Why solar ‘tripping’ is a grid threat for renewables
eenews.net
eenews.net
apparently triggered by a fault on the grid linked to a natural gas plant in Odessa,
according to the Electric Reliability Council of Texas (ERCOT).
>“As in Texas, we’re seeing this huge boom in solar technology fairly quickly,” said Ryan Quint,
director of engineering and security integration at the North American Electric Reliability Corporation (NERC).
“And now, we’re seeing very large disturbances out of nowhere.”
">Out of no where.”
When a power grid falls out of tolerance (voltage and frequency),
all supply sources protect themselves by going off line to prevent equipment damage.Imagine a situation where every home is able to power itself with solar during the day (let's not include batteries to remove complexity from the scenario). The grid goes down, for whatever reason --maybe a tree fell and took out a main line, whatever. The entire neighborhood is now without power. Unnecessarily so.
Just talking about home solar installations, I think the inverters need to be design to keep running and isolate themselves from the grid if it goes down. The home remains powered and the thousands of solar arrays in the neighborhood can re-integrate into the grid when it comes back up.
My system uses SMA inverters. These have a feature that allows you to turn them back on in the case of the grid going down. However, they won't power the entire house. They have a separate output, 2000 W per inverter, that is energized when you enable this mode.
I have two special power outlets in the garage that are connected to the inverters. Should power go down during the day, I can enable that mode and then power whatever I want using extension cords, so long as I stay below 4000 W. A pain, but better than the ridiculous case of having sunlight and being without power.
Firstly on the solar supply side with no batteries, the supply to the inverter maybe considered chaotic,
we need to consider the fact that the stated '13kW array' is likely to be peak output power at say midday with no cloud/dust/shadow.
Therefore it is not feasable to consider a stand-alone system without batteries.
We need to know the total loads power factor (pf), assuming the inverter is rated at 13kW continuous at a pf of 1.0 (purely resistive),
and the rule of thumb average home load pf is .8 (slightly Inductive reactance) then your 13kW is; 13 x .8 = 10.4kW.
In large motors; pool/well-water/constant-water-pressure/hot-tub pumps some older washing machines a pf of .6 may be found.
Given the above, now we need to look at how chaotic the load currents are,
as a rule of thumb large motors have rated start currents of 5 to 7 times the run current for 5 seconds,
so 2.4kW motor (remember to de-rate the power-supply by the pf) will have a start current between 12kW and 16.8kW
12kW = 120v x 100A = 240v x 50A and 16.8kW = 120v x 140A = 240v x 70A.
So if you were building a house from scratch, we would wire it with supply and load in mind.
I designed and installed my own system. I regularly supply 8 to 9 kW to the grid (peak, of course). When the grid has gone down, I can turn on the system and supply the entire house without any issues at all, even without a battery.
I will probably install batteries sometime next year. The cost is still high. I need to wait until the ROI makes sense. My ultimate goal is to completely disconnect from the grid if possible. My guess is that I'll probably have to double my system size in order to be able to achieve this.
As I'm unaware of your location, I've added a search URL[1] which will IP geo-locate to your general area,
also you did not include the panel array power rating nor if batteries were included.
search: >'15kW Solar system'< @DDG : <https://html.duckduckgo.com/html/?q='15kW Solar system'>