My CT clamp is fixed to a consumer unit supply, but I now have a second consumer unit.

So I need to move the CT clamp to the shared live coming out of the smart meter.

It seems like something I should be able to do myself, except that I need to thread the wire through a hole in the wall, too small to feed the clamp through. This means cutting the CT clamp wire, threading, and re-joining (the terminals in the CT clamp have been glued).

Assuming I don't allow the cut wires to short with each other, is this safe to do with the system up and running, or should I shut everything down?

I just picked up a few of these panels used/cheap. They say there is a built in micro inverter and that they output AC, not DC. It looks to me like the micro inverter was removed before I got them(see schematic 2nd photo). I want DC output from the panel to charge a portable power station anyways. Just looking for validation that this is the case.
Also, I got the panels for $20/each. They are about 10-12 years old. The guy had about 5 more. Is it worth it to pick up more? I will be building some off grid structures(house and some farm buildings)in about a year. I'm sure I could use them somewhere, but I wonder if the technology has advanced so far in 10 years that something new would be much better.

The delivery charge is more than 3x the supply!

Much heavier than anticipated 😅

I'm trying to purchase 4 panels. https://a.co/d/06UO7ErZ Amazon says I previously purchased these panels online. They do look the same in the picture. but I'm checking the details I'm seeing some very confusing things.

The description says they are 2 100w monocrystiline panels. But also claims they are model rs-m250. But rs-m250 is obviously a very different panel (one 250w bifacial panel) when I Google it.

I'm concerned because I'm trying to match my current panels. I already have four rs-m100 that are all the same specs. Here's a picture of one of the panels I have. And a picture of Amazon panels that confuse me in case the link is trouble.

I'm thinking y'all seen these things before. Maybe I'm missing something obvious? Thank you. 👍

PS: I don't need different panels. Humbly, I don't want different panels. I'm just trying to get the same panels I got last time.

I'm building a small test setup that consists of one 100Ah LiFePo4 battery with built-in BMS ( no access to communication ports), cheap "hybrid" inverter, Victron Smart Solar charge controller ( 100/30 ), Victron Smart Shunt ( set as a battery monitor) and RaspberryPi with Venus OS 3.72 acting as a "CerboGX" device. Victron charge controller and smart shunt are connected to the Pi via V.E. Direct ports - bidirectional communication works without issues.

All good and working except one thing - DVCC. My goal is to limit battery charging current to 30A ( combined current from the inverter and charge controller). My understanding was - if a smart shunt detects combined charging current higher than ,let's say, 30A, DVCC would lower Victron charger's current to keep the changing at 30A max.

But it's not working. No matter what limit I set in the DVCC, Victron's charger is charging at its max current set in its settings while charging current measured by smart shunt exceeds the set DVCC limit by a lot. VenusOS says the charge controller is networked and in external control. Everything looks ok but it's not working as I thought it would.

My plan B is to do this in Node Red on the Pi but I'd like to avoid that if possible. Could anyone share any advice on how to troubleshoot ( I have a SSH access to VenusOS )? Thank you!

I realized after reading the responses to my post yesterday that I needed to do quite a bit more research and that this isn't something I can just throw together. I've fine tuned my diagram to show more specifics, and taken into account much of what was suggested. Would love a final pair of eyes before I pull the trigger.

Here's the rundown:

Current Wire Size and Fuse Plan

Solar Panel → MPPT AND MPPT → Bus Bars

Wire Size: 10 AWG
Fuse Size: 20A

Reasoning

• 10 AWG is capable of safely handling this current range with good voltage drop characteristics for the short runs I'm expecting.
• A 20A fuse protects the wire and also provides a convenient disconnect point for if I ever feel the need to service something.

Calcs (that's short for calculations btw)

Solar Panel Side

• Panel isc is 9A
• NEC 125% safety factor: 9A×1.25=11.25A

MPPT Output Side

• MPPT max output current: 15A
• Applying 125% factor: 15A×1.25=18.75A

So a 20A fuse and 10 AWG wiring should be enough on both sides.

Bus Bars → Batteries AND Bus Bars → Inverter

Wire Size: 8 AWG
Fuse Size: 30A

Reasoning

• 8 AWG provides lower voltage drop and additional overhead compared to 10 AWG.
• 30A fuse protects the wiring while remaining above expected operating current.

