Manual switch to separate power from panels from on inverter to another

[mrestimator]

A low cost way to manually temporarily switch over from a grid-tied system to off grid without sending power to grid.

I want to be knowledgeable before I have an electrician handle this. I have a 2.4 K solar panel system of 10 panels and an inverter to a grid-tied system. Because the power very infrequently goes out and lasts less than a day, I would like to manually switch and divert the the feed coming down into the grid inverter, into a small backup 120 volt inverter connected to an 20 amp outlet box. I can run extension cords to freezer and refrigerator.

It should be safe to anyone working on the grid even if I manually switch it back and forth since, if the grid power is off, once the manual switch sends the power to the grid inverter, that inverter is already set up not to send power to the grid unless it senses power from the grid.

This backup system will be much less expensive than replacing the current setup with a automatic AC coupling inverter or other non- automatic hardware.

If this is feasible, do I have to worry about the panels producing more power than I'm using? Could someone give me some insight on what hardware is needed?
Thanks

 

[KlausST]

Hi,

1) you need an inverter that is able to run in off grid mode (most of the inverters do not. Off grid inverters also don´t suffer from pushing too much energy to the load)
2) to be useful you need batteries
3) you need to follow safety regulations. Ask your grid operator.
4) you may need to use switching devices that are safety approved (forced contacts, wider contact spacing...), ask your grid operator.

Klaus

 

[D.A.(Tony)Stewart]

GTI’s with PV tend to cost more to have the ability to earn revenue by reversing power than simply a UPS with PV backup and no ability to earn revenue.

Payback period and MTBF will guide your choices of backup storage and benefits.

Logically your downtime costs must be weighed with service downtime and cost of equipment with storage options in Wh.

 

[BradtheRad]

We lived in a house where the breaker box had a manual change-over switch installed. It was the first thing seen by the thick wires coming out of the wall. It was a knife switch consisting of two thick copper bars on hinged ends and a handle. It looked just like the old-fashioned laboratory equipment seen in movies.

I guess your plan is similar. Three wires typically come from the street transformer (two live 120VAC wires and one neutral). These emerge from the floor or wall and go into a breaker box. The two live wires need sufficient slack so they can connect to the new switch which ought to be positioned close by. If space is tight then your electrician may say he needs to re-arrange the breaker-box in order to satisfy codes. Expense may rise for that reason.

Your home may be rated for 50A or 60 or 100 or 200 Ampere service. The electrician needs to select a switch big enough to match that rating. He may know how to evaluate your service capacity although you ought to know what it is ahead of time.

Our breaker box had a cable coming out of it, with a three-prong plug installed suitable for plugging into a generator. My family didn't have a generator but I had my backup power system consisting of solar panels, battery bank and power inverter. Experience with that let me get acquainted with using our garage change-over switch.

 

[mrestimator]

Thanks for the suggestions: Here's want I want to do: Manually switch to split the power coming from the 2Kw solar panels to either the current grid-inverter or to an (off grid inverter to a 20 amp outlet with extension cords to a freezer and refrigerator.)

Based on the response above, I think a electrician needs these parts in sequence order from the panel feed.

1. GE Baomain Universal Rotary Changeover Switch SZW26-63/D303.3 660V 63A 3 Position 3 Pole Phase + box amazon 70$
2. 3000W Solar Inverter Charger 24V to 120V, Pure Sine Wave Power Inverter 3000 watt Max.PV Input 4KW 450V, Built-in 80A MPPT Controller and fit for Lead Acid and Lithium Batteries – Amazon $480
3 Battery
I think these would do it but I’m opened to any suggestions.

Thanks

 

[dick_freebird]

Transfer switches, manual or automatic, are widely available
at a range of costs. I have an interlock kit on my Square D
panel, easy install, kinda clunky but it just sits there except
after hurricanes. Then I backfeed the panel through a 100A
breaker (generator breaker is 60A). Interlock "puzzle" just
enforces the either-or. Study one and you could copy it or
modify it to suit a two-position baby electrical panel. Think
I have also seen breaker duos with their switches mechanically
linked, so one goes off when (before) the other goes on.

I say go for an old timey knife switch. Young Frankenstein style.
You know you want to.