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Limiter inverter with RS485 load setting
#1
Bought one of these, which turned out to be a little bit different to what I was expecting.



The RS485 port recieves a data stream, which is the target wattage to output from the unit and that's it....

The monitor unit is a CT (upto 30A) and also sends out an RS485 stream with the current measured wattage (no sense of direction / import / export) so you then have to wire it up before the load metering (CT) location, which is a pain.

Where it can come in very useful is because of the RS485 you can then put the inverter wherever you want and then control the output directly.

What I have done so far is setup the monitor on a separate fuse box (which contains the house sockets circuits and kitchen) and then used a couple of RS485 to ethernet adapters to then allow me to put the inverter nearly 50ft away at the bottom of the garden where the battery pack is.

The next step is to make my own data feed up to control the inverter directly.

Protocol specification :
Data rate @ 4800bps, 8 data, 1 stop
Packet size : 8 Bytes
1 : 24
2 : 56
3 : 00
4 : 21
5 : xa (2 byte watts as short integer xaxb)
6 : xb
7 : 80 (hex / spacer)
8 : checksum


Still neeed to figure out the checksum (xor / sum / ?) and what the other bytes really mean or do, if they actually do anything other than hearder, trailer, checksum. The unit can be configured for upto 5 units so one of the bytes will be for this reason (load divider).

Anyhow, hopefully this is of use.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#2
Brief update. Unit has been running for a few weeks and seems to be ok, although the meter reading with some appliances fluctuates quite a bit so guessing the reading is an instantanious value (not average) at some point in the sine wave so any noise/choppy waveform will create fluctuations in the output that are not necessarily needed.... unless you have a separate meter feed to control the output rather than the basic meter that comes with the unit. Real shame they do not have directional metering.

There seems to be 2 versions, listed as 1000W and 1200W, however the only difference seems to be when running on battery the 1000W unit can "sustain" 800W and the 1200W can sustain 900W (go figure as to how the ratings are derived...). I have a couple of the 1200W units due to arrive and will see how they work on a separate circuit and compared to the 1000W unit. Suspecting they are identical and just typical Chinese rating confusion / nonsense, hopefully not.

Internally there does appear to be space for additional components in the 1000W unit, so the 1200W units may have these added and will find out when I get the 1200W units to have a look at and compare.
Korishan and hbpowerwall like this post
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#3
Have a URL for it?
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#4
I wish I could use these legally in Australia - they are hit and miss on their reviews but i guess if I got a 2000w unit and only run it at max 1000 ish watts it should last ok.
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#5
These are the units (check for pricing from different sellers as they are all a bit random)
https://www.aliexpress.com/item/1200W-Gr...94320.html

They are only 1000W or 1200W rated units, so not the GTIL units that have been the choice for many and which is what I was originally planning to use. Will clarify what the difference really is soon.

The main benefit I saw with these was the simple RS485(232) control option, give it a number and it changes the output. Runs around 4Hz on output update rate.

Found out last night the output appears to start to de-rate below 47V input voltage.

In terms of grid compliance for connection they are problematic (no harmonics certification test for use) however the critical delay start timing can be changed to be compliant and this is the what I see as the main danger presented by any grid connected inverter connecting too quickly to a restored grid supply. Harmonics, add a separate external filter. Whole sepatate discussion..

My longer term intention is to use them off-grid in conjunction with a separate off-grid inverter for incremental sustained inverter capacity.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#6
I bought/used the 1000W version of this in 2018 - for about 4 months with no problem. I love the settings (battery voltage on/off, power limits) as I was too far away from main panel to use the clamp/limiter. I stopped using it in 2019 because its not ETL/UL listed - whereas all my other components (including the Inverter) are.

How do you feel about ETL/UL? - do you worry about it as a risk at all?
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#7
This is my view and not necessarily what should be followed as I have a slightly different arrangement...

Like with all laws/legal isses they are usually implemented to preven abuse of a system OR sometimes introduced as a means of creating competitive advantages in the guise of 'higher standards' (blocking imports for example).

