Planning new PV plant

Re: Planing new PV plant

SMA is probably the best quality manufacturer of GT inverters at this time (and their hybrid/off grid models too).

I have not heard of any specific problems with SMA GT inverters not starting unless the Grid Power is not stable (voltage too high/too low, line frequency more than +/- 1% of nominal, etc.).

Otherwise, pure Grid Tied inverters (solar panels + GT inverter) will only operate when the utility power is present. If utility power is down, GT inverters will shut down too (no emergency backup power).

If you want backup power, you need to install a different inverter system + battery bank. Much more expensive. There are "pure" off grid inverters (solar panels, charge controllers, battery bank, off grid inverter) and there are "hybrid" inverter systems--Similar to off grid systems except that a hybrid inverter can behave like a GT inverter when the utility is running (sell excess power back to the utility) and run in off-grid mode when the utility power is off (like a computer UPS system).

Does your country/utility support "net metering" or some other method of billing for Grid Tied power? In many countries, grid tied solar power systems are not legal and you cannot sell power to the grid (turn the utility meter). In the US, many new electronic utility meters will report running backwards or even charge the user extra money if they "illegally" sell power back to the grid).

-Bill

Re: Planing new PV plant

I am typing about the public utility grid voltage/frequency.

There has been a few issues with utility voltage near the maximum allowed (around 264 VAC in the US), and somebody has a long circuit run from the GT inverter to the utility connection. The high line plus the voltage "rise" of the GT inverter AC circuit is high enough the cause the GT inverter to "fault".

In a few cases I have read here, the installer was able to reprogram the GT inverter a few volts higher and stop the faulting. In other cases, the utilities were asked to change the tap on the transformer and bring the line voltage down a bit to a better nominal value.

Here in the US, ~10 kW is usually the maximum system size for a "residential" Grid Tied Solar Install.

A 100-200 kW system is not small, and here would require a utility engineer to review the interconnect and feed to the utility grid. In some cases, utilities have refused to allow larger systems to interconnect as it would cause problems with the utility (too much energy from local GT installations overloading the local grid--as an example--Some places in Canada were known for granting permits then refusing connections after the systems were actually built).

Whether or not you can install the system yourself, you will need to involve your local electrical inspectors, utility, and possibly employ a licensed electrical engineer to design your system.

You might contact your local SMA representative and see what advise they can offer. Your system is fairly large and their engineering/sales support may be needed anyway.

-Bill