I purchased a SMA Sunny Boy 5.0-US-41 Inverter and brought it to the Philippines. Many connections in Manila are 2 Phase 120v. I am in the province, where we have Single Phase 220v. I called SMA tech support and they said the inverter will not work on Single Phase 220v. She said I could get a transformer to convert the Single Phase 220v to 2 120v lines and connect the Inverter that way. What kind of transformer do I need to output 2 lines of 120v? Is this possible?

I hope I can find a solution, as it would cost more to send the thing back than it would be to buy a new one. Thanks to anyone who can help!

  • Do you have an agreement with the power company to sell power back to them? Or are you hoping to wind your meter backwards and they won't know? Or is this for off-grid use when AC power goes down? Do you have a Tesla Powerwall or similar unit? Mar 31, 2022 at 8:50
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    @Harper-ReinstateUkraine I get the impresison that in the Philippines it's a bit of a free-for-all, which is also why their power grid is not particularly stable.
    – user253751
    Mar 31, 2022 at 9:56
  • No, the bureaucracy in this country would keep me from ever connecting this. I am planning to set export ac to 0, so when the grid goes down, everything stops. But one reason I bought this was for the 2000w of power you can switch on when the grid is off that produces ac power directly from the panels. This way I wont need a generator to keep my fridge cold. Mar 31, 2022 at 12:15

1 Answer 1


Obligatory disclaimer: this advice applies to OP's particular situation, and is not talking about grid-tie solar in general.

Wow, you sure spent a lot on the wrong thing.

Grid-tie isn't going to happen.

Your country uses AC power, right? AC power means the current moves in both directions, changing every 1/120 of a second (full cycle every 1/60). With me? Ignoring solar for now... the power you are buying flows in both directions because it's AC. So your average, common electric meter will of course charge you for both directions.

OK, let's add solar panels with a grid-tie inverter. Electricity doesn't store, and most of the time an average house has very little load (assuming water heater and A/C are cycled off at that moment). So most of your solar will be pushed back onto the electric grid.

With an ordinary meter, it is too stupid to run backwards, so it will run forwards. So generating solar will increase your electric bill!


To solve this problem, the power company must install a special meter, which has some added tech to be smart enough to "run backwards" and properly credit you for solar generation.

No, the bureaucracy in this country would keep me from ever connecting this.

Which means, they're not going to install the required "special meter".

That makes a "grid-tie" inverter completely pointless. For the money you spent on this thing, you could have bought the right stuff with batteries so it works at night. Research FIRST. Then buy.

Since grid-tie is pointless, the only thing worth thinking about is grid-down operation.

Which I gather is the central point of your efforts, since Philippine power is unreliable out in your district???

Well, that requires a completely different type of inverter. A grid-tie inverter is no use here.

All you need is a straightforward battery-and-inverter system.

Get yourself ~$1000 worth of batteries. On the solar side install a $100-200 Morningstar solar charge controller which charges the batteries. I like Morningstar because I like stuff that works, of course you can get cheap Chinese for 1/10 the price, assuming labor cost is no object lol. Then you need an inverter to run the fridge.

If you want, you can also add a grid-supplied battery charger, so that the AC power grid will keep the battery topped up when it is available.

Effectively the fridge would run off batteries 24x7, and the batteries would be refilled by solar and grid when available.

Straightforward stuff and at that same price point, with a respectable battery pack.

A typical modern refrigerator needs about 1000 watt-hours of power per day to run it, bump that by 50% to cover inverter losses and whatnot. Size batteries accordingly.

For the record: Phillipines is 240V-only. All of it.

I called SMA tech support and they said the inverter will not work on Single Phase 220v.

Actually, they're mistaken. Look at the manual, section 6.3.1 "Requirements for the AC connection". There is a table that lists four configurations. One of them is "240V delta", but they only use phases L1 and L2. That means it's a 2-wire, single-phase connection, and they don't know or care if it's 3-phase. It will work anywhere with ~240V across the 2 supply wires. I just described all of the Philippines. The whole country gets 2 supply wires with 240V across them.

Of course it's financial suicide if you don't get the power company to give you the special meter. And this is still the totally wrong inverter for you.

Many connections in Manila are 2 Phase 120v.

No. No, they're not.

All Philippine residential is 240V-only 2-wire supply. All. The difference is in Manila and other US-installed areas, they are wired like USA wiring but with the neutral wire deleted. This means the power is 240V-only, but it is center ground.

That means the voltage between a phase and ground is vaguely in the neighborhood of 120V. But this is not useful. If you try to attach 120V loads to it, it's going to slide all over the place - 130V, 95V, etc. because you have no neutral, so nothing keeps voltage at half.

The whole point of deleting USA-neutral is that the Philippines is harmonizing on the EU standard power distribution -- where power is distributed as 400V 3-phase power (230V from any phase to neutral). Any given house will get 1 phase and neutral, so it still is 230V. When a transformer fails, or when financing allows, they are going to replace that Yankee transformer up on the pole with a German one (possibly at 2 AM to get the power back on - they won't tell you). That won't affect anything that is ~230 volts.

Except. Some hillbillies want 120V, so right now they are tapping one phase wire, and bootlegging Yankee neutral off their ground wire. Once the German transformer goes in, they will be in for a rude surprise! All their 110V stuff will "go boom".

Unfortunately, weird hack-a-dack stuff like this is par for -- well, I hardly need to tell you how messy standards are there.

  • Are you sure I thought they had a 120 degree or 2 phase system not a true 180 like we have, the rest sounds plausible.
    – Ed Beal
    Mar 31, 2022 at 19:45
  • @EdBeal they have a mix. It was USA split-phase until independence in 1946, then probably for awhile after that. As they electrified new districts, they switched to Euro-spec 230/400V 3-phase "wye" with each house getting 1 phase and neutral. In the old disricts they give only L1 and L2, no neutral. So they only guarantee 2 service wires ~230V apart. Since both poles might be ungrounded, you must use 2-pole breakers for everything unless they say you don't have to (because you're in a Euro zone). Mar 31, 2022 at 21:45
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    @CoralGardener You're imagining the grid-tie inverter will make just enough electricity to stop your electricity meter, and no more. That is not possible. Grid-tie inverters are not capable of that. The SMA technician did not understand your issues because what you're trying to do is super weird. When you do weird stuff, you're on your own for support lol. Apr 1, 2022 at 1:43
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    @CoralGardener That makes sense, zero-export would require sensors on the power line, that's the only way it could know it's at zero. Your idea is "weird" because no one does it, because a) power buyback plans are readily available in its intended market, and b) your idea does not work. The energy needs of your house are very spiky, and do not line up with the "steady all day" output of the solar. Install an energy meter that shows your usage in 10-second intervals and look at the plot. It will be an eye-opener. You need a battery system. But it need not be thousands of dollars. Apr 2, 2022 at 5:54
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    @SimonB this is a Q&A site, not a "blanket statement that applies to all things" site. My advice pertains to OP, and you need to read comments to know what a mess this is. OP is in Philippines and does not have a meter like yours. Most plain old meters act as I describe. OP's inverter does not support a CT clamp, and OP is really fixated on that particular inverter, so your last 2 sentences, while true, are no help here. Apr 30, 2022 at 22:49

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