Testing standrds seem to cover 3 elements (I'm separating outright electrical build quality here, which is a little easier to see) :
1. Anti-islanding (will your 800W inverter try to power the neighbourhood for longer than it takes for the FET's to blow magic smoke or will it reconnect and export far too quickly if linesmen are fault finding for example)
2. Harmoniocs (mainly to prevent square wave or partial wave inverters from introducing resonant issues and destroying other appliances.... typical HF units with reasonable filtering are zero issue, unless they are HF broadcasting with a really bad desing)
3. Stability (will your interter cut out if the grid becomes unstable, like if it was connected to a generator running out of fuel - this is typicallly an issue for large power stations as a phased/steepped frequency stability measure, not an issue for the home/kW size)

Voltage levels are a given basic for any equipment, so if they don't show or indicate the on/off limits then I would avoid them for example. Basic lack of control.

If your equipment is designed and operates within the required standards, just because it does not have a testing label/stamp of approval it does not mean it is therefore dangerous to the system just because it does not have a $ XX,000 stamp of :

https://www.youtube.com/watch?v=A9sd10CHAP8

This is also where the laws are intoduced because the few who produce real cr*p that destroys it for the many.

Summary : end of the day it's your own risk (and risk to others), just like when speeding in a car as every motorist does and it is therefore the balance of what risk is acceptable (Boeing 737).
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#8
So, after installing and a few more days of operation I now have 3 of these units active and balancing out 2 distribution boards.

The lighting board (also the shed) has one 1000W unit matching the power flow and then a couple of 1200W units, which are then matching the power from the sockets/kitchen.

The metering point in the house has two of the current clamps around the 16mm cables feeding each board (the current clamps need the plastic trimming so they will fit over the cable) and then the output from each meter is fed into an RS485 to thernet adapter, whcih is then plugged into the network. The third current clamp (each unit came with a CT and RS485 output box) is then connected on the main feeder so I can have a rough indication as to the magnitude of the residual imbalance (good way to get an idea on the CT accuracy 1+1=2.2).

The battery location in the shed then has two ethernet to RS485 adapters with the output from one going into a 1000W unit and the other going in paralle to the two 1200W units.

The "1000W" unit will only give out 800W when running off battery and recieving RS485 output level.

The two "1200W" units will only give out 900W each when running off battery and recieving RS485 output level, so 1800W in total.

I think (guess) that they derate the units when operating on battery because when they are running off solar the input power is limited by default so any fault issues will not cause significant stresses, while a battery with 100's of amps capability will quite hapily blow the PCB traces off the board. Sort of an easy addition of hopeful safety margin to faults... that's my guess.

Overall, seem to work ok, the current clamp accuracy may be a bit suspect (less accurate than I would like).

Will add some pics.

Separate note, the internal fans come on at 40C and then only relatively briefly (with 25C ambient), although I have a separate small fan (few W) blowing on the units 24x7 just to give a little more than convection flow for normal cooling. Thought is that by reducing the temperature by say just 5C the operational life of the capacitors will be extended quite a bit.... When really hot days arrive I also turn off some of the solar input to reduce the temperature on the MPPT controllers... fortunrately or unfortunately for us in the UK we don't get many 30C plus days.
If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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#9
(07-05-2019, 09:31 PM)completelycharged Wrote: Protocol specification :
Data rate @ 4800bps, 8 data, 1 stop
Packet size : 8 Bytes
1 : 24
2 : 56
3 : 00
4 : 21
5 : xa (2 byte watts as short integer xaxb)
6 : xb
7 : 80 (hex / spacer)
8 : checksum

if you understand what those bytes mean, it would be very nice (and maybe i can help) to write a python software to give data to this grid tie.

and maybe throw away that clamp and use a rs485 panel meter like eastron one.
Building Lifepo4 Powerwall - atm 1400 cells growing

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#10
Will try and get the full protocol out from the manufacturer (some hope...) because the units appear to be programmable for constant voltage, constant current and constant power (default)...

Suspect the 24/56 is a standard hearder for the device.
00 - single unit active (increases by 1 per unit - acts as a divisor for the power measurement)
21 - no idea

Or could be just simple 2 byte word packet.
Unit ID
Unknown/settings (21 = Constant power mode as a guess ??)
Target setting in Watts/Volts/mA
Checksum

They are interesting units and possibly one of the most accessible (output setting options) cheap inverter uinits on the market at the moment, shame they lack official grid certification in virtually every country in the world....

If you can't quantify how much they cost, it's a deal, I'll buy 5 of them for 3 lumps of rocking horse ......
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