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That AGM is inherently safer. With excessive over-charging, they can outgas hydrogen. I don't think that is normally an issue. Vent probably helps, and battery temperature sensor should detect, but maybe not if just one battery is experiencing it. 12 or 16 is OK. (I saw the 4 of another color...

Neutral is bonded to ground at first disconnect after utility meter. No backfeed or shock hazard. On L1 and L2 there would be the potential to backfeed. All my inverters (except an offgrid StatPower) have UL-1741 anti-islanding so are designed and listed to disconnect when grid goes down. I...

Except, a tracker doesn't take up any more space than just adding more panels. /..../..../..../ vs. /\/\/\/\ The rows of tracker have to be spread enough to not shade each other. They don't capture any more sun than the area you've got, except or maybe the lasts row if it casts a shadow...

Exterior lighting can be a big drain. That's one of the things I need to turn off to get through the night on 14kWh usable. All the old inefficient refrigerators and freezers would be another. Is this just about money? How much are you charged for usage? Price out the solutions under...

Mobile systems isolate neutral from shore power, and locally bond N to G. Some grid systems in places like Japan use a 3-pole RCD to isolate everything. In the US, grid + backup, I keep neutral (and ground) connected all the time, and use the N-G bond in my main panel at utility meter. I've...

No. Is there a grant? What's it worth? Does it involve allowing PG&E into my shorts? I have approval for about 15kW of GT PV (2x Sunny Boy with REC, will have Tigo RSD), haven't pulled the permit yet but getting close. Because I've got 3x SBS 5.0 and 2x LG RESU-10H, thinking of connecting two...

Sure, I used my Fluke with 10A range to measure current from 480VDC 7A string of PV panels. No problem, right? Well, they were connected to the input capacitor of my inverter. Blew the 11A 1000V fuse. Another time I connected an inverter with 480VDC on its capacitors to another inverter...

That's 28A imbalance, not necessarily 28A total on one leg. But to avoid overloading and having the transformer cut out, 28A per leg it is. So your idea is a separate, higher wattage 110V inverter? Your original idea was 2x 5kW inverters, 10kW total, which would be 40A at 240V, 80A at 120V...

"I have (12) Fiamm 12flx500 135Ah AGM batteries" I think that makes it much safer in terms of fire hazard.

With inverter disconnected, I think the optimizers put out 1V each. So voltmeter would reveal configuration. But I think they may also support parallel strings of different length. Check the manual. I only have a little familiarity with it from reading. Do you have a monitor that shows...

The currents would add if current split equally, which it may not. You can try to wire with equal resistance path to each which will help. If one disconnects due to over-current or any other reason, then you would get cascading disconnects. You should be able to count on some, but don't push...

Could be, you'll know as soon as you power it up and check with DMM. Can power up with low voltage secondary of another transformer, when you're not sure what winding is what, to avoid over-voltage. (Now where did I put my Variac??) If 2:1, you can wire primary and secondary in series as...

I think Sunny Island is primarily an off-grid inverter for AC coupling and use with a generator. But also has UL-1741 anti-islanding and backfeeding the grid, with a kludge of DC coupled PV pushing battery voltage higher than it wants. At this point, SMA might sell them as backup to US on-grid...

Hmm, I guess I should care about this because it seems I own more dollar value of tracker than PV. As stock, that is. My Flextronics stock spun off about 25% of its value as Nextracker Inc. I guess they were building this stuff. Also assembling panels in the US. https://www.nextracker.com/ Too...

https://global.abb/group/en

That should be 2/3 of the way through anticipated cycle life. A PowerPro would have cost you $0.075/kWh at that point. (Assuming one 100% cycle per day.)

I figure export under the cover of night would be suspicious with basic NEM. I tried to start a battery system reservation for my new place, which has NEM 2.0 reservation but not installed yet. The PG&E web page said I couldn't do that with the PV reservation outstanding, to call. Which I...

