Adding storage to my Enphase system

[Hedges]

I'm interested in that storage funding for my Sister.
The system would have 32kWh BYD HVM battery ($18k) in addition to SBSE. (Originally thinking 7.7kW, now have reservation for 7.7kW + 3.8kW SB with intention to substitute one 11.5kW SBSE when that's released Q2024.)

Having $24k of funding would cover the system nicely.

Good to hear (as a beneficiary not a taxpayer) that a stupid CPAP which could be powered by a solar generator could justify whole house backup/offgrid system.

 

[Ampster]

If SCE ever questions me, I will say I only added a backup UPS, I didn't know it was pushing any power to the grid.

That is a good strategy, and one I am relying on. I found a PG&E document that explicitly allows backup as long as it is behind a "break before make" switch. I have not added that switch yet because it was not on my permitted plans with my County. But if ever questioned, I can easily install the switch. It would be useful as well if I ever needed to take the SolArk offline for maintenance.

 

[Ampster]

I'm interested in that storage funding for my Sister.

As far as I can tell, very few individuals have applied and gone through the application process. Some solar companies are very adept at doing that because they can make a profit. PG&E advertised it as if it is their program but it started with the CEC and there may be more future funding beyond the equity resilience amount that still exists..

 

[GXMnow]

Back on Sunday, May 12th, I left it exporting close to 3,000 watts, and sort of forgot about it until 6 pm, oops. Here is what the XW battery summary looked like.

While the sun was still shining, the battery was charging nicely. But from 4 pm to 5 pm the sun fell enough that the demand from the XW to keep the export going starting pulling more from the battery at the same time the DC system was not pushing as much into the battery. SO the battery went from charging to discharging. After 5 pm, the slope starts getting steeper as the current ramped to more than 50 amps. At that point I powered up the PLC and let it start controlling the export to match my loads. Back to 10-20 amps of discharge. That extra volt I pulled out of the battery showed as the battery ended the day a volt below where it started. I "used" more out of the battery than I put in on this day. Here is what it looked like at So Cal Edison.

From 3 pm to 6 pm the XW did as asked and kept my export at 3,000 watts. I have a few small loads in my main panel still, so that explains the slightly less exported numbers. And yes, this is now my record most power exported in a day. And 6 KWHs of it was at the higher rate.

The next day started out a bit overcast. I was a little nervous it might not keep up. And I had to work, so I was not here to monitor it. I left the PLC doing it's job. It took a little longer to top up the battery, but it still did it with energy to spare and the Victron again went to float.

After seeing this, I am going to spend a bit more time and get the code in the PLC to add the Export from DC routine. It is a shame to waste 3 to 5 KWHs every day as the system sits in float. Even if it is all at my cheapest rate, it is at least another dollar a day in credit.

 

[GXMnow]

Amazon managed to send the correct 16S version of the 100 Balance 1 amp active balancer. And today, I got my extra connectors to make up a "Y" harness. I tested it all by letting it finish balancing my E-Bike batteries. You can set them to balance less than the number of cells they come wired for, BUT.... You still need to connect the highest cell lead to the most positive. And it only stays on for about 1 minute each time until you get it set to the new lower number of cells, and then reboot it. It's a little pain, but I wanted a 16S for when I do LFP cells. The online data makes it sound like it will just work with 8S to 16S with no hassle. But in hind site, I should have just bought a 14S. But I got it working, and I can easily switch it back to 16S mode if needed.

It took most of a day, but it did balance my E-Bike batteries to under 0.02 volts difference from highest to lowest cell. Not bad at all. It stops when all cells are within that 0.02 volts, it won't try to go closer.

So I took one half of the new battery box off line and connected the 100 balance board to it. Oops, the JST connectors are a little different. The side on the cells plugs in just fine, but the side to go back in the BMS is a little too thick and won't go in. I'll have to file it down a little. But for now, I can still open the app and watch it balance the cells. Hmmm. It's not turning on, the LED is just a dim green. Did I wire something wrong? Oh good, the app connected. Here is the monitor screen.


Hmmm, now I see the problem. My newer set of Chevy Bolt cells are balanced to where the highest and lowest cells ar just 0.007 volts apart. The app even flipped to show 0.006 as it froze the screen shot. This balancer won't even try to pull them any closer. Okay, I'll move it to the other half of the battery bank. Plug the upper BMS back in, switch that battery on, and switch off the lower battery. Same issue, my "Y" cable won't fit in the BMS. So once again, I am just connected to the cells. Here is the balancer app on the second half of the cells.


Not quite as tight of a balance at 0.010 volts difference, but that is still half of what it will even try to balance out. So as I pretty much expected, my LG Chevy Bolt cells are very well behaved, and it seems the little 0.060 amp passive balancing is enough for them. I will get the correct hood an get my "Y" cable working properly so I can monitor the cells when I need to. The "Y" cable does work just fine on the E-Bike batteries and BMS units. Those packs need it way more. Hopefully I will actually be able to go for a ride on Sat. I already know I am working Sunday.

 

[400bird]

What are you using for balance wiring? The circuit board built into the factory pack has 5/8 amp fuses.

 

[GXMnow]

I used the 20 or 22 awg wires that came with the BMS, had to extend a few of them. I soldered them directly on the tabs where each bus bar soldered to the PCB. While trying to cut the pack down to make the 14S stack, I popped several of the factory fuses as the saw went through the PCB. The fuses are still all intact on my original module, but I didn't have the connectors when I built that one. And with the 2 amp JK-BMS balancing, I also soldered onto the bus bar tabs. On the new module, I did not bother with any fusing. It is a single battery string to a single BMS. But on my old battery, I wired the 2 strings in parallel to a single BMS. I have the balance leads monitoring both strings. I put 5 amps fuses on all 15 leads from both strings. Yes, 30 fuses. What a pain that was. If the 2 strings went way out of balance for any reason, I wanted fuses to pop instead of a bunch of 20 AWG wire burning up.

I am still totally impressed at how well all of these Chevy Bolt cells are staying balanced. I truly expected the new bank to at least have some drift. When I measured them by hand a few months back, I was pretty sure I saw a few cells about 30-50 mv out. Did the Daly 60 ma balancing fix it, or was it a bad measurement? Since I added the Victron charge controller, and with decent sunny weather, the system has been held in Float a lot more, and that does give the Daly passive balancing a lot more time to do it's job.

I'm glad I didn't waste a bunch of money and get 2 more JK-BMS units. The "100 Balance" active balancer was $40 and I already got my money's worth out of it balancing up my E-Bike batteries. It took it about 2 days to get the from horribly out of balance to dead on within 20 mv. I can plug it into the battey after every few rides to check on them and take care of any balance drift.