diy solar

diy solar

Bad days for Solar Production.

I ended up pulling about 1 KWH from the grid during the high peak rate because my battery voltage dropped to 50.5 volts, about 45% state of charge, my grid support lower limit. I decided to let it go down another 0.5 volts to 50 volts even, about 40% SoC. Now it is 9:40 pm, back into the Off Peak rate, so I shut down my PLC (it would keep trying to zero the grid power) and I have the grid charging the battery at almost 1 KW. I'll let it go at that rate until the morning and see how the weather is. We might get a little sun peaking through. I can kick the charge rate a bit higher if needed. This is the lowest I have let the battery go since I doubled the capacity almost 2 years ago. 50 volts is still 3.57 volts per cell, so it is well out of any danger still. Had the grid gone down, I have it set to run down to 48 volts, 3.42 per cell, which is less than 15% remaining.
 
GXMnow said:
50 volts is still 3.57 volts per cell, so it is well out of any danger still. Had the grid gone down, I have it set to run down to 48 volts, 3.42 per cell, which is less than 15% remaining.
Click to expand...
My basic mathematical skills tell me that your calculations are off here ?
Edit, unless you have 14 cell batteries ?
 
Yes, my battery bank is 14S. I thought I put that in an early post in this thread as well. The NMC EV cells are good from a low of 3.1 volts fully discharged to 4.2 volts at full absorption. With 14 cells in series, that gives a range of 43.4 volts up to 58.8 volt. That fits within the range of the XW inverter.

I did start with a 6P bank, but I have doubled it 12P so I have 720 amp hours now. Still just 60% of the Chevy Bolt battery. The cells are each rated at 60 amp hours. The second bank is a newer gen. Chevy did not change the rating, but the cells do appear to be more like 62 AH as they are always pulling about 3% more current in both charge and discharge, even though the new bank is on longer cables.

And the sun came out!!!!!! It's 9:25 am and I have 1,800 watts coming in from the Enphase panels. Too bad half the DC array is still in shadow. It's only making 130 watts. I used grid power to charge 11 KWHs into the battery bank overnight. But that only got it up to 53.3 volts, so there is still a long way to go before 100%. And I really doubt I will get there. The forecast is still calling for clouds all day, even now. Took me 10 minutes to get this typed, and the Enphase power is up to 2,100 watts from my 4,800 watts of panels. That is great for 9:35 am

There is one thing I really like about the NMC cells over LFP. The voltage does climb fairly linear with the state of charge, with just a little curve making the slope even faster once it is above 55% SoC. So from voltage alone, I can get an idea, within about 5% of where my SoC really is. Here is an SoC graph showing the curve with both 0.25C charging, and 0.25C discharging. I am always between those 2 lines with less than 0.15C either way.

NMC charge curve.PNG

When these cells do wear out, I probably will end up with LFP cells as I could not permit these in my garage. Which is really funny, since my brother and his wife would park 2 Chevy Bolts with a total of 120 KWHs of these same cells in their garage.
 
So much for Weather forecasts. It is predicted to be rain and socked in clouds the next 4 days. Indeed the morning started out all drizzle and sprinkling. Ah Ha!, I thought, perfect time to do some overall maintenance and upgrades to the PV system.

But after disconnecting all power and starting the rebuild wouldn't you guess it? The darn sun came out and I am not capturing any of it. A waste of sunlight. I have been so used to being solar that instead being completely on the grid is a mental adaptation. It feels odd.
 
Yesterday 0Kwh charge, today I did get 400% higher at 0.4Kwh.

Still at 55% SOC, clouds until Tuesday from the weather forecast.
 
I just checked my So Cal Edison usage for yesterday. I knew the battery had run down and it switched to grid power during the high peak rate time. And ure enough, For the first time in 2 years, I used peak rate power. BUT.... I still won't pay for any of it. When I saw it pulling power, I changed the setting to let my battery run just 0.5 volts lower, so it went back to inverting to cover the loads. The energy import totaled just 0.44 KWHs. In the 2 hours before and after that import, I was exporting my small 60 wats or so. The total for the whole 5 hours of peak rate ended up exporting 0.12 KWHs. Then at 9:30 PM, I set it charging, so yes, I pulled 11 KWHs of cheap time power overnight.

The sun is still spotty today. We did get some decent sun for a bit, but the clouds are getting thicker once again. So the battery only made it up to 55.4 volts so far. On the NCM voltage chart, that looks like 75% SoC. The DC panels have also produced 1.9 KWHs on top of the 12.7 KWHs from the XW-pro. But most of that is from grid power. The Enphase system has only made 6.8 KWHs so far today. I have 3 more hours of production, but the clouds are making sure the solar production won't be anything like it was this morning.
 
After braggin on AZ, here comes the alligator tears from all the folks that live in winter gloom. Solstice day was great, but I wanted to max the batteries because I knew today was a comin'. I probably could have hit 62-25, thu I started dumping when my meager pack hit 100% around 1500. Sunrise/Sunset like 0730/1730, production tails off after 3. Today the rains came. Close to 1/2". The energizer bunny in reverse. 8.3 is the lowest recorded production I've ever had. You can see my needs are around 40KWH/day, so with only 60KWH of battery I will likely be on grid before the sun comes up.
...
And it ain't coming up tomorrow either, probably going to be another abysmal day. I will likely just change my inverter settings to 80% or something and let it simply use what little it gets to charge the batteries.

1703312895149.png
 
I'm glad I have a mix of grid and solar in my shop. ty santa for more extension cords
 
Got 1425 kWh this month so far.
Not horrible but less than expected and about half what I will use.

I really need to get some more panels up I guess.
 
Last edited:
Santa is delivering more panels today but the fog is so thick, I can't see the houses across the street.

Tomorrow is the only day we expect to see any sun. So I am running from the grid to keep batteries as close to full as possible.
 
Nobodybusiness said:
Got 1425 kWh this month so far.
Not horrible but less than expected and about half what I will use.

I really need to get some more panels up I guess.
Click to expand...
Your usage sounds like mine. I have been doing ok for the month but we have been supercharging our Tesla's more than half of the month. Good thing is all my Tesla's have free supercharging for life, so no costs, but the time wasted at the supercharger sucks.
 
You must log in or register to reply here.

Similar threads

L
Sol-Ark solar production issue after upgrade
Replies
1
Views
245
Dhalbmaier
D
B
Is my SMA bugged? Showing random errors but not disconnected. (It is a bug)
Replies
2
Views
347
ko6kL
ko6kL
D
Deye Inverter Generator input limit
Replies
1
Views
731
DIYrich
D
F
Do you own an EV and charge with solar?
Replies
17
Views
724
chrisski
chrisski
Lighthouse Beacon
Solar Pool Pump is Rocking and Rolling
Replies
19
Views
952
WorldwideDave
WorldwideDave

diy solar

diy solar
Back
Top