For 20 kWh of daily usage, 13 kWh should be just about right for the night. On grid, so OK if a little over or under. The HV batteries from BYD (used with SMA inverters) cost about 2x what 48V server rack or PowerPro batteries do. I'd be interested in lower cost HV alternatives. Or what DIY...

It should support some number of additional panels in series (I think total of 30 or so), and I think 2 strings in parallel - do you have 20s2p array? I would think 50% increase, added 5kW, would fit its voltage and power limits pretty well.

Oops, I knew I had said "Current Transformers" earlier, but turns out I didn't also say "CT" the time. They snap around a wire, measure the AC current. Together with voltage it shows power flow, both watts and direction (import vs. export). Because they work off magnetic field, you could run a...

The way I make higher AC amps is wire a transformer as either isolation or auto-transformer, use a breaker (fuse in your case) to short out the LV secondary windings, connect primary in series with resistive load. 480V windings in series with 120V windings delivers 5x current through device...

For our small systems, I think single point grounding is best to avoid damage from such ground currents. But if you have a distributed system (power to another building), problem with that could be voltage between the earth/pipes you're in touch with and electrical equipment chassis. What I...

You can probably put about 15kW (STC) of panels on a 10kW inverter with little to no clipping. If two strings of different orientations, maybe 20kW (STC) of panels. You can generally parallel multiple GT PV inverters. They may work OK with multiple PowerWalls, I'm less familiar with how they...

It looks like inverter is only 120V, while source is 120/240V split-phase. Panel 1 is 120V only, panel 2 is split-phase, but not clear whether inverter can supply panel 2. It is OK to have inverter back up single-phase panel 1. Generally not OK to feed 120V only into a 120/240V split-phase...

For AC coupling, it takes a couple of seconds to shift frequency and curtail production. For Sunny Island, SMA recommends 100Ah of 48V battery per kW of AC coupled GT PV (e.g. Sunny Boy). I'm using AGM, which can accept a high charge current, and have maybe 30% the recommended size. It should...

Fairly readable. "A scheme for blocking DC in transformer neutrals was developed, and a pilot was installed. However, the need for such a scheme may be diminished because Hydro-Québec also installed series compensation capacitors in most of the long lines in the 735-kV network." Capacitors...

That doesn't take much imagination in my case. Just wistful memories of slightly better times.

I think what you want is something like Powerwall - without backup. https://www.tesla.com/support/energy/powerwall/learn/how-powerwall-works Any of the hybrids that support CT targeting zero export should also do that. And easily provide a backup panel - if you have alarm or monitoring...

I of course approve of your excellent taste in inverters. What does the 70kw(h) consist of? Are you doing grid-tie net metering, or offgrid? I don't think the Sunny Boy -40 inverters have the latest required grid-interactive functions that the (now discontinued) -41 models do. If on-grid, 2x...

Possibly the most cost effective would be to overproduce, making 700% of daily use. Then that 15% credit is enough to cover the time when you're not producing. PV panels are cheap. DIY GT PV might cost $1/W, and amortize to $0.025/kWh over 20 years. Making 7kWh for every 1 kWh you actually...

Are you saying that transformers for high voltage transmission use Y configuration for both the secondary step-up driving the line and primary of step-down being driven? Unlike Y secondary and Delta primary for most low-voltage applications? Because it needs to drain off high voltage low current...

Well, it was just lower tech. And that Event is named after the guy who detected it. https://www.livescience.com/space/the-sun/see-the-monster-sunspot-that-launched-the-carrington-event-the-most-devastating-solar-storm-in-recorded-history

Does "DDT" (throwback to CP/M) not exist any more? Or, does the programmer take an encrypted file, and that name is not plain text in the source file? Or checksum prevents diddling? (just technical curiosity. I would like to see more extensive plagiarism protection in hardware/firmware products.)

By "Twist" I mean they have insulators holding the three phases (often in a physical Delta arrangement), and as you drive down the road you will observe they periodically change places. That is, the 3 wires are "twisted". So they form a loop, and EM wave or magnetic field induces a voltage in...