Using Extended Variables to Monitor Multiple Phase Power


#21

This in an interesting read on the subject. However, it doesn’t really seem offer the solution to which the PV system owner can contribute except the suggested changes in inverter settings and shifting his off peak power draws such as water heaters, washers, dishwashers, etc to mid day.


#22

My hot water is on a controlled load, so the grid determines when that is turned on. Currently that happens after 11pm typically and occasionally during the day on weekends I suspect (no real monitoring visibility on that).

The grid here has a lot of demand capacity on controlled load, so the grid itself already has quite a demand control tool at its disposal.


#23

I should have responded much sooner… As of this very moment:

        "Voltage_AC_PhaseToPhase_12" : 421.80000000000001,
        "Voltage_AC_PhaseToPhase_23" : 422.69999999999999,
        "Voltage_AC_PhaseToPhase_31" : 424.39999999999998,
        "Voltage_AC_Phase_1" : 244.5,
        "Voltage_AC_Phase_2" : 242.5,
        "Voltage_AC_Phase_3" : 245.59999999999999

#24

When I try:
solar_api/v1/GetMeterRealtimeData.cgi

All I get is:

{

“Body” : {
“Data” : {}
},
“Head” : {
“RequestArguments” : {
“DeviceClass” : “Meter”,
“Scope” : “”
},
“Status” : {
“Code” : 6,
“Reason” : “CGI-Args: Invalid parameter ‘’ for attribute ‘Scope’ (use ‘System’ or ‘Device’)”,
“UserMessage” : “”
},
“Timestamp” : “2020-06-10T18:50:03+10:00”
}
}

It’s not clear to me from the Fronius API document how to correctly format the request. It shows a bazillion examples of outputs but never an example of how to format the input request.

Any clues. Fumbling in the dark here. :slight_smile:


#25

Interesting that the grid wants you to use their low rate and not your solar power at zero rate. Can you take it off controlled load and control it yourself?


#26

You were close… Try http://fronius/solar_api/v1/GetMeterRealtimeData.cgi?Scope=System

Where ‘fronius’ is the IP of your inverter unless you are using local name resolution.

The documentation is a bit confusing. I had a lot of trial and error to work out the correct syntax for some of the API calls.


#27

As of right now the export tariff and controlled load import tariff are so close it makes no sense to go to all that bother and cost. And this winter I’ll be changing plans most likely and will be on one where we get paid more for our exported solar PV than it costs to import on the controlled load.

IOW using my own solar PV for hot water would cost me money.


#28

Thanks!

This is the AC voltage response I get right now (5.54pm):

"Voltage_AC_PhaseToPhase_12" : 421.60000000000002,
"Voltage_AC_PhaseToPhase_23" : 421.89999999999998,
"Voltage_AC_PhaseToPhase_31" : 422.60000000000002,
"Voltage_AC_Phase_1" : 243.80000000000001,
"Voltage_AC_Phase_2" : 243,
"Voltage_AC_Phase_3" : 244.19999999999999


#29

I just realised I had assigned a static IP address and name for my inverter, and can simply use “FroniusSymo”.

Yeah, not being a network person I need examples.


#30

I would be too lazy to use something like FroniusSymo so I simply stuck with fronius. My Rasperry Pi is pi and so on. I’d have to be more imaginative if I ever had a reason to get a second one for some reason. :smile:


#31

It is much different here in California. They don’t pay much for your excess energy and it makes sense to use as much (1 to 2 cents /kWh) of your over production as possible. As a result we do all our major appliances at mid-day. We don’t consume very much but we have a large house, no AC and Winter heating is minimal. Hot water and heating is with gas but the two furnaces consume electric for the fans. Our whole house consumption is between 12 and 20 kWh Summer to Winter. We have converted most of our lighting to led’s which resulted in a 25% reduction in consumption. Before Solar we were averaging 23 kWh’s per day over the year. Our rates are high being around $0.50 per kWh. Right now we are on an old rate schedule which will end next year and will be moved to a TOU rate schedule. Our over production is paying all the costs up to now so we have not had to pay a penny to the electric and for three years got back around $300 at the ridiculous rate. Still the electric company is trying to get us to pay for the privilege of giving them free electricity.


#32

2 x furnaces - I always thought of California as a fairly warm climate my views shaped in the main by watching too much television. I guess though that the moment you move inland, North or up in elevation things would cool down quite a bit.


#33

At 33° N latitude at sea level we do get some cold in the winter months. However, it doesn’t often even frost here at that time of year. The winter months is when we get almost all our rain. Overnight temperatures can dip well into the 30’s and 20’s F so we often need the furnace on at least during part of the night and sometimes the day.
The reason we need two furnaces is that a large ranch style house is better heated by two sources. Even though the installation is more costly it is actually more economical since you only have to heat half the house at a time now that we are in our retirement years. Last winter was mild and we hardly used our furnace. Other years we have needed them very frequently. Like other weather it is cyclical. Average Winter temperatures vary from 45° to 90°, the latter occurring infrequently. For the most part it is a very comfortable place to live year round.


#34

That’s southern California, down San Diego way I guess.

We are ~30.5° S, east coast Australia although inland from the coast by about 15km.


#35

An example of how power consumption affects voltage on one of our phases:

Here’s power and voltage on line two, with the numbers showing for 5:15am:

and the numbers at 5:40am after I had turned on the reverse cycle ducted aircon system to get some heating happening:

That’s a drop of 14.2V from 244.0V to 229.8V for a power demand of ~4kW.

Seeing a ~3V variance per kW of load change is about normal for us. I see the same each night when the controlled load hot water (3.6kW resistive element) turns on and off, usually results in a ~10V variance on line 1.

The solar PV system of course both lightens grid power draw and exports excess production, both of which work to increase line voltages during the day, often to above grid standards. Our inverter is often managing production to keep voltages from going too high.


#36

That’s a fairly serious voltage drop. It must be time for the electricity distribution company to invest in some thicker conductors?


#37

I don’t think that’s the problem. More the line length (~380m) and transformer capacity.

When I got approval for the granny flat they gave me two choices. Add a 32A/phase circuit breaker to the mains supply, or pay them to upgrade the network, which the electrical consultant told me was going to be in the order of $35-50k.

I’d say that transformer has ~60kW of PV panels feeding it.


#38

on a single wire power supply my voltage has swung today with a 10 amp load, between 235 v and 252 volts-- 17 volts swing,and the sky wire and transformer have both been replaced in the last 12 months,sky wire length about 700 mts,