IMHO, the batteries are the real skeleton in the closet here. Sooner or later they're gonna poop. at 2400 Ah you're likely running a multi string set up, so it's likely someone's number is already on the board. Even if you set the FX down to a trickle charge or use some kind of contactor to fake the FX into thinking the grid is really a gen set, sooner or later the batteries will fail. Better to design for it now.. Besides, Rather than regulating solar input to protect batteries, You're better off selling (Storing) power on the grid. Depending on the age of the batteries or the competence of the operator (Home Owner), I'd either swap out the FXs for a GVFX (and down size the batteries when they puke), or loose the current setup all together and go for a batteryless Grid Tie inverter. (and maybe keep the current setup as a whole house UPS.. until the batteries poop). Again, depending on the customer, you might milk these batteries by setting up individual strings on an isolation switch (like in the marine industry), at least this way you can referee. Good Luck. db
Dan Brown
Foxfire Energy Corp.
Renewable Energy Systems
(802)-483-2564
www.Foxfire-Energy.com
NABCEP #092907-44
-------- Original Message --------
Subject: [RE-wrenches] Off-Grid to Grid-Connected -essential loads
From: benn kilburn <[email protected]>
Date: Fri, May 04, 2012 5:08 pm
To: Wrenches <[email protected]>
Wrenches,I have an off-grid client who is going to be connecting to the grid. Since the system (~9 kW of PV and ~2400 Ah battery) is already well suited for the loads, I am wondering about the necessity of an essential loads panelboard. I'm not sure if I see the need since the battery is already sized for all the existing loads.The intent is to continue running all the loads from the battery and have the (Outback) settings so that the grid is only used when the PV isn't able to maintain a particular battery voltage setting.Comments, insights into this type of set-up?Thanks,bennDayStar Renewable Energy Inc.780-906-7807Certified Construction Electrician Solar Photovoltaic Systems CertifiedCertificate # 0007SHAVE A SUNNY DAY
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