AEVA Members: your Forum Login (here) is NOT the same as your new AEVA member login.
You do not need to change your existing Forum login.

Pairing up a battery inverter with a grid tie inverter...

How do you store and manage your electricity?
Post Reply
User avatar
jonescg
Senior Member
Posts: 3368
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Pairing up a battery inverter with a grid tie inverter...

Post by jonescg »

Here's a quirky (and probably dumb) idea suggested by someone on the internet:

Take a grid tie inverter and power it with a 2 kW array, for example.

Take a 3 kW DC-AC inverter powered by a 10 kWh battery.

Parallel the AC outputs of both inverters, protected and switched, of course.

Turn on the Battery inverter and start supplying a load.

Turn on the grid feed inverter.

Presumably if the PV/Gridtie inverter voltage exceeds that of the DC/AC inverter, current will flow back to the battery?

I can see a few problems with overcharge...
AEVA National Secretary, WA branch chair.

User avatar
Richo
Senior Member
Posts: 3737
Joined: Mon, 16 Jun 2008, 00:19
Real Name: Richard
Location: Perth, WA

Re: Pairing up a battery inverter with a grid tie inverter...

Post by Richo »

The DC/AC inverter probably has polarity protection on the battery side preventing the grid tie from feeding power into the 10kWh battery.
My guess is the grid tie will bump up the AC voltage until it hits it's maximum AC output threshold, shuts down and reports an error.
Likely will happen within a few secs.
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

User avatar
jonescg
Senior Member
Posts: 3368
Joined: Thu, 21 Jan 2010, 23:05
Real Name: Chris Jones
Location: Perth, WA.

Re: Pairing up a battery inverter with a grid tie inverter...

Post by jonescg »

https://www.youtube.com/watch?v=F1q5uIzjj_M&t=391s

This is where he's coming from I think. Perhaps he didn't specify that the inverter needed to be an inverter / charger? Presumably the one with the transformer built in?
AEVA National Secretary, WA branch chair.

User avatar
weber
Site Admin
Posts: 2746
Joined: Fri, 23 Jan 2009, 17:27
Real Name: Dave Keenan
Location: Brisbane
Contact:

Re: Pairing up a battery inverter with a grid tie inverter...

Post by weber »

This can be done, and is referred to as "AC-coupling" your PV array (Google it). And yes, the battery inverter certainly has to have been designed as an inverter/charger. Whether it works or not depends strongly on details of the implementation of the two inverters -- details which are not usually given in their specs and are not easy to find out, unless the manufacturers specifically say that they have been tested or designed to work together in this manner, and it usually requires a communications link between the two inverters to do it properly. An example is the Kaco grid-feed inverter and the Selectronic SP PRO battery inverter.
One of the fathers of MeXy the electric MX-5, along with Coulomb and Newton (Jeff Owen).

Post Reply