Been reading and thinking but can't seem to find an answer

5 Posts
Apr 24, 2015 10:03 pm
Been reading and thinking but can't seem to find an answer

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« Last Edit: Apr 25, 2015 12:13 pm by Mark Osborne »
 
5 Posts
Apr 24, 2015 10:06 pm
Re: Been reading and thinking but can't seem to find an answer

x
« Last Edit: Apr 25, 2015 12:13 pm by Mark Osborne »
 
47 Posts
Apr 27, 2015 09:56 am
Re: Been reading and thinking but can't seem to find an answer

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And what is the question?

Amy
altE Store
 
5 Posts
Apr 27, 2015 11:06 am
Re: Been reading and thinking but can't seem to find an answer

Amy,  I discovered the answer through further research and couldn't find a way to completely delete my question.

Basically what I wanted to know is : Is there a (pure) grid tie inverter that can be configured to "not sell" to the grid ?  And to date, I don't believe they exist.

I have ran across several examples of people configuring inverters to "not sell", but in every case they were inverters that require battery banks. The new Radian jumps right out as an example with it's "grid zero" feature.

But in the case of a pure grid tie inverter, I can't find an example. People have suggested using timers and dumping extra current into hot water tanks and various other creative ways to prevent pushing electrons to the grid, but I've yet to find an inverter that can do it on it's own.

And considering how an inverter works IE: reads the line voltage and adjusts it's internal voltage to something higher- by design it's always going to attempt to "push" against the incoming voltage.

It would take some sort of monitoring device at the point of grid-tie, and then an internal voltage adjustment- accordingly -to accomplish what I'm suggesting. 

And, not to sound cynical, but why would any inverter manufacturer even offer such a critter ? !  they'd be cutting their own throats - meaning, you suddenly wouldn't need batteries, a charge controller and an hybrid inverter to accomplish "grid zero"... or so it seems to me.

I'll be most interested in your thoughts on the subject ....  ;-)

Mark
 
47 Posts
Apr 27, 2015 11:33 am
Re: Been reading and thinking but can't seem to find an answer

You are right, due to the basic design of a grid-tied inverter, they are specifically designed for net metering, spinning the meter backwards. Many folks who have turned on their inverter without a net metering agreement from the grid have ended up paying double, as they count the power generated by your inverter as power they provide and charge for it, since they don't know any differently. 

Since the inverter is designed to connect directly to the main breaker box, which is connected to the grid, you can't keep it from going out if your house is not using the power. And it is designed, per UL1741, to turn off if the grid isn't present, to prevent killing the linemen working on the lines during a power outage. So you can't disconnect it from the grid.

There's really not a huge demand to not send power to the grid, as that is the benefit of grid-tied systems, you use the grid as a battery to to send your extra power to, then buy it back when needed at night. I understand some grids are not "solar friendly", but they are currently the minority, and as such probably don't provide enough of a market for inverter manufacturers to completely change how the power is distributed.
 
5 Posts
Apr 27, 2015 12:53 pm
Re: Been reading and thinking but can't seem to find an answer

Yup, yup and yup.  I completely understand what you are saying and my research to date supports accordingly.

I've got a unique situation in that, I work from home and use the majority of the KWh's (20) during day light hours, and only 5 at night. I'd have no problem sticking up an 8000 watt PV array (or more), even aiming some west to gather what's needed later in the day if I could figure a way to be "grid zero" during the bulk of the day and pay the lousy 15 cents per KWh for the 5 I use at night.  Even IF I had do buy a couple Kwh's  here and there during the day .... no biggie.  In other words, produce the bulk of what we need - reducing the monthly bill by 75%.

Or local utility says we can only produce what we consume, on average, for the day and uses the past year's energy consumption as the basis for sizing the system, and even at that, I'll still be paying the customer fee of $6, nuclear decommissioning fees, and whatever else they decide to stick on here and there so I'll never completely devoid of an electric bill.

My line of thinking goes like this :  I'd rather stick up a few thousand watts more in PV (getting cheaper by the day) and say the hell with net metering.  I know, I'd miss all the fun of the electrical inspector, the local utility's yearly reviews, all the bureaucratic red tape that goes along with it, but somehow I think I could survive

But that's just my anarchist way of thinking... 

 
47 Posts
Apr 27, 2015 02:31 pm
Re: Been reading and thinking but can't seem to find an answer

If you can get around the Big Brother aspect of the Nest, I just saw this article today about the Nest potentially tying in with your solar system and making the time of use smarter.  It's giving Google a bit more information than I'm personally comfortable with.

http://www.forbes.com/sites/aarontilley/2015/04/20/how-googles-nest-will-make-residential-solar-smarter/

 
47 Posts
Apr 27, 2015 02:37 pm
Re: Been reading and thinking but can't seem to find an answer

It's hard to completely eliminate an electric bill. Remember you still need them for cloudy days, so they still have to be prepared and able to provide 100% of your power at any time, day or night. That's worth something there.  $6 a month plus whatever else is still a better deal than having to buy a big enough battery bank to go off-grid.
 
5 Posts
Apr 28, 2015 09:36 am
Re: Been reading and thinking but can't seem to find an answer

Very interesting... and feeds right into the topic of conversation Amy !
 

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