Multiple A/C Inputs??

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Dtt255
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Multiple A/C Inputs??

Post by Dtt255 » Sun Oct 11, 2015 5:52 pm

Hello All,

just had a grid down exercise and found some holes in my system and some ideas I wanted to know the answers to, if they were possible.

Right now I am grid interactive.

3 kw on the roof, which runs into the gvfx3648 and mx80 CC. DC side is connected to the T105, 48v battery bank also.

Grid supplements it all.

I have a genny hookup also, bu don't have it hooked up to the AC side of the GVFX.

Wanted to know a couple of thing that I am confused on.

Can the inverter accept AC input form different sources? (I assume NOT at the same time) So basically would I need some sort of 'switch' on my ac inputs to designate WHICH ac input is moving into the inverter?

Or does a genny go into the DC side? I assume not since it is AC power.

If an additional AC source goes into the AC source of the GVFX....I assume the inverter re-reoutes the power back OUT to the ac output loads. No further wiring needed?

OR am I thinking this all wrong??

Does the GENNY just CHARGE the batteries and the batteries 'run' all the AC Loads? Does the inverter just take either the AC (genny) or DC (solar) input power and then just converts/re routes said power to batteries, THEN reroutes that powers to the loads?

Ugggg so confused!

I hope I am making this clear questions.

Thanks for ALL your help!

DTT

SandyP
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My RE system: 8 x 190W 24V Suntech panels (4 strings of 2) July 2011
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Mate2
Outback FM60 MPPT (max output lowered to 55amps)
12 x 2V Hoppecke GEL 660 Ah C100 - 24V System
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Victron BMV-602s
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Location: Victoria, Australia

Re: Multiple A/C Inputs??

Post by SandyP » Sun Oct 11, 2015 8:04 pm

Dtt255 wrote:
Does the GENNY just CHARGE the batteries and the batteries 'run' all the AC Loads? Does the inverter just take either the AC (genny) or DC (solar) input power and then just converts/re routes said power to batteries, THEN reroutes that powers to the loads?
AFAIK (in an off grid setting using the VFX), when using a genny as AC input the genny will power the AC loads via the VFX settings and also charge the batteries (if they require) based on the settings you have applied via the Mate. The VFX has settings to limit the total power drawn from the genny for combined AC loads and the battery charging - thus the higher the AC loads the less battery charging will occur if you are at the limit of the ac2/gen input limit.

From what I have seen, while using the genny, any DC solar input is added to the battery charging power provided by the genny. Thus caution is needed if you have set the rate of AC charging of your batteries (by the VFX charger) to the maximum recommended by the battery manufacturer and then the sun comes out and some DC solar charging occurs via the solar charge controller in addition to this!

In my case, after 4 days of very little sun, we started the genny and the Mate setting was for 6.0aac current (240V) which means 60adc for our 24V solar system this being around 10% charge rate of our batteries. When the sun came out on a partly cloudy day we saw an additional 30adc charging from the FM60 giving total charging of 90adc. The battery manufacturer states charge rates up to 20% of the battery capacity are allowed.

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Jorge Guzman
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My RE system: VFXR3524A, FM80, MATE3. 3x 260W REC. 4x Trojan L16 FLA 370Ah.
Location: Arlington, WA

Re: Multiple A/C Inputs??

Post by Jorge Guzman » Tue Oct 13, 2015 1:55 pm

Dtt255 wrote:Can the inverter accept AC input form different sources? (I assume NOT at the same time) So basically would I need some sort of 'switch' on my ac inputs to designate WHICH ac input is moving into the inverter?
This is correct, you will need an external transfer switch. It may be either manual or automatic.
Dtt255 wrote:Or does a genny go into the DC side? I assume not since it is AC power.
This is possible if the AC power is rectified into DC. Although it has its draw backs, It may be a solution you might consider. The GVFX inverter its not guarantee to charge from a dirty signal since it expects grid quality power.
Dtt255 wrote:If an additional AC source goes into the AC source of the GVFX....I assume the inverter re-reoutes the power back OUT to the ac output loads. No further wiring needed?
If i understood you correctly, having two sources coming in at the same time creates a phasing problem and may damage equipment so having an external transfer switch is a must.
Jorge Guzman
Sr. Strategic Platforms Analyst


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tallgirl
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My RE system: 16 Kyocera KC175GT (2,800 watts DC), MX-60, 2 OutBack GVFX3648, 8 GC2 batteries (6v @ 215AH),
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Re: Multiple A/C Inputs??

Post by tallgirl » Thu Dec 03, 2015 3:13 pm

The best solution to charging a grid-interactive system from a generator is to either use an inverter-generator, such as one of the Honda models that end in "i", or get a DC charger, such as one of the Iotas and attach it to the generator. This has the advantage, especially for folks with grid connections, that you can use a much smaller generator and not kill the generator when a huge load kicks in. People who live completely off-grid tend to have fewer of those monster loads.
Julie in Texas

I ride bicycles. A lot.

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