OK, here is my opinion. Anyone who believes that you would be wasting a lot of power does not know what they are talking about. First - panel wattage is determined in a lab under perfect conditions - something rarely (if ever) seen in the real world. In fact, California has a different rating system for panels that, to some degree, takes into consideration basic real world conditions.
Peak production from panels is reduced by many factors including:
Use of string inverter - string inverters are inherently less productive than micro-inverters. String inverters deal with power from multiple panels as one unit. Micro-inverters (at least from Enphase) deal with each panel individually. Therefore a negative effect on one panel will not impact any other panels.
Length of cable run - The longer the cable run from the panel to the inverter and from the inverter to the home electrical panel the greater the loss of power.
Shading issues - Even with power optimizers, my experience and the studies done, show that Enphase still out performs string inverters for overall power production.
Dirt, dust on panels - reduces the power production of all panels regardless of the inverter used.
Angle of panels to the sun - if the panels are not correctly angled to the sun, they will not reach peak performance. This angle actually changes in two ways: 1 - as the sun rises and sets, for most of the day the panels are not correctly angled and the sun is striking the panel at an angle that changes as the sun moves from East to West. This means that for most of the day there is no possibility that the panel can reach peak performance. 2 - as the year progresses the sun is higher or lower on the horizon. So, fixed position panels will almost never be at the perfect angle to the sun for peak production. For example, where I am in Mexico the yearly variance of sun angle is 40 degrees between summer and winter. To get the peak performance from the panels, we would need to adjust them almost weekly by 1 degree.
Heat - while possibly not as great an issue where you are, heat has a detrimental effect on the power production for all panels. Panels are tested at 25 degrees Celsius and, for every degree of temperature rise there is a corresponding drop in panel performance.
Hours of maximum potential production - The core hours for maximum performance is actually a very small percentage of the total day. For most of the day, for the reasons noted above, the panels are not even close to their peak wattage rating.
Finnaly - Enphase has undertaken production studies and comparisons from around the world in many different locations and under all kinds of different conditions and in every instance they have outperformed string inverters (even when equipped with optimizