Yes, I think it might be better to just purchase the 250V version of the LV6548 and install the EG4 500V charge controller if you want higher VOC and that extra 2% yield (which you could just add more panels). I'll eventually test the 8S against two 4S parallel strings just to see real world results. With the 2 MPPT's per LV6548, might be best to just fully use them.
This is what you're doing as a test, right? Depending on how well it works, I may have to consider this as another option. I'd still have to rewire my panels to get rid of the clipping, but maybe. Sure would save a lot of money. How would that look on a wiring diagram?
I just run PV to SCC and SCC to the Victron distributor.
Ian had a deal too with no support and warranty was thru MPP. Right now though he sells a pair at $2099 with full support and 2 year warranty. I'm thinking of buying spares.
For strings that are close to the inverters, use the MPPT's on those. For the higher voltage strings farther away, use the EG4 SCC's.
All of mine are 100 ft or more away. Because I was a dummy and configured them 4s2p I ended up with max amps of 21.6 so when it clips at 17a I'm losing a lot. I'm averaging around 2400-2500w per string, Even with the clipping it should be closer to 2800w but I think that's because when it ramps up the amps drop even more, down to around 14a to 15a. I believe that's due to the distance.For strings that are close to the inverters, use the MPPT's on those. For the higher voltage strings farther away, use the EG4 SCC's.
How much are you clipping and for what length of time thru the day? The 6500EX's clipped and capped input at 3.9Kw and not the 4.0Kw they advertised. 100W times 5 hours times 2 inverters is 1Kwh per day. How long to get the $$'s back for the SCC? At $0.20 it would take just under 7 years.
If it comes to 2 Kwh per day, then less than 3.5 years.
I have a sheet of 3/4" plywood screwed to the wall studs. An old habit from how we mounted stuff in radio tower buildings. It's not going anywhere.
There was a time I could carry a sheet of 4 X 8ft 3/4 inch plywood and fasten it to a wall or up a ladder to the roof by myself. Now I have trouble with a 4 X 8ft sheet of foam board.
I'll size up a particular task and my brain says "I can do that!" My 62 year old body just laughs...
Same here. Not sure where I learned that. Seems like I've always done it.
Wire cost money. In my case, the cost for wire was another $600. The EG4 SCC's were $400 each but I did need to add some battery cable and I also decided on a junction box with busbars to connect both SCC's together before heading to the Victron Lynx busbars. The latter wasn't needed, I could have just ran 4AWG battery cable to the Lynx from each unit.A lot of rookie mistakes but fortunately I didn't overdo the voltage so at least I got that right. I know better now so it's a matter of figuring out the best way to maximize what I have. The panels are on the shop roof with a pretty shallow grade and I've almost filled it up on the south facing side. I could get one more string of four panels. Or I could put more on the north side and still get decent production in summer and at least something in winter. But the thing is, if I can reconfigure what I have and get closer to the max capacity I don't think I need more panels. Ergo trying to figure out if I want to upgrade the inverters or do something else. Getting those strings all to 8s would eliminate a lot of issues and give me closer to your numbers - my panels are 445w and 455w. If I do have to add more panels it means pulling more wire in the conduit between the shop and the garage. I can probably do it but I'd just as soon not. Pulling wires in conduit that already has a bunch of wires is one of the few "not fun" things.
Your numbers make sense on the surface, but I'm not having to use the grid at all unless it's really rainy and cloudy for multiple days. (Okay, I did run the chargeverter yesterday when it was cloudy just to try it out and it rocks.) Also, the coop here dropped the rate back down to $0.11 so there's that. On the other hand, if I was getting full production I'd probably move the last A/C over which would save me maybe $40 a month during the hot and cold months. So the payback in my case would be quite a bit longer.
What you are describing is not only clipping but power loss due to wire resistance may be affecting the yield. Double the amps and power loss increases exponential. Hedges and I had some discussion about this way back. https://diysolarforum.com/threads/how-long-should-wire-be.41580/post-589561
I have been doing it the same way at my power corner. Plywood with tile underlayment on top. Works great for moving things around.
You have run into the "last 10% or 20%" problem. That last 10% or 20% can become costly to capture and use, the returns diminish greatly compared to the first 80% to 90%.
I have had the diminishing returns conversation with the wife multiple times. She still says buy two more racks of batteries or I may be facing some other form of diminishing returns. The gal likes her solar, yup. I'm gonna hold out and just get one more rack because, well, hell, I'm the boss around here.
Man, you guys get into the weeds on this stuff, but I'm glad you do. Mostly.
I've been watching. It looks like they may have solved the feeding back to grid issue with a firmware update. We'll see. I'm pretty sure I'm not doing anything until this fall at the earliest, and maybe next spring. If it's the 18kpv I want to see some more track record. If it's something else - well, I haven't found a something else yet that really gets me fired up. Who knows, it may end up being four of the SCCs. I feel fortunate that I'm in a place where my system works well enough that I can wait.
