start/stop it. If grid goes down, you are up and running in seconds, and can throw some critical devices over to the plugs running off of generator.

If the fob remote start/stop isn't enough for you, you can add in westinghouse's "smart-ATS" box, which when plugged up together with the gen, will sense that grid power has dropped, and the ATS box will start the gen. When grid comes back up, the ATS box will stop the gen. Also very automatic, just very inexpensive compared to a whole-house gen setup.

Many folks build a little noise-box shed around such a portable gen, to the point where you can hardly hear it at all ... many YT vids about this.

Hope this helps ...

 

[Hardware99]

That’s good info there and I’m sure that many might take that route. Given my suburban location and corner lot layout, I really don’t have much in the way of a ‘back yard’ where I could place something like this.

I have space on my garage for about 9-250w panels (unobstructed for about 110-120 degrees of arc) and a section of my house for another 8 or so (with 60-70 degrees unobstructed), so solar is where I wanted this to go. Good ‘used’ panels are out there at a great price too.

I really enjoy doing things myself, whether it is my own plumbing, electrical, vehicle maintenance, etc. I love to learn. Always learn more than ‘just what you need’ too (this means Follow Code! Be safe)

In this case, my upcoming system is a supplement to my existing grid - Solar/Utility/Battery. Solar to keep the batteries topped off and ease grid usage during the day. If all goes well, I may look at SBU if supply/demand curve on my critical loads panel allows.

My truly limiting factor is my battery bank. It is (will be? In-progress still) an 18650-based powerwall at 12.5kWh. At an assembled price of $103/kWh, its a good deal but not without downsides/risks. Thats why I only have an EG4 3k AIO.

Really looking forward to the day I can ‘throw the switch’ and watch it hum (as it were)

-Patrick

 

[OffGridInTheCity]

Batteries were a different subject all together. I didn't have the few thousand dollars for a reasonable amount of LiFePO4 battery storage. I've done a lot of research concerning DIY power walls and went with a 48v, 18650-based battery of my own construction using 1050 cells in a 14s75p configuration. Purchasing new surplus cells over time, l tested all cells at 1A for capacity and temperature (that took a serious amount of time), and with cell-level fusing, creating a 12.5kWh battery bank that can handle up to 75A charge/discharge without issue. Getting ready to get them spot-welded and a JBD BMS to bring it together. Tested and fused, the max draw is 63A and max charge is 80A from the EG4 3000EHV, so well within the cell testing parameters to help prevent overheating, etc.

LifePo4 is the default choice these days and a good one for sure - but 6 years ago it wasn't as prevalent and I went 2nd hand 18650.

I started my journey 6 years ago with a 7s50p (24v) 18650 battery and over the years it's grown to a substantial (121kwh / 48v) battery bank made up of 9 x 14s100p 18650 cells. In the process of building 2 more for a grand total of 148kwh - and I think that will be it. Agree - cell level fusing is good protection and low stress (moderate voltage range, lower ma/cell, moderate ambient temps) = long life.

Here's an updated table of the 9 x batteries since 2018 as of yesterday and you can see the cycle history. The newest batteries are just a few hundred cycles and oldest battery at 1,752 cycles is not showing any degradation.


To be encouraging... I can see many more years using this 18650 powerwall for my solar system.

 

[Hardware99]

It’s nice to know that others still do 18650-based storage. Makes me feel a bit better about going that route. That is an INSANE amount of 18650’s to test/assemble ?. I did notice that all your packs are at the same AH rating, which should be good for balanced charging across them.

Where do you keep that much power stored? Outbuilding comes to mind in case if some critical failure. My cells are surplus unused stock, so insulators/cell wraps, then onto the charger/tester @1Amp. As long as I keep my charge/discharge at or below 1A/cell (14s75p in my case) I’m not much worried about a meltdown.

-Patrick

 

[OffGridInTheCity]

It’s nice to know that others still do 18650-based storage. Makes me feel a bit better about going that route. That is an INSANE amount of 18650’s to test/assemble ?.

For sure - it's a background activity (hobby) I do in my office while listening to youtubes. Not difficult but does take a bit of time. Battery #10 (green cells) is underway....

I did notice that all your packs are at the same AH rating, which should be good for balanced charging across them.

Yes, they balance very well. I do touch-up balance once every 6-9 months but don't do any balance in-between. Batrium BMS makes this easy to monitor/manage. Normal to run a 40mv - 60mv max difference thru a cycle but at 3.5v - 4.0v it doesn't matter as long as it's consistent day to day. The 1st battery (with 1,752 cycles) is the 14 blue bars to the left and the latest battery (183 cycles) is the 14 blue bars to the right. You'll see that the oldest one stays balanced with the newest one on it's own - which is why I conclude 'no visible degradation yet'.

Where do you keep that much power stored? Outbuilding comes to mind in case if some critical failure. My cells are surplus unused stock, so insulators/cell wraps, then onto the charger/tester @1Amp. As long as I keep my charge/discharge at or below 1A/cell (14s75p in my case) I’m not much worried about a meltdown.

-Patrick

The solar 'area' is under a corner of the house w/mild year-round ambient temps. With good monitoring, low-stress operations, and emergency shunt-trip I don't worry.