[RE-wrenches] Discharging a high voltage battery

[August Goers]

Hi Larry,



I have no idea what would happen if you connected a DC high voltage (340 v)
battery source to a PV inverter. I guess my point is that it isn’t designed
for it and likely wouldn’t work. Maybe it would? I have to think that both
the inverter and the EV would have some sort of logic or circuitry to
prevent the inverter from just pulling juice from the battery. Regardless,
the inverter wouldn’t have the controls setup to decide when to start
inverting and when to stop.



Technically, you might be right though – the MPPT circuit on the inverter
might just sweep and invert.



August



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Starlight Solar Power Systems
*Sent:* Thursday, February 23, 2017 3:14 PM
*To:* RE-wrenches
*Subject:* Re: [RE-wrenches] Discharging a high voltage battery



Hello August,



Help me understand your point. If the MPPT circuit is sweeping, it will see
the same voltage everywhere. Would it not just continue sweeping because it
can’t lock on? Or perhaps it times out? As long as it is producing power
during that process, won’t it be fine?



Thanks to all for the responses.



Larry







On Feb 22, 2017, at 1:04 PM, August Goers <august at luminalt.com> wrote:



Larry –



My immediate thought is that you would need a listed grid tied inverter
designed for the purpose of connecting to this type of battery and
inverting to the grid. A regular PV inverter won’t cut it since it is
designed to MPT PV modules.



The SolarEdge StorEdge product sounds like the closest thing on the market
that might be close to working. But, once again, it needs to be setup to
work with your particular battery. I think StorEdge is planning on working
with Tesla and LG Chem RESU batteries in the 350 to 400 v range.



August



*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *Starlight Solar Power Systems
*Sent:* Wednesday, February 22, 2017 11:17 AM
*To:* RE-wrenches
*Subject:* [RE-wrenches] Discharging a high voltage battery



Hello Wrenches,



Someone has asked me about discharging their EV battery into the grid. They
have an existing grit tie system. What they want to do is connect a 5kW
grid tie inverter to their 340 volt, 32kWh EV battery bank and feed the
grid to discharge the battery. Why was not discussed but sure bugs me.



My uneducated guess is the inverter will be immediately damaged. My thought
is how would it limit the input current? Or, is there such an inverter
available that can do the job?



Any input is appreciated.


Larry Crutcher
Starlight Solar Power Systems







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