Micro Inverter and Smart Meeter

[lasix]

I am looking to put up a small solar system on the roof of our home. I am thinking about 1 kw. I want to used one of the plug n play grid tie inverters. I also have a smart meter, and I do not want to have any of the problems that are associated with a smart meter and these grid tie inverters when the system produces positive electric. So I had a question

1. Is there a way to use a blocking diode before the utility meter, so no positive gains would be seen?
2. what would happen to the "extra" electric? Would it be a problem?
3. If there is no problem, or a way to overcome the problem in number 2, what type of blocking diode would I need?

Conversely, I was thinking of using maybe 3 80AH batteries and have the house run off the battery system inverter, then auto-switch to the grid when the battery bank has depleted to a certain threshold. How would this be accomplished?

thank you very much.

[Sunking]

A1. No
A2. Smart meters will count that energy as energy used by you, and you will be billed for it. It will also alert the POCO you have an illegal connection.
A3. I think I covered that already.

[russ]

I want to used one of the plug n play grid tie inverters.

Not to mention an outlaw connection would likely invalidate your homeowners insurance in the event of a problem.

[Naptown]

Try this
Tell the utility you are installing solar and have them update the meter software to a net metering arrangement.

[billvon]

Conversely, I was thinking of using maybe 3 80AH batteries and have the house run off the battery system inverter, then auto-switch to the grid when the battery bank has depleted to a certain threshold. How would this be accomplished?

With LBX (low battery transfer) on a standard (non grid tie) inverter. 3 80AH batteries would probably run some loads in your house for 15 minutes before hitting the LBX limit and switching back to grid. (Alternatively it would just trip the LVD and shut down.)

Batteries last about 500 cycles if you take care of them, far less if you don't. Thus if you ran through that cycle 10 times a day you'd need new batteries about once a month.

[lasix]

A1. No
A2. Smart meters will count that energy as energy used by you, and you will be billed for it. It will also alert the POCO you have an illegal connection.
A3. I think I covered that already.

Hence the reason for the blocking diode...................

[lasix]

Not to mention an outlaw connection would likely invalidate your homeowners insurance in the event of a problem.

Thank you for your input, but it did not address the question.

[lasix]

Try this
Tell the utility you are installing solar and have them update the meter software to a net metering arrangement.

Not a UL# associated with the gird tie inverter...

[billvon]

Hence the reason for the blocking diode...................

Diodes don't block AC.

You're not going to be able to get around getting an approved installation. If you really want to test out some non-UL inverters, then get a small (1kW? 500W?) conventional solar power system installed and permitted. That takes care of the utility getting fussed about an illegal grid tie system and you get some reliable solar. Then you can experiment with those non-UL inverters without worrying. (And by watching the install and seeing how it works you'll learn a lot about safe and effective solar installations, to boot.)

If you REALLY don't want to have anything to do with the utility then set up an independent system charging a battery, and operate a few loads from there. If you do this I strongly recommend doing it in a container or shed outside so that any fire/smoke from problems (too-small wire gauges, cheapo inverter going up in flames) doesn't affect your house.

[lasix]

With LBX (low battery transfer) on a standard (non grid tie) inverter. 3 80AH batteries would probably run some loads in your house for 15 minutes before hitting the LBX limit and switching back to grid. (Alternatively it would just trip the LVD and shut down.)

Batteries last about 500 cycles if you take care of them, far less if you don't. Thus if you ran through that cycle 10 times a day you'd need new batteries about once a month.

Basically the day time we have very good sun coverage, and 1kw will cover most of the idle current use clocks, computers plugged in, TV/DVR stand-by, occasional fridge etc... The need for the batteries would be to prevent the constant surges from periods of low sun passing clouds for example.

What I was thinking of doing is having a "back-up auto switch" set in reverse (If this is possible) and with no down time. For example the battery bank and PV would supply the needed electric draw to the house. When the V on the battery is say V=11.4, auto-switch to the grid.

Regardless of the battery expense, is this possible? Any ideas on what inverters or controllers will allow this type of set up?

Thank you for your response.

[billvon]

Basically the day time we have very good sun coverage, and 1kw will cover most of the idle current use clocks, computers plugged in, TV/DVR stand-by, occasional fridge etc...

What's an "occasional fridge?" One you use only for parties, then unplug?

A regular refrigerator (20 cu ft, auto defrost) is going to take on the order of 5kwhr a day. A DVR takes around 1.2kwhr a day. (It's effectively always on even if it tells you it's off.) So overall you are talking a fair amount of load.

What I was thinking of doing is having a "back-up auto switch" set in reverse (If this is possible) and with no down time. For example the battery bank and PV would supply the needed electric draw to the house. When the V on the battery is say V=11.4, auto-switch to the grid. Regardless of the battery expense, is this possible? Any ideas on what inverters or controllers will allow this type of set up?

Yes, the old Trace SW series supported this and they are still occasionally available on Ebay and the like. Here's the relevant section from the manual:

================================================== =================
LBX - The low battery transfer mode allows a system to automatically switch between utility
connected and stand alone battery operation. In this mode, the inverter will power the loads from
the battery and solar array (or other energy source) until the battery voltage drops to the LOW
BATTERY TRANSFER VDC setting. It will then connect to the utility grid and charge the battery. The
loads will be powered by the utility until the battery voltage reaches the LOW BATTERY CUT IN VDC
setting. The inverter will then disconnect the utility and power the loads from the battery and any other
source of DC power connected. This mode is often used instead of the SELL mode because approval
from the utility is not required - no power will be sent into the utility distribution system when LBX is
selected. To use the LBX mode, the AC source (utility power) must be connected to AC1 input only,
transfer to the inverter will not occur if the AC source is connected to the AC2 input. If AC is present
on the AC1 input in the LBX mode, the AUTO GENERATOR CONTROL MODE will be disabled.
Caution: If the system is not properly sized, the LBX mode can result in frequent transfers from the
battery to the utility and result in poor performance of the system and excessive energy consumption
from the utility. The daily output of the alternative power source (solar, wind etc.) should be able to
meet the daily power requirements of the loads being operated under typical conditions. See the low
battery transfer mode section for more information.
================================================== ====

[lasix]

Diodes don't block AC.

You're not going to be able to get around getting an approved installation. If you really want to test out some non-UL inverters, then get a small (1kW? 500W?) conventional solar power system installed and permitted. That takes care of the utility getting fussed about an illegal grid tie system and you get some reliable solar. Then you can experiment with those non-UL inverters without worrying. (And by watching the install and seeing how it works you'll learn a lot about safe and effective solar installations, to boot.)

If you REALLY don't want to have anything to do with the utility then set up an independent system charging a battery, and operate a few loads from there. If you do this I strongly recommend doing it in a container or shed outside so that any fire/smoke from problems (too-small wire gauges, cheapo inverter going up in flames) doesn't affect your house.

Thank you for the information for the diodes re AC, however they always work in blocking the negative current. only it will "look" like DC afterwards, and would need to be rectified and converted back to a sine wave. Maybe I am asking the wrong person...

My question is what devices are suitable for handling the voltage and amps that a house can load up to? AND since there is a block preventing the return of my made energy to the grid, what happens to the excess energy?

PS they want 25k to install the smallest system on the home 250W....

[billvon]

My question is what devices are suitable for handling the voltage and amps that a house can load up to?

Assuming a battery bank? The XW6048 is a good "whole house" inverter, and will run most loads in a typical house (i.e. no electric heat or large pool systems)

AND since there is a block preventing the return of my made energy to the grid, what happens to the excess energy?

It is not harvested. It effectively "stays in the panels."

PS they want 25k to install the smallest system on the home 250W....

Someone is trying to rip you off.

[Mike90250]

Thank you for the information for the diodes re AC, however they always work in blocking the negative current. only it will "look" like DC afterwards, and would need to be rectified and converted back to a sine wave. Maybe I am asking the wrong person...

My question is what devices are suitable for handling the voltage and amps that a house can load up to? AND since there is a block preventing the return of my made energy to the grid, what happens to the excess energy? ....

Correct, you asked honest people. There is no simple way to monitor and divert AC power with a diode.

If you turn the diode over, it will block the positive current ! Use 4 of them and you have a Bridge Rectifier.

It would require a very fancy hunk of machinery (and very expensive) to do as you are asking. Power just
does not flow that way.

[inetdog]

Thank you for the information for the diodes re AC, however they always work in blocking the negative current. only it will "look" like DC afterwards, and would need to be rectified and converted back to a sine wave. Maybe I am asking the wrong person...

You have hit the nail right on the head with your mention of rectifying and then converting back to AC. That is what some UPS systems do, and that provides full isolation against backfeeding power. But what you may not realize is that you would have to do that with all of the incoming power from the grid and use it to drive your house loads through a great hulking inverter. That is far from a simple diode. And unfortunately a simple grid-tie inverter rather than a hybrid inverter on your solar panel output will not work when it sees that inverter. So sad.