Transformerless inverters

Do I need a step up transformer for a residential installation or will a TL inverter do?

I think you’d be hard pressed to find a residential inverter with a transformer these days. What brands are you comparing?

@blauvelt

All modern solar inverters use a transformerless design due to the low cost and high efficiency. The inverters operate with a wide PV input voltage range usually from 100V up to 600V DC.

Transformers are only really used these days in the more powerful off-grid battery inverter/chargers which need to power appliances with high surge loads.