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| Outback: FX2000: To Grid Tie or Not to Grid Tie... http://solar-guppy.com/forum/viewtopic.php?f=20&t=126 |
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| Author: | Christopher Freitas [ Fri Nov 15, 2002 2:38 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
Each FX2000 includes a AUX output control circuit which can be used as a AC load shed control system (there are several other modes you can select also). So the FX2000 can turn off all but a low power critical load circuit if the battery/capacitor/PV array output was not sufficient to power the entire AC loads. The MX60 display does show how much power in watts the PV array is producing so you will have an idea of the load able to be operated. The MX60 will be a necessary part of a battery or batteryless installation BTW. A couple of small sealed batteries might still be a better option if you wanted to operate a variety of AC loads or loads which operated intermittantly. |
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| Author: | Christopher Freitas [ Fri Nov 15, 2002 3:26 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
We actually did not have a PV array connected to the super caps when we started the compressor - we used only the stored energy. We did 5 starts (10 -15 seconds each) with the compressor tank fairly low of one charge. The peak start amps of the compressor was about 90 amps when plugged into the grid BTW (it was labeled as a 6hp motor...). I will get the details of the super caps for you soon. The amount of joules stored were not that high as we only charged them to 24 vdc and they were rated at 60 vdc or so... These are surge rated super caps - I have seen semi-truck engines using these to run the starters (42 vdc system) and they even did it in a cold temp test chamber (0F) already. Thats one hell of a surge.... |
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| Author: | Rob Larson [ Fri Nov 15, 2002 3:47 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
If the PV is producing 2000 watts, and the current load is 200 watts, what happens to the other 1800 watts? Do you need a dump load like is done with wind systems? If you operate the controller such that it only puts out 200 watts, do you know that it could ramp up to 2000 watts if the load changed? Without the infinite load of the grid, or the predictable load of a battery, this seems like a problem. I remember reading about a European grid-tie inverter that located the MPPT point by disabling the array for about 1/10 second, and watching what voltage the array went to. The MPPT point was then identified as a percentage (83% or so) of the open circuit voltage. Not precise, but a simple to calculate and reasonably accurate approximation. |
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| Author: | Christopher Freitas [ Fri Nov 15, 2002 9:00 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
The MX60 allows the PV array voltage to rise if the load is less than the capability of the PV array. This is often called going "off peak" and is a very nice way to reduce the PV array power (I once saw a charge controller that turned the PV array away from the sun to regulate the charging of the battery... work well - until it got stuck). The MX60 can respond very quickly - but some testing and further development will be needed to maximize the performance of this type of application. The MPPT method discribed of checking the open circuit voltage and the operating at a ratio or offset amount is not a new idea. This essentially is what the RV Solar product Solar Boost does (and rick was able to get a patent on just a year or two ago even though much prior art exists ...). We decided to use a microcontroller instead to find the actual peak power point by active means. This is much more complicated and more expensive - but - it can result in a little more output by finding the optimal point instead of using a close approximation. One or two percent more output power can be worth a lot. Using an active method also works better when there are issues of partial shading or PV module degradation which changes the ratio of peak power to the open circuit voltage. [img]images/smiles/icon_cool.gif[/img] |
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| Author: | Rob Larson [ Sat Nov 16, 2002 2:56 am GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
So it sounds like a batteryless system is not only possible but well along in development. I look forward to its availability. |
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| Author: | Christopher Freitas [ Sun Nov 17, 2002 1:24 am GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
Sssshhhh... we don't want the other guys to know... [img]images/smiles/icon_wink.gif[/img] |
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| Author: | Frank [ Thu Nov 21, 2002 7:44 pm GMT EstGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
<BLOCKQUOTE><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><HR>Originally posted by Christopher Freitas: Each FX2000 includes a AUX output control circuit which can be used as a AC load shed control system (there are several other modes you can select also). So the FX2000 can turn off all but a low power critical load circuit if the battery/capacitor/PV array output was not sufficient to power the entire AC loads. <HR></BLOCKQUOTE> I don't know much about these systems, but it seems that this is a logical means of handling the problem. Loads could be dropped off in a prioritized fashion and the same logic could be used to add them back. Why couldn't this approach be used to run a load at night from batteries as long as possible, then switch back to grid when a predetermined point was reached? (Or is this already done?) thanks |
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| Author: | jdesoto [ Mon Nov 25, 2002 8:37 am GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
When will the MX60 be released? Thanks, Joaquin |
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| Author: | bob [ Wed Nov 27, 2002 5:50 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
>>When will the MX60 be released? Thanks, Joaquin We have been shipping limited quantities of the MX60 for the past week or so. Hopefuly the quantities will be bigger very soon. thanks ! boB Gudgel OutBack Power Systems [img]images/smiles/icon_wink.gif[/img] |
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| Author: | jdesoto [ Fri Dec 13, 2002 6:17 pm GMT EthGMT ] |
| Post subject: | FX2000: To Grid Tie or Not to Grid Tie... |
Thanks, I have 2 on order but I guess I haven't made it to the top of the stack. |
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