Unless you know the open circuit amps and voltages that you will be working with buying and installing an inverter now would be a waste of time. The inverter will be size according to the solar array that is installed.
Planning on going off grid and depending on photovoltaic panels as your sole source of power will be expensive to say the least. In North America there is only 4 hours average of sun a day which means you will need a battery bank to back up the photovoltaic array on those days where the sun can’t do the job.
Should you decide to go without entertainment such as TV and video games and using all gas appliances including refrigeration you might get by for around $50,000 up front money. If you are planning on big screen TV, surround sound, DVD players, electric refrigerators and the such then double you startup cost.
Last I heard just for the panels and their installation is going for ~ $10 per watt. If I was planning on going off grid I would plan on everything I used to be DC and no inverter.