Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Remotely turn on/off solar
#11
Aliexpress SSR 40A is inside max rated for 6A so no wonder they are 10% the price!! Youtube it and you find many videos of it Tongue

The 3phase AC rated contactors we use are also DC rated. Never use AC rated that arent DC rated.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
#12
(01-07-2019, 08:15 PM)completelycharged Wrote: Use one of these :
https://www.aliexpress.com/item/SSR-40a-...55841.html

No, dont use one of those.
Reply
#13
150V 100A power board £25 - just a few more FET's in parallel, it's only the same principal that inverters use to pulse switch on/off the DC inside.
https://www.aliexpress.com/item/147S-Lit...52304.html

The china SSR's are heavily impacted by inadequate cooling as it is depends on the actual FET inside and the degredation at higher temperature operation. The SSR's have to be mounted on a heatsink, otherwise 6A may well heat them up to the point of failure just like any ordinary cheap FET with a high gate resistance.
Reply
#14
I have blown up MANY and picked many appart and none of them work as a proper SSR do. Everyone have had crap components.
Note that they dont even get warm before they are blown... They just let the magic smoke up loooong before that. The last 25A i picked apart blew at a load of massive 1000W resistive load and you couldnt feel any heat Tongue

That powerboard have 10x the capability than the cheap SSR do have Big Grin

The funny part is that I have picked apart China ssr with same mosfet in the 25A version such as the 40A version.

You might find SSRs that do work but yet I have not found that. I generally buy 40A version and then at most drive a couple of Ampere through it and it seem to hold ok.
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
#15
https://www.youtube.com/watch?v=qnPbTjfyX8E
The SSR he tore appart was 25A rated and the FET inside (BTA166600B) is only rated 16A RMS continuous.

As to the build quality at 09:32 into the video the two comments of :
"nothing that jumps out screaming one of these is a counterfit"
"and theres nothing that screams out that this one is a piece of grabage" - basically just usual name plate over rating

As to failure mode, the current spikes in DC can be very severe with large battery packs and blow SSR's quite easily, especially when switching anything connected to a battery pack that contains a capacitor as the surge can easily be well over the maximum FET short term current rating.

1000W at 48V = approx 20A and could have just been over the FET "china special over rated" rating for a 25A SSR...

As per all nearly chinese equipment, never buy and us it at it's rated current as they seem to always over rate almost "everything".

As to using FET's for any form of isolation, NEVER as they usually fail short unless you have a high enough fault current then they blow open, litterally in most cases.

Using FET's for battery charge protection on solar is bad if it is the only mans of over voltage protection because the solar will usually result in a short failure mode (due to the lack of a high enough current to blow an open circuit failure) and your battey could then easily over charge is this switching was the only means of over charge protection.
Reply
#16
One of the SSR 40A from china i ripped apart had a mosfet rated 6A RMS on typical useage. Unfortunately I dont know the part number of it more ethan the 6A continues rating. Secondly it did not have proper contact with the case of the SSR either.

So its a gamble choosing china things we know that.

1000W load is 4A and it was AC.. 4A load on a 25A SSR....

Yeap the worst part is that they short when they fail. Thats why its generally better with a proper contactor where you need to be able to disconnect.
completelycharged likes this post
The Ultimate DIY Solar and build place
YouTube / Forum system setup / My webpage  Diy Tech & Repairs

Current: 10kW Mpp Hybrid | 4kW PIP4048 | 2x PCM60x | 83kWh LiFePo4 | 10kWh 14s 18650 |  66*260W Poly
Upcoming: 14S 18650~30kWh | Automatic trip breakers, and alot more
Reply
#17
Just wondering what's the actual need behind "switching off the solar remotely"?
It is to stop charge, for safety isolation, ???
Might be other solutions?
Running off solar, DIY & electronics fan :-)
Reply
#18
30A DC, I believe... it's whatever these Voltronic type inverters are reporting. It's under 1600W power anyway so there's no way it could put out 30A continuous at our American 120v standard right? That would overload the inverter... so it's gotta be DC (I use a 48v battery but my grid is doing about 121v).

It's to stop charging if I'm at work and I need to for emergency. As things should work, the inverter will stop pulling so many watts once the battery approaches top SoC. If I get it balancing correctly then I won't need to turn off panels at all. BUT... I was having issues with my batrium system (and still am). And that's really what I need to fix. It doesn't seem to be balancing correctly at times, some cells get stuck in burn state and don't stop burning down when they should, causing other good cells to slowly go up and up way past correct top voltage.

I've been meaning to schedule some time with batrium to fix but life has gotten in the way and haven't had time.
Reply
#19
Surely inverter output isn't really relevant here?
You're talking about the input to the batteries from the solar panels right (not the output from batteries > inverter > loads)?
You'd mentioned 90VDC from the solar and 25A.

Switching this can be done with a few paralleled mosfets (or probably a single expensive high rated one).
I searched some of the vendors & there's 100's of Nch devices rated for Vds 150V to 200V.
Some looked like they could do it with just one device.
You would just control the gate with 12VDC (+ a 15V zener & a 10ohm drive resistor).
A heatsink, suitable weather proof enclosure, cable seals, termination blocks, etc, etc would be wise...

Other methods might be better/safer depending on the need/purpose.
If (when) it goes wrong, it has to be "safe".

Real question is still "what is the underlying reason for doing this"?
completelycharged likes this post
Running off solar, DIY & electronics fan :-)
Reply
#20
Underlying reason is:

Because Batrium is sometimes not protecting each cell (since something is wrong with it right now and I need to Tshoot) so this would be emergency plan B (or maybe C). Truth be told I still haven't done it and have mostly talked myself out of it at this point... what I really need to do is figure out why Batruim isn't working correctly (maybe wiring?) than worry about shitting of solar remotely.
Reply


Who read this thread?
98 User(s) read this thread:
hbpowerwall, daromer, Sean, mike, Majorphill, Korishan, A + A, PAF, jdeadman, wim, watts-on, jesusangel, Hanssing, Stefaan De Ridder, Chiptosser, BlueSwordM, Johnny Stauersbøl, Shade, Geek, floydR, hookemdevils22, DCkiwi, emerca, karmi27, bigblue, Ste Collister, Charly144, djuro, jm1, marcin, nrm21, gpn, mbrunton, jonyjoe505, Redpacket, completelycharged, Ibiza, Zvonko000, SilverNodashi, cadric, Cherry67, redalertdt, Sholphin02, Riplash, 100fuegos, bukvaahmed@gmail.com, w0067814, nkako, TheEngineared, chuckp, emuland-metroman, olde guido, lifepo4_powerwall, hazSolar, Beholder, Truth, runsnbunsn, Niemma, RayGenWurm, Wolf, Bastler_Ro, whoinow, iscience, Toubab, ibikunle, camthecam, Artlav, Generic, rettore, stevelectric, Guero, ajw22, MrMuzza008, RikH, Gstegman, raccooon, DomingoRP, Lagachette, wind0r, kevinjaye, SatgypsyD, LEDSchlucker, Tiger_one, zoookii, k.bz, sparkgap, spiderneo, ithai, Djpools, vivi0512, Church1182, i-craft, VOLTRON78, geoca, artex, strat24v, Alber, Dr mac

Forum Jump:


Users browsing this thread: 1 Guest(s)