Backfeeding the grid

Do the reviewed MPP Solar Power Inverter/MPPT/Charger systems push surplus power to the grid when batteries are full,
or is the grid connection only for charging batteries and supplying the load when the batteries are not capable of doing so?

I have LV2424 and it can back feed grid when battery is full
It’s a grid tie settings in the menu

ytwytw said:

I have LV2424 and it can back feed grid when battery is full
It’s a grid tie settings in the menu

Click to expand...

To be clear are you saying you can turn off the back feed into the grid?
One of the drawbacks of these is in a power outage they are a dangerous device for backfeeding and killing a linemen.

Having the ability to sense grid power and subsequent shutoff would be a mandatory requirement for these things.
If they don't they would be illegal in most areas.
Your liability would be huge

Can someone clearly answer this.
Is there a setting so they shut off in a power outage?

You can choose off-grid mode or Hybrid Mode (Backfeeding)
The problem is the backfeeding only happens when battery is fully charged.
In my case, I have 1.6kW solar but 9.6kWh Golf Battery system, it will never get fully charged unless i choose so.
According to the manual, backfeeding is a real grid tie system, once the grid is off, the backfeeding stops.

ytwytw said:

View attachment 1540

You can choose off-grid mode or Hybrid Mode (Backfeeding)
The problem is the backfeeding only happens when battery is fully charged.
In my case, I have 1.6kW solar but 9.6kWh Golf Battery system, it will never get fully charged unless i choose so.
According to the manual, backfeeding is a real grid tie system, once the grid is off, the backfeeding stops.

Click to expand...

I'm not finding in the manual where it states that backfeeding stops when the grid is off. Can you direct me to that section?

mtt04 said:

To be clear are you saying you can turn off the back feed into the grid?
One of the drawbacks of these is in a power outage they are a dangerous device for backfeeding and killing a linemen.

Having the ability to sense grid power and subsequent shutoff would be a mandatory requirement for these things.
If they don't they would be illegal in most areas.
Your liability would be huge

Can someone clearly answer this.
Is there a setting so they shut off in a power outage?

Click to expand...

This device has Anti Islanding as a industry standard , so in the case of a power failure - it would not feed back.

Thanks Ian
Safety first

Ian Roux said:

This device has Anti Islanding as a industry standard , so in the case of a power failure - it would not feed back.

Click to expand...

Exactly how would this be accomplished? If the unit stops producing power with the power off, then it would be anti islanding... if it provides power during an outage, and is tied into the grid... I dont see how it can anti-island...

The MPP all-in-one PIP models do not back feed the grid. ️

MrNatural22 said:

The MPP all-in-one PIP models do not back feed the grid.

Click to expand...

We are actually talking about the non-pip ones.

When we install these other ones there is concern around whether the generation station continues to pump power into the grid.

For instance I need a split phase solution for 220v to power my garage mini split which is 220v.

There must be a way for my solution to not send power back into the grid during an outage.

This was the purpose of the question.

Thus the trail of responses. All transfer switch solutions I've seen sense power loss and shut down grid feed. But it important to know for sure that this happens.

I'm not interested in grid tie to spin my reader backwards. My purpose is to use grid when my battery bank is low.

Cheers

mtt04 said:

We are actually talking about the non-pip ones.

When we install these other ones there is concern around whether the generation station continues to pump power into the grid.

For instance I need a split phase solution for 220v to power my garage mini split which is 220v.

There must be a way for my solution to not send power back into the grid during an outage.

This was the purpose of the question.

Thus the trail of responses. All transfer switch solutions I've seen sense power loss and shut down grid feed. But it important to know for sure that this happens.

I'm not interested in grid tie to spin my reader backwards. My purpose is to use grid when my battery bank is low.

Cheers

Click to expand...

If the grid is on the input of the inverter, and the output is to your garage, the inverter shouldnt feed the grid ever, grid up or down.

Lets start from the beginning...

When you take the unit out the box, by default, the grid feedback is DISABLED (It operates exactly like a PIP unit).

You can connect Grid/Utility power into it (If you wish/ Optional) or it can operate completely off-grid.

If its in your camper, etc , Just connect the 24V battery, and if its charged, turn the switch on, and it happily runs along.

Connect Solar , and it will charge the battery whether the inverter Switch is set to on or off, the batteries will still charge (inverter on or off)

If the Battery runs low, make sure your Low Voltage Cutoff is set higher than default, you dont want your batteries to become completely exhausted (and shut off before the inverter does)


Now if you connect Utility Power, you can choose from the standard options what you would like to happen when:
A) The Inverter is overloaded - it will automatically switch the load over to grid/utility power
B) Pass though Utility power to the load, and keep the battery charged - if the Grid fails, the output will switch to the inverter, and power will be used from your batteries.
C) or.. If running on Solar and Battery, and the load is more than the battery and solar , it can supplement power from Grid/Utility (It does this via it internal Utility battery charger)
D) or of the battery is running low, switch the load over to utility/grid and charge the battery at the same time (if solar is present, this will also charge the battery at the same time).


So far all pretty standard.

No if you wish to enable the grid/utility feedback option (setting number 09 in the manual and will operate within the parameters set in settings 03 and 04), this function only operates when A) Battery is fully charged AND Solar Input is still generating power).
The excess Solar energy (Solar minus Load) will ONLY be fed into the grid if there is an incoming voltage from the Grid, in other words, if the grid/utility fails (or drops below the regulation voltage on page 28 below) , then ZERO power will be fed back into grid. So , if the grid voltage rises above regulation grid voltage or below regulation grid voltage it will stop feedback immediately. It will not feed back power when the grid it down.

On page 28 of the manual it shows the various countries regulation for grid feedback (South America and North America

The grid feedback system works it will slow your meter down even if you don't have net metering.

UL listing is on schedule for early 2020 for this particular model (It has approvals for European countries in its current 120V and 240V option).
We ask customers to NOT use this function in a formal setting, but we do have many customers who use it, and have the approval and buy in from their local utility companies too.


IF the grid had to go down while you were using this grid feedback option, all that would happen is the following:
A) Grid feedback would cease
B) Your Inverter will continue on as normal with inverter/battery and solar power (you would not even notice the power failure)
C) The inverter would only shut off if the battery were to run low.
D) If the grid power was restored, the inverter will continue to provide power according to your setting priority, until the battery is fully charged, at which point it would begin feeding to slow your single meter down / or add to your net metering meter.

Here is the Wiki definition of Anti Islanding. (this inverter supports anti islanding - it will not become a (Grid) power island unto itself)

Islanding
From Wikipedia, the free encyclopedia


Jump to navigationJump to search
Islanding is the condition in which a distributed generator (DG) continues to power a location even though electrical grid power is no longer present. Islanding can be dangerous to utility workers, who may not realize that a circuit is still powered, and it may prevent automatic re-connection of devices. Additionally, without strict frequency control the balance between load and generation in the islanded circuit is going to be violated, leading to abnormal frequencies and voltages. For those reasons, distributed generators must detect islanding and immediately disconnect from the circuit; this is referred to as anti-islanding.
A common example of islanding is a distribution feeder that has solar panels attached to it. In the case of a power outage, the solar panels will continue to deliver power as long as irradiance is sufficient. In this case, the circuit detached by the outage becomes an "island". For this reason, solar inverters that are designed to supply power to the grid are generally required to have some sort of automatic anti-islanding circuitry.

Finally!

A clear concise explanation.
Thanks Ian

As I am grid tied in my garage I will wait for UL listing as per local code. We can't install non UL or CSA approved gear here.

I will use mppsolar for my garage solution as I need grid support for my battery bank to run my heat pumps.

I simply wanted it done safely.

Your support to us here has been very helpful.

Thanks

MPP Solar USA - Ian Roux said:

The grid feedback system works it will slow your meter down even if you don't have net metering.

Click to expand...

I have one of the digital meters that FPL can read remotely in real time. I've always wondered, if I backfeed the system shouldn't I expect a knock on the door, or a lineman disconnecting me? Especially if I'm producing more than consuming and am not set up for net-metering?

mtt04 said:

One of the drawbacks of these is in a power outage they are a dangerous device for back feeding and killing a linemen.

Click to expand...

'
Unless you live way out where no other houses are, it's very unlikely. If you live in a neighborhood and your grid goes down..and you are dumb enough to be backfeeding improperly without an anti-islanding inverter or shutting off the main...you know what happens? Your generator/inverter trips it's own breaker or fuse. Why? Because you are backfeeding not just the lines on the pole, but all your neighbor's houses too! The load would be too great...and instantly pop any protection circuit...or harm something.

This is one big reason even the cheapest of these backfeed inverters will provide anti-islanding. Not necessarily to protect linemen, it's to protect the device itself.

SolarRat said:

Because you are backfeeding not just the lines on the pole, but all your neighbor's houses too! The load would be too great...and instantly pop any protection circuit...or harm something.

Click to expand...

Many, many moons ago, before I had an interlock on the breaker panel, I accidentally left the main on while backfeeding. While the generator and the panel breaker did not pop, the genny was dragged down so low it was practically useless. I realized what I had done in a second and manually tripped the breaker, but had I let it go, I'm sure the breaker would have eventually tripped. Not a good way to find out how things work.

SolarRat said:

I have one of the digital meters that FPL can read remotely in real time. I've always wondered, if I backfeed the system shouldn't I expect a knock on the door, or a lineman disconnecting me? Especially if I'm producing more than consuming and am not set up for net-metering?

Click to expand...

quick answer is "No" they will have no way of telling, your pole meter cannot (the ones I know about anyway) turn backwards, so all it will do is not run at all during the day if you make more than you use.

Best
Ian

Some of the old mechanical spinning disc style meters actually have a tell tale flag that pops up if the meter is ever run backwards. It was to combat people that plugged in adjustable devices that cause the meter to run slowly or even backwards if the device was not adjusted properly which was hard to do given the normal variation in draw.

If you back feed and do not have a net meter, you will be paying for what you are supplying to the grid!
The meter only knows the current is flowing, it doesn't know you are sending it or receiving it.

So don't back feed. The best you can hope for is slowing down your grid meter to at or near zero.

Most newer inverter/chargers hooked up to the grid have a "battery preferred" mode which means it'll run off your battery until it dips below a voltage you set then it's internal transfer switch will switch back to grid power to service its loads and start charging the battery (or not if thats how you want it). It'll also switch back to the grid if you overload the inverter.

Since you dont have to deal with net metering and permits thats not a bad way to go, you're making and consuming most/all of your own power and reducing your electric bill, unless you've got a 8kw or bigger solar array you only make peanuts feeding the grid anyway, certianly not enough to pay for the hardware and installation.