Inverter Calc

Expected maximum DC current draw from the inverter: 500W/24V × 1.25 ≈ 26A

So the inverter should draw approximately 26A maximum under full load including safety margin.

Battery Considerations

Thermal Safety (Unsure if this matters as much as I think it does)

The LiFePO4 batteries are rated somewhere between 0.5 - 1C continuous discharge from what I could find. Couldn't find the specifics for the batteries I have so assuming 1C.

Approximate continuous discharge capability at 1C with 2 batteries in parallel:

• Total continuous capability becomes approximately 51A
• The inverter load should split roughly evenly between batteries

Expected load per battery: 26A \ 2 ≈ 13A

So each battery would only be supplying about 13A under maximum inverter load, which is comfortably below the 8AWG rating of 40A.

Capacity Considerations

Daily Power Use

I'm assuming at worst a constant load around 25W although I'd expect much much less: 25W × 24 hours = 600Wh/day

Occasional higher load of ~75W when I'm charging a 20v battery and/or have a light on: 75W × 2 hours = 150Wh

So most days: ~600Wh/day Occasional heavier day: ~750Wh/day

Solar Production

With one 255W panel (Let's assume I'll only get 200W since it's an older panel) and ~4.5 average sun hours: 200W × 4.5 = 900Wh/day theoretical

After real-world losses from heat, MPPT conversion, wiring, panel angle, clouds, etc, I'm asuming about 80% usable: ~720Wh/day usable

So one panel should usually cover my ~600Wh/day load, and come close on the heavier days which would only come every 2 weeks or so.

Future Expansion Considerations

Adding a Second 255W Solar Panel

If I add a second nearly identical 255W panel with the same 9A isc, it looks like i'd be better off putting them in series.

The current stays the same while volts double: 9A × 1.25 = 11.25A

So the existing 10 AWG wire and 20A fuse/breaker should still be acceptable.

Cold Weather Voltage Check

Panel specifications:

• VOC at STC: 37.4V
• Temperature coefficient: -0.34% per °C (Got this from a spec sheet i found)
• Lowest expected temperature: -30°C (This has maybe happened twice since I've lived here)

I used a calculator here and got 44.39V per panel in a series.

So even at approximately -30°C (Which will never happen, except for maybe wind chill), two panels in series should remain below the MPPT’s 100V max.

Expanding Battery Bank to Four Batteries

If I add two more identical batteries:

• Total capacity: 25.6V/102.4Ah
• Total energy: ~2,621Wh

At an assumed 1C continuous discharge rating: 25.6A × 4 = 102.4A

So the full battery bank could theoretically supply ~102A continuously and with the same 500W inverter i'd get ≈26A

And an expected load per battery of 6.5A (26A / 4) so my fuses/wiring should be fine if my assumptions are correct.

Things I'm still unsure about

• Do I need to add MRBF fuses to the batteries? I don't see battery fuses in many diagrams on here, but it seems to be suggested in a few other places I've looked.
• The Victron 24|500 inverter manual talks about connecting the inverter neutral output to the chassis/ground. I doubt I need to worry about changing that since this is off-grid.

Closing thoughts

This was all quite a bit to get the hang of today but I definitely understand a bit more than I did yesterday. And if in the future some random person wants to put a few lights and a charger in their off-grid shed instead of running power from their house, I hope some of this helps. I'll try to come back and edit in what I bought and how it ended up working if/when I get to that point. Thanks for everyone's help and input.

Hello, I need some suggestion,

I ordered 2x585 watt bi facial topcon panels. One of them had this, looks like a solder blob under the sheet around 2 mm² or less.

It is the underside of the panel and not in the main top face.

Is it ok? Or should I really return this?

Getting a replacement of the same brand ("Waree energies") may take almost a month to arrive.

I wanted to mount around 700 watt plung and play system on this balcony.

Don't see how I can do it safely, as I can't access the bottom outside. Any suggestions?

someone gave me this old looking panel, and it pushes out 18V in full sunlight unloaded, but i do not know how to discern the wattage and this thing has no label. toss? or hope for use?, if hope for use, how do i figure out the watt capacity of this thing?