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"New" version of grid tie on its way


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Interesting the concept now starting to take shape in SA means that soon I will be allowed to sell to my neighbor and don't have to sell to COCT or buy from my neighbor.

Thus I can sell my excess @ let say R 1.20 and do not have to sell to a munic or Esdom.

Also means I will be able to buy from any generation connected to the grid.

Pretty much how USA & UK ... works.  Ever wonder why Esdom created a third leg called distribution or networking.  For this very reason.

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I always had a hope that a private power exchange similar to PowerX would come onto the scene, someone willing to close power purchase agreements with smaller household installations, aggregate that power on a national scale, and sell it off to customers. For any one household it's probably small, but how much power is lost through solar panels sitting idle on rooftops all over the country at any given time?

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1 hour ago, GreenFields said:

I always had a hope that a private power exchange similar to PowerX would come onto the scene, someone willing to close power purchase agreements with smaller household installations, aggregate that power on a national scale, and sell it off to customers. For any one household it's probably small, but how much power is lost through solar panels sitting idle on rooftops all over the country at any given time?

Looking at some of the pv graphs on this thread I would estimate that between ¼ to ⅓ of residential pv is lost due to panels sitting idle after batteries are fully charged and loads are taken care of. How much MW that is I have no idea as there's very little data on what's currently installed in the residential market. 

My own 10kwp will sit idle from around 12:00 when batteries are full and only needing to supply 1kw to 2kw for the loads. 

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Part of Elon Musk's vision is the ability to use your car's battery to sell power to the grid when the prices are high and charge it when the prices are low.

Prices would be variable based on supply vs demand, so on days with no sun/wind the price goes up etc

Can you imagine the grid if everyone has 100kw/hr of power sitting in their garage that can feed back into the grid during high demand times. 

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On 2021/08/03 at 8:41 PM, Erastus said:

Interesting the concept now starting to take shape in SA means that soon I will be allowed to sell to my neighbor and don't have to sell to COCT or buy from my neighbor.

Thus I can sell my excess @ let say R 1.20 and do not have to sell to a munic or Esdom.

Also means I will be able to buy from any generation connected to the grid.

Pretty much how USA & UK ... works.  Ever wonder why Esdom created a third leg called distribution or networking.  For this very reason.

In the UK you can't sell to your neighbour. Everybody there has to sign up with an IPP, and if you have any embedded generation you may only sell back to that IPP. 

This makes sense. We don't want cables bearing 230 V AC running over garden walls.

Apologies if I'm taking your post too literally.

PS: The resell tariff in the UK is not fixed by law, other than that it must be greater than zero.

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Guest Sarel

A couple of things to consider before we get to excited:

This is directly from a document here Eskom, if you connect to the Eskom grid directly:

Eskom will allow wheeling of energy subject to conditions…..

  • Wheeling subject to NERSA approvals
  • Licensing, registration etc
  • Connection subject to NERSA approvals and signing of a connection and use of system agreement
  • The account(s) will be adjusted in terms of Eskom’s policy on the reconciliation of accounts
  • The third party access will be implemented initially up to an overall limit of 300 MW and the capacity of a NEG will not exceed 300 MW (currently being revised).
  • A generator will not connect at low-voltage (<1 kV)

Also this, due to there not being a single standard across Municipalities, this is from a document here that Municipalities will use: 

3.3. All generators shall be nett customers All SSEG installations shall consume more energy than they produce over a consecutive 12-month period.

 

And from our Electricity Act 2007:

190981168_Screenshot2021-08-05at18_02_04.thumb.png.5cefcfefdd5485d0102df9edc5c14374.png

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On 2021/08/04 at 12:15 AM, Achmat said:

Looking at some of the pv graphs on this thread I would estimate that between ¼ to ⅓ of residential pv is lost due to panels sitting idle after batteries are fully charged and loads are taken care of. How much MW that is I have no idea as there's very little data on what's currently installed in the residential market. 

My own 10kwp will sit idle from around 12:00 when batteries are full and only needing to supply 1kw to 2kw for the loads. 

Hi.

 

This is the exact reason why I designed and built my system with two PV arrays of 12 panels each covering a wider spectrum of daylight hour exposure with two sets of batteries, each with it's own inverter. Once the first set getting morning sun is full, it will swith ocer and charge the second via domestic grid and solar. Though my harvesting is greater I still have extra PV capacity to mine during the day, so I will expand with more batteries.

Even during the worst winter conditions I have not had any outage at all. The trick lies in my own designed "Frankenstein" Arduino controlled changeover system and a decent inverter ensuring no interruption during changeovers. 

SA gets a lot more useable sun than people realise

Regards

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I have connected my Sunsynk auxilliary ourput to heat up my geyser as soon as the batteries are full and the PVs are generating more than 400W. This helps a great deal with idle time and keeps my geyser nice and hot. The same can be done with aircons on the grid side, if your Inverter can handle it. I have installed an 8KVa which can handle the amps easily.

 

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22 hours ago, TonyH said:

I have connected my Sunsynk auxilliary ourput to heat up my geyser as soon as the batteries are full and the PVs are generating more than 400W. This helps a great deal with idle time and keeps my geyser nice and hot. The same can be done with aircons on the grid side, if your Inverter can handle it. I have installed an 8KVa which can handle the amps easily.

 

The marvellous part of my system is at the moment at 12h20 all the PylonTech and also the AGM batteries are full. Then once I get the alert, washing and tumble drying can start. No load on the batteries as demand is now supplied via PV and around 17h45 the Li-Ion batteries will kick back in. This means that effectively the AGM battery system works for around 4 hours a day, supplying the household and once full, adding extra amps to the PylonTechs. They rest for 24 hours. The PylonTechs will work from 17h45 up to 9 tomorrow when the cycle starts over.

This is depending on available PV yield. I have on cloudy days had this change only happen around 14h00 but to me this means the AGM batteries will last a long time, not being overworked.

Something I never even realised is that the change happens depending on PV availability 1st and then state of charge. As this is dynamic it happens witout intervention. 

Truly automated.

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As is evident, washing and drying puts quite a load on the system but this is temporary and the batteries are not overworked.

Any battery depletion will be topped up as soon as the timers on the laundry equipment reaches stop stage.

With ample harvestable sunlight remaining, I never run out of electricity supply as the two banks are suitably sized.

One major learning curve for everyone in the house was to understand and manage loads. Pointless having an automated system that can function effectively with no discipline from people. They are all aware how to keep an eye out for the times when extra loads are forbidden. I enforce this rule quite strict.

Even while the load is quite high, the PV supplies the bulk of the load. The balance comes from the batteries. Once this cycle stops, the batteries will be topped up in minutes. The battery usage is thus very small

image_2021-08-13_130602.png

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On 2021/08/12 at 2:06 PM, TonyH said:

I have connected my Sunsynk auxilliary ourput to heat up my geyser as soon as the batteries are full and the PVs are generating more than 400W. This helps a great deal with idle time and keeps my geyser nice and hot. The same can be done with aircons on the grid side, if your Inverter can handle it. I have installed an 8KVa which can handle the amps easily.

 

@TonyH, when operating the AUX Smart Load, if the soc or pv drops below the cut off, the Smart Load switches off, but if the soc and pv ramp up again, does the Smart Load switch on again ??, does not switch on automatically for me

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Yes it switches on automatically. On my system if the battery is 99% and I have 400W or more generating from the PV's, the geyser heats up. I need to add that at 95% battery the AUX will switch off power to the geyser. On a hot day the aux switches on two or three times.

Edited by TonyH
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  • 4 weeks later...
On 2021/08/03 at 8:41 PM, Erastus said:

Interesting the concept now starting to take shape in SA means that soon I will be allowed to sell to my neighbor and don't have to sell to COCT or buy from my neighbor.

Thus I can sell my excess @ let say R 1.20 and do not have to sell to a munic or Esdom.

Also means I will be able to buy from any generation connected to the grid.

Pretty much how USA & UK ... works.  Ever wonder why Esdom created a third leg called distribution or networking.  For this very reason.

That is is CoCT does not cancel your approval in the meantime.

They have become notorious by doing this recently.

 

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On 2021/08/03 at 5:15 PM, Achmat said:

Looking at some of the pv graphs on this thread I would estimate that between ¼ to ⅓ of residential pv is lost due to panels sitting idle after batteries are fully charged and loads are taken care of. How much MW that is I have no idea as there's very little data on what's currently installed in the residential market. 

My own 10kwp will sit idle from around 12:00 when batteries are full and only needing to supply 1kw to 2kw for the loads. 

That’s very coincidental. My 10KW system also charges the batteries by 12 noon and after that we desperately try to use the excess power washing and drying clothes plus running a split AC in the bedroom all day.  I still see that about 33% of the power still goes to waste.

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  • 4 weeks later...
On 2021/09/10 at 10:12 AM, dreadlk said:

That’s very coincidental. My 10KW system also charges the batteries by 12 noon and after that we desperately try to use the excess power washing and drying clothes plus running a split AC in the bedroom all day.  I still see that about 33% of the power still goes to waste.

I don't really care too much about the power that still goes to waste, as I also initially attempted to harvest that. I soon enough realised the only way to do that would be through adding more storage, and that does not make economic sense to me. So I have made peace with that fact.

Yet our two approaches are quite similar. In my case all I have done is to limit consumption from batteries and to maximise consumption from the excess PV wattage once the batteries are full. This approach does seem to be advantageous.

At some stage the AGM batteries will have to be replaced, and only then will I bother to add something longer lasting. Hopefully the current trend of renewables getting cheaper will continue but our ever-weakening currency unfortunately does add a curved ball.

One last point. We have become so focused on efficiency that I manage to get our two battery packs full by 10h30 at the moment. This obviously depends on the quality of the daily yield.

Regards

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I include below two images. The ist was taken at 22h15 last night and showed that the batteries were on 83%.

The second was taken at 06h15 this morning and the SOC was 78%

You'll notice the efficiency of my household all with low energy devices, etc. Note that this includes running 3 refrigerators one of which is on a timer and shuts down for 4 hours in the middle of the night. That's in my bar, a normal sized upright Kelvinator that keeps my beer cold.

image.thumb.png.6c2638562d17f13359cd83dfc5a6f52b.png

 image.thumb.png.326b90cd4c9d8ed9b0da97d6cc5c3f5e.png

Note that at the time of this, all 3 refridgerators were turned on. We seldom exceed more than 700W at any given moment.

Regards

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On 2021/10/02 at 11:52 PM, Sass said:

I don't really care too much about the power that still goes to waste, as I also initially attempted to harvest that. I soon enough realised the only way to do that would be through adding more storage, and that does not make economic sense to me. So I have made peace with that fact.

Yet our two approaches are quite similar. In my case all I have done is to limit consumption from batteries and to maximise consumption from the excess PV wattage once the batteries are full. This approach does seem to be advantageous.

At some stage the AGM batteries will have to be replaced, and only then will I bother to add something longer lasting. Hopefully the current trend of renewables getting cheaper will continue but our ever-weakening currency unfortunately does add a curved ball.

One last point. We have become so focused on efficiency that I manage to get our two battery packs full by 10h30 at the moment. This obviously depends on the quality of the daily yield.

Regards

I highly suggest saving your money for batteries in USD so as to keep ahead of local inflation and devaluation. That is what I did over a period of years until I had enough to buy the whole system.  I use LifePO4 batteries and they can go from 100% to 20% SOC at night but there is still a gap I put in my usage time when I am on the grid between 5:30pm and 11pm.  Due to the possibility of late night power outages I would rather keep the energy in reserve until it's time to go to bed.

I can also get my batteries near full capacity by 11am in the summer, I have only had the system running since August so I missed out on the peak months of April through July. I suspect that I can get them charged even faster then.

I have been thinking about cheap ways to utilize more power like building some of my own battery packs but I am not all that confident in the cheaper cells that they sell out of China.

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On 2021/10/07 at 11:30 PM, Sass said:

I include below two images. The ist was taken at 22h15 last night and showed that the batteries were on 83%.

The second was taken at 06h15 this morning and the SOC was 78%

You'll notice the efficiency of my household all with low energy devices, etc. Note that this includes running 3 refrigerators one of which is on a timer and shuts down for 4 hours in the middle of the night. That's in my bar, a normal sized upright Kelvinator that keeps my beer cold.

image.thumb.png.6c2638562d17f13359cd83dfc5a6f52b.png

 image.thumb.png.326b90cd4c9d8ed9b0da97d6cc5c3f5e.png

Note that at the time of this, all 3 refridgerators were turned on. We seldom exceed more than 700W at any given moment.

Regards

 

I wish I was only using 700W of power.  I am using about 2.4KWh almost all day.  Before I got the PV it was at about 1.4KWh in the daytime but since we have all this excess PV I just let the ACs run if the Sun is out.  It saves on battery power at night as the place is already cool.

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