Dual PS1 vs PS2 Install Outdoors (Enclosure Needed)?!

Discussion about OutBacks "PS" enclosures

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Dual PS1 vs PS2 Install Outdoors (Enclosure Needed)?!

Post by GSachs »

Hello Chris & the Outback Team,

Please keep up the good work - your reputation is well deserved - and you are leading this industry!

In summary, we must decide between the use of two PS1's vs using a PS2 within an outdoor rated enclosure. We have carefully evaluated all alternatives in desiging this system. Based on the size of the desired array and for numerous other reasons we must use two 3600 watt inverters and the only viable installation location is oudoors.

Certainly, this brings up a variety of issues and questions. We live just outside NYC and acknowledge concerns about freezing batteries at low charge, and ensuring the enclosure is properly ventilated. I welcome other concerns, but my primary questions are as follows...

1. TWO PS1's vs ONE PS2? What do you see are the primary issues pertaining to the use of two PS1's vs using one PS2? As I inspect the wiring diagram of the PS2 Grid-Tied wiring diagram ("ps2ac-dcsystem48vGT.pdf") I see 2 major issues: (a) The bypass interlock would only pertain to one inverter at a time.. Is this a big issue? I can still use the mate to program out of phase operation correct? (b) Can I still maintain a common battery bank? In other words, what would the adverse effects of connecting the positives of each PS1 bank together?

2. Of course, the second option is to install a PS2 outdoors and enclosing it in a pre-fab or custom enclosure. CAN YOU SUGGEST ENCLOSURE MANUFACTURERS or POC's? If not, we would need to build a custom enclosure around the PS2. But then the issue is that we would not be able to officially rate it NEMA-3R; it would likely be made from wood; and this may not fly with local code officials, etc...

Bottom line is, which would you/your engineers suggest based on technical issues and/or other issues? Other factors: Total price of each both options; whether the code official will allow us to build a custom enclosure; etc...

Again, thank you very much for your time, consideration, and leadership. I also thank you for your support in the Solar-Decathlon and our Solar-H2 home - we are still moving forward with this project. Please don't hesitate to ask any more questions. I look forward to the future of Outback.

Yours, Gregory
Technical Advisor, EmPowerCES

Post by Christopher »

We have had installations done with both two PS1 systems and one PS2 system with a custom built enclosure. It mostly depends on how strict your local inspector is on what qualifies as an outdoor enclosure. I know of customers who effectively built an outside "closet" in which the equipment was installed - and had no issues with the building department. I have even seen the small tool type sheds used with success.

If you go the dual PS1 approach you need to remove the HUB4 from one enclosure and route the CAT5 cables from the inverter and controller to the other enclosure. Then program one unit (the one plugged into port 2 of the HUB4) to be a "Classic Slave".

Having a pair of them on the same battery is not an issue when they are stacked - and it can be done even with them both programmed as masters. The two separate input - output - bypasses are not ideal, but there is not really any issue with them from a code standpoint from what I can tell.

Its difficult to find an enclosure big enough for the PS2 system - they are also expensive (about $1000) and have to ship by a truck. I typically buy cabinets like this from a company called "circle AW" which has plants around the USA.

Thanks for the supportive comments!

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