I have a building in The Philippines. Electricity there is 220 V dual phase for all the lights and outlets (wired like a US dryer but without the ground).
We are installing solar power and the contractor is installing 230 V single phase inverters (1 230 V hot and 1 ground on each unit).
We also have a 30KV 220 V dual phase generator installed. The utility drop and the generator will be separated from the solar by transfer switches (on just the 1 hot 230 line) but all of the 110 US appliances are wired to the individual 110 lines with a neutral and a ground like in the US.
He says it will be fine, I say it will blow everything hooked to it up and short out the utility feed and generator as well since he will be hooking one of their 110 V lines and 1 of the 110 generator lines to ground. I'm sure no one has experienced this but I would sure like an opinion from a professional.
Best Answer
If you have any 110/115/120V appliances, they can't work on unsplit 220/230/240V, period. In theory they could be ran in series, but the reality is that series work only as long as both loads are perfectly same. If the load varies (as it always do) the overloaded leg will get less than nominal and the underloaded will get more - and those appliances are at risk of blowing. The proper way of running those is to use a transformer to convert 220 into 2x110. Depending on how many 110V appliances you have, it could be cheaper to simply replace them with 220V ones and remove the last remains of 110V wiring.
For connecting 2X0V mains, generator and solar together, it's impossible to tell not knowing your exact wiring. You should consult a local electrician, because 1-pole transfer switch doesn't sound right without clear grounding. Understanding your grounding is the key here and as @Harper says, Philippines grounding is a non-trivial one.
As you're currently describing it, I'd say that solar should use 2x110V inverters with 2-pole switch. But, it's also possible that you already have the 220V/2x110V transformer on the mains line and your contractor simply plans to hook up there.
The situation could be far more dangerous than you're describing. If 220V with 1 leg grounded gets connected to 2x110V center ground, at first everything may seem like it's working, but the moment the mains or generator goes live too, 110V will appear between "solar ground" and "generator ground". Again, it could still appear superficially working, but a person touching the generator or a solar panel casing will get electrocuted with 110V. That's why I can only advise consulting an electrician that fully understands both the Philippines 110 to 220V conversion issues in general and the wiring of your building in particular.