How to combine solar & wind with xantrex 4048
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I would like to add modest solar and perhaps wind charging to my 48vdc battery bank which is interfaced with Xantrex SW4048 and LPG generator. What is the best strategy for giving charging priority to solar/wind over the grid powered charger in the inverter? Is it even possible? Many thanks.
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I assume that this is a true Grid Tied operation (Electric Utility)? Will you have net metering (sell back to the utility)?
The solar/wind will be fed back to the grid during normal operation and the gen+solar+wind will be for backup power?
Anytime the solar or wind try to push the battery voltage higher then the SW charger settings, the SW will try to drag down the voltage to its setting resulting in excess power to be sucked off and supplied to ACout load.
Solar and wind controllers are set to a slightly higher absorb and float voltage levels then the absorb and float voltage settings on the SW4048. (about 0.2-0.4 vdc higher).
If any of the three charge contributors do not have temp compensation then none of the three should have temp compensation.
When battery is discharged the SW will contribute to the battery charging. You can set the maximum charge AC current setting on the SW to a low level to minimize its contribution.
Now for the legal note. If the ACout load can not absorb the excess power the SW will push to grid and actually show a negative number on the ACinput/Charger input current meter reading in menu 4. Depending on your utility meter type, you may actually see the wheel turn backwards. It is not legal to push to grid unless there is a grid tie adaptor (GTI box) and approved permit to do so. SW's produced after mid-2005 have the GTI control interface. They also have a UL1741 designation label on the left side of the unit.
Wow! Thanks for the swift replies. No, I do not use grid tie (I have ver 2.4 software but SELL is OFF). Dwelling is passive solar, earth sheltered with AB PLC automation of all switches, loads, etc.. The SW4048 serves as whole-house UPS with seamless switching to/from grid of essential loads during outages. I was looking for a strategy to allow me to migrate from grid/generator charge maintenance to wind/solar. Sounds like I need to consider revolution instead of evolution, perhaps installing larger array to serve as primary for some part of my electric consumption (for example, switch my 48 VDC lighting powered from battery bank whose charge is maintained by the SW4048 to a parallel photovoltaic system.) I will continue to look for alternatives! Thanks again.
Does your utility support Net Metered power (many smaller ones do not)?
Grid tied is the ideal way to go... The most energy efficient and will allow your batteries the longest life (basically, float charging until they are needed for emergency power).
Otherwise, treat it as an off-grid system and design your primary renewable power (solar/wind/etc.).
One of the issues with running from your battery bank is that cycling your batteries will reduce their life and cost you more than grid tied operation.
If you want to run without Grid Tied (Sell turned off)--I believe the XW has the capability to supply power to your loads without feeding back to the grid--But reading the manual and help from other here that know more than I can help you with your configuration.