Nice, so you could actually illegally connect that. But I'm sure after a few readings they will figure out what is going on...
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Solar Power Thread
- Thread starter empirex
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Nice, so you could actually illegally connect that. But I'm sure after a few readings they will figure out what is going on...
wetkit
Expert Member
A 3kw grid tie invertor will only be able to feed 3kw into the power system, if you drawing 6kw from Eksdom or not.
The kw rating only bacomes important with off grid, Bi-directional and Hybrid systems.
The kw rating only bacomes important with off grid, Bi-directional and Hybrid systems.
Hmm so you would still be able to pull say 10kW even though have have for instance a 3kW grid tie installed? This does make things simpler, because it would suck if you were limited to the grid tie inverter ratings...
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Arthur
Honorary Master
Just make sure your grid-tied equipment is up to spec for things like islanding. It must automatically disconnect from the grid when the grid is de-energised, for obvious safety reasons.
Another expensive lesson I learned is to ensure property lightning protection. About a year ago I had a lightning strike on the mains cable (which is aerial) and it blew my inverter. Large spikes through the mains power are not uncommon, especially on the Reef (though I am now in the Little Karoo). Decent lightning protection for both the inverter (via mains) as well as the panels (on DC circuit) is VERY expensive. I now have DEHN DG S 150 arrestors on the AC input and output lines, and also between the inverter and the three MPPTs on the DC lines.
Another expensive lesson I learned is to ensure property lightning protection. About a year ago I had a lightning strike on the mains cable (which is aerial) and it blew my inverter. Large spikes through the mains power are not uncommon, especially on the Reef (though I am now in the Little Karoo). Decent lightning protection for both the inverter (via mains) as well as the panels (on DC circuit) is VERY expensive. I now have DEHN DG S 150 arrestors on the AC input and output lines, and also between the inverter and the three MPPTs on the DC lines.
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What sort of solution for protection did you come up with? And how much was it in the end?
Arthur
Honorary Master
More info in edited post above.
The Dehn arrestors are around R900 each. They are single pole, so depending on your system you'll need 5 minimum. Plus of course the cabling. And extra mini-DB if your current one is full. And labour.
The Dehn arrestors are around R900 each. They are single pole, so depending on your system you'll need 5 minimum. Plus of course the cabling. And extra mini-DB if your current one is full. And labour.
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Arthur
Honorary Master
It depends on the inverter. Many cheapies cap your draw peak to the inverter max.
Any suggestions on ones that do not limit you in such a way?
Arthur
Honorary Master
I haven't looked at this in over four years, so don't know what's out there now.
I have an MLT Drives Power Star 12kW on single phase. It handles double its rating
Awesome inverter, it can pretty much do everything, except PV array input. I'm looking at the 6kW unit. Which can handle loads up to 12kW when there is an AC power source.
Arthur
Honorary Master
It does do PV array input. At least my model does - Power Star II 12kW.
Yes the bigger ones have that built in.
Ps...We being load shed right now... until 8PM.
itareanlnotani
Executive Member
FYI - I have a website describing my evil exploits in the solar realm here - http://www.goingsolar.co.za
May be worth reading it, as I explain stuff in there. I occasionally update it too
Note that feedback into CoCT is illegal unless you are on their special solar tariff and have a 4 quadrant meter, and have filled in the SSEG paperwork, and have been approved for said paperwork, and then and only then will they credit you for what you use, maybe, but only if they're feeling generous and you've used more than you've generated. Its such a great deal!*
As you can tell I'm not very impressed with them, with regards to that.
*Apparently it works out if you spend > R2500 a month, and don't feed back.
eg If monthly bill > R2500, buy one panel, sign up for their SSEG rate, then its worthwhile.
Otherwise, not really.
May be worth reading it, as I explain stuff in there. I occasionally update it too
Note that feedback into CoCT is illegal unless you are on their special solar tariff and have a 4 quadrant meter, and have filled in the SSEG paperwork, and have been approved for said paperwork, and then and only then will they credit you for what you use, maybe, but only if they're feeling generous and you've used more than you've generated. Its such a great deal!*
As you can tell I'm not very impressed with them, with regards to that.
*Apparently it works out if you spend > R2500 a month, and don't feed back.
eg If monthly bill > R2500, buy one panel, sign up for their SSEG rate, then its worthwhile.
Otherwise, not really.
AchmatK
Honorary Master
Found this online calculator to determine what your saving will be based on your location, direction of panels, elevation angle, etc. It is US based so the amounts come back in $ and the closest weather station data they use is in Harare.
I put in some figures based on the 4kw MPPT inverter on the the power store website and 18 x 235w panels. My average monthly saving would work out to about R900. I may have been out with some of my inputs but this would not impact the final figure significantly.
http://pvwatts.nrel.gov/pvwatts.php
Maybe those with an existing system can input their figures and see how close the estimates are to their actuals.
I put in some figures based on the 4kw MPPT inverter on the the power store website and 18 x 235w panels. My average monthly saving would work out to about R900. I may have been out with some of my inputs but this would not impact the final figure significantly.
http://pvwatts.nrel.gov/pvwatts.php
Maybe those with an existing system can input their figures and see how close the estimates are to their actuals.
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itareanlnotani
Executive Member
Some math on viability for you based off of my averages - I posted this elsewhere.
http://mybroadband.co.za/vb/showthr...-long-term?p=14126243&viewfull=1#post14126243
Don't forget to cater in losses, panels are cheap compared to other components, so better to have more of those if you can.
Panels are not 100% efficient. (cable losses etc, shading bla bla, say 80% of actual to be safe for peak values).
Inverters are not 100% efficient (PV ones are close to 98% though)
Battery power in/out is about 70% efficient.
http://mybroadband.co.za/vb/showthr...-long-term?p=14126243&viewfull=1#post14126243
Don't forget to cater in losses, panels are cheap compared to other components, so better to have more of those if you can.
Panels are not 100% efficient. (cable losses etc, shading bla bla, say 80% of actual to be safe for peak values).
Inverters are not 100% efficient (PV ones are close to 98% though)
Battery power in/out is about 70% efficient.
I was wondering has anyone used http://www.renesola.za.com/ ? They seem to be well priced. I'm just still trying to figure out how it all works.
They have a warehouse in Durban. Also the have two trade terms EXW and DDP. What are the differences? EXW : You are responsible for the shipping from their warehouse to your address and DDP they are responsible?
Prices range from R7.2/W. Are these prices ex.VAT, must be?
I suspect you would also need to deal with Customs? Or does the DDP take care of that?
They have a warehouse in Durban. Also the have two trade terms EXW and DDP. What are the differences? EXW : You are responsible for the shipping from their warehouse to your address and DDP they are responsible?
Prices range from R7.2/W. Are these prices ex.VAT, must be?
I suspect you would also need to deal with Customs? Or does the DDP take care of that?
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lucifir
Expert Member
anyone use nickel iron batteries??
I read somewhere that they the best for this type of scenario, but from reading this thread I don't recall anyone using them, and was wondering why not??
I read somewhere that they the best for this type of scenario, but from reading this thread I don't recall anyone using them, and was wondering why not??
itareanlnotani
Executive Member
DDP = Delivery Duty Paid.
EXW = Ex works. eg all costs paid by you.
EXW = Ex works. eg all costs paid by you.
So DDP is then better I suppose? Wonder if they would still ship to your address. At those prices I must say it's tempting. The local pricing is just so much more.
One would need to calculate the actual R/W when shipping and insurance is included though. But it might still work out cheaper.
By this definition it sounds like they would be responsible for all shipping and costs? Doesn't make much sense to me since it seems too cheap if shipping would be included then.
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