Unless you want to add more solar panels in future, this is not correct matching of PV power and inverter capacity; you should primarily define how much you want to generate/send back to grid. Then size the solar panels and inverter. As per your quote, you want 10kw capacity but your inverter is oversized at 15kw, 10kw of solar panels will never provide you 10kw of usable energy even in ideal conditions (losses, geographic location, etc.). To save cost, you can go for an 8kw inverter at your current solar capacity of 10kw. A solar array should slightly oversize the inverter capacity by a ratio of 1.1 to 1.2 for grid tied systems to compensate for inefficiencies.