Net Metering Questions.

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Greetings,

I have two questions about solar PV-based net metering. For the sake of argument, I'm ignoring the current municipal regulatory morass and concerned only with the technical possibilities. If I install solar panels and a generator with a grid tie inverter (with all anti-islanding safety equipment), will it feed power back into an active grid? If so, if I have a Eskom meter with the moving disks and rolling tumbler usage meter, will my PV power roll back the Eskom meter?

Thanks in advance.
 
The older spinning disk meters will run backwards.

I have one of these and was told by an electrician that it would run backwards.
 

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I attended a talk on this subject and the main guy said only medium voltage ie. above 1000v will be able to feed into the grid.So low voltage 220 and 440/380 v
is not able to feed back into grid.I stand to be corrected.
 
You are one of the lucky ones.

It will turn backwards - 100% sure. The beauty is you don't need to worry about your total usage patterns - say require a 5Kw system for " peaks " - just install a smaller one - say 1.5kw etc - IF your aim is to break even.

If you are however looking for a solution to keep the lights on during load shedding - you will will require a much larger system with a battery backup as well - a 3-5 kw system will be around 250K+
 
Fudzy said:
Won't your meter readers notice the figures are going down?
Click to expand...

It won't go down constantly. It will go up during usage at night (for the average person). And it will only turn the meter back if power generated by grid tie is greater than demand in the house during the day. On average, the meter will go up month-to-month but not as much as without the grid tie.

@OP : Not sure what you mean by generator "and" grid tie? For a grid-tie setup there is no generator. It's just the panels and the grid-tie inverter.
 
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Fudzy said:
Won't your meter readers notice the figures are going down?
Click to expand...


My meter is on the property and I email my reading every month. Of I were to go this route, I can just make sure that the reading is higher than the previous month.

Also the aim would be to be a net importer every month. Excess goes into the grid during the day with it being offset with night time usage.
 
I average about 800kwh per month with a peak demand of about 9.5kw. Been tracking my usage for the past two months with an efergy unit on the DB. Thinking of going with a 8/10kw grid tied system. No batteries for now as the inverter I'm looking at can take a generator as well for load shedding times.
 
Thanks all for the input. This site may help explain some background on this topic - http://www.exsolar.co.za/products/grid-tie-limiter/ .

It seems that with pre-paid meters all solar-based input to the grid does cause the meter to run forward, in essence charging you for the power you put into the grid as well as the power you take from the grid. No wonder the municipalities are pushing for pre-paid meters as replacement for the older types...

The meter I have is an older type, very similar to the one signates posted. So I have to think it will run backward with any solar-based power input to the grid as IguBu indicates. This in effect would remove the need for a battery back-up system as long as a generator were available for assisting the solar during blackouts. Eskom would be the battery as power fed into the grid would turn the meter backwards and this amount would then be 'free' when used later at night or when needed.

Plus, the exchange would be one-to-one on cost. No discounted price paid for power fed into the grid such as in some jurisdictions. The net would be 100%. Win win win. Guys, go check the junkyards and antique shops. Those older disk type meters are gold.
 
It is still illegal for me to go this route though. CT does have net metering though but require the installation of new four quadrant prepaid meter. The cost does not make it worthwhile though.
 
Apparently many or most old rotating disk meters will run backwards when you export power to the grid. I have been told that some are mechanically limited to prevent reversing, but don't know which or how you tell.

Can you not test yours by swapping the grid/load lines?

I've been exporting for over two years now. The municipality installed a four quadrant meter for that purpose.
 
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The whole disk running backwards thing is kinda sketchy. It's more accident than design and i doubt any of the techs are briefed on the possibility of the cables being live from the consumer side after grid side has been cut so it seems like a public danger to me until its properly managed.
 
Arthur - switching grid and load would amount to meter tampering. You're not entitled to mess with the cables on the grid side of the meter even for testing/trials
 
Arthur said:
Apparently many or most old rotating disk meters will run backwards when you export power to the grid. I have been told that some are mechanically limited to prevent reversing, but don't know which or how you tell.

Can you not test yours by swapping the grid/load lines?

I've been exporting for over two years now. The municipality installed a four quadrant meter for that purpose.
Click to expand...

Thanks Arthur, could you give us some data on your four quadrant meter set-up? Initial cost, direct payment or any crediting for grid export?
 
I have a InfinoSolar Inverter that is grid tied, I have an old meter and the disk does spin backwards, but the digits don't, They just stand still. The Infini does have s safety feature that if the grid fall away it will stop exporting, so there is no danger of somebody getting a shock when they work on the grid. Does anybody know who I can talk to in Pretoria to get my meter fixed so it runs backwards. I tried to phone Tshwane but I gave up after trying to explain the 10 time what I need.
 
I have a InfinoSolar Inverter that is grid tied, I have an old meter and the disk does spin backwards, but the digits don't, They just stand still. The Infini does have s safety feature that if the grid fall away it will stop exporting, so there is no danger of somebody getting a shock when they work on the grid. Does anybody know who I can talk to in Pretoria to get my meter fixed so it runs backwards. I tried to phone Tshwane but I gave up after trying to explain the 10 time what I need.
 
Just something else to be prepared for too (especially with a gennie)... If you DO net-meter, and Eskom shuts off the supply to do maintenance... You can expect to be hunted down with all hell and fury after you electrocuted an employee working on power that they assume is off (whilst you still energize it).

There's reasons why they must know WHO feeds back into the grid :D Contactor on your supply which disconnects when the supply is not energized, may be well advised for those wanting to do it in the "unofficial" ways.
 
savage said:
Just something else to be prepared for too (especially with a gennie)... If you DO net-meter, and Eskom shuts off the supply to do maintenance... You can expect to be hunted down with all hell and fury after you electrocuted an employee working on power that they assume is off (whilst you still energize it).

There's reasons why they must know WHO feeds back into the grid :D Contactor on your supply which disconnects when the supply is not energized, may be well advised for those wanting to do it in the "unofficial" ways.
Click to expand...
If a grid tie inverter does not switch off when you loose grid it should blow up because of the extra load
 
Hi Everyone, sorry for bumping this thread, but it is the only one that comes up in google searches...

Has anything changed in recent times ?

My Setup is a 5kw Solar array with a hybrid inverter capable of pushing back into the grid (I have set it to not do this), I also have a Hexing HXE12 Meter outside, and I am in Tshwane, will it run backwards if i feed excess power into it ?

I have tried talking to the municipality, and the meter company, and no one knows....

Maybe I should just feed some power into it, and see what happens...

I did find an article by the citizen saying Tshwane will allow it : https://citizen.co.za/news/south-af...k-electricity-with-new-solar-power-programme/

but ultimately not sure, can anyone point me in the legal direction ?
 
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