1 Inverter both DC and AC voltage

[VWLove]

I'm working on a project in which a relay is hooked up to your home grid and also a battery that is charged by a solar panel. The idea in theory is if your grid is compromised due to a power outage the dpdt relay will switch over and allow your device to be powered by the battery. Here is the problem; weve bought a dc to ac power inverter with 2 ac outlets and a usb port. We want to be able to tie the main grids ac voltage to the outlets as well as the dc voltage from the battery. Is this possible using that single inverter?

Our suggested proposal is to drill a small hole in the outside case of the inverter then solder the main a wire from the relay to the outlets of the inverter. Basically bypass all the internal components of inverter and use only it's outlets for the main power part of the circuit. a 12 battery will be hooked up to the input of the inverter in which the dc to ac conversion will occur and be outputted through the inverters outlet. The relay will only switch over to batter power when the main power cuts off therefore the inverters outlets will only be fed through one source at all times.

Is this a solid design? Any input is greatly appreciated.

 

[Diver300]

Aren't you just wanting a UPS (Uninterruptible Power Supply) ?

 

[blueroomelectronics]

Better yet buy a Grid Tie Inverter.

 

[crutschow]

You want to switch between the inverter output and the main's output with the relay, not just turning the mains on and off as you apparently want to do. It's not good practice to parallel the mains with the inverter output.


It probably would be best to build a separate outlet box to house the relay and just plug the box into the mains and the inverter box. Connect the mains plug to one pair of the relay contacts and the inverter plug to the other contacts. The output socket is connected to the relay wipers.

 

[tcmtech]

Aren't you just wanting a UPS (Uninterruptible Power Supply) ?

Thats what I got out of the discription as well.

 

[VWLove]

Well, first off thankyou everyone for the quick responses! I've finally found a forum with active members that offer up solid ideas and input!

In many ways I think what were working on is a ghetto UPS, but from my understanding of how a UPS works there is no input to allow charging of the battery from a secondary source besides main power?

I like Carl's idea of building a relay outlet box but I still don't fully understand; 1 outlet will be for main grid power and the other outlet for battery power coming out of the inverter.

Also, I didn't know what a grid tie inverter was until posting! They look great and already have my mind wandering how to incorporate one into my next project.

Thanks again

 

[tcmtech]

I've finally found a forum with active members that offer up solid ideas and input!

Really? Please do tell us where this place of mystery and wonder is so that we too can go there!

In many ways I think what were working on is a ghetto UPS, but from my understanding of how a UPS works there is no input to allow charging of the battery from a secondary source besides main power?

Most typical UPS units use common lead acid batteries in the 12 or 24 volt setup which make adapting them to use a much larger external battery setup with its own dedicated charging system not a big issue. I have done that to a number of them over the years when the internal battery's went bad. Why spend over $100 on a 12 volt 10 Ah battery when you can buy a 12 volt 100 Ah deep cycle marine battery for less and get ten times the run time out of it.

I didn't know what a grid tie inverter was until posting! They look great and already have my mind wandering how to incorporate one into my next project.

If you have not already done so check out the Renewable Energy section and AE subsection in that for the DIY Grid Tie Inverter threads. Rumor has it you may even see me there from time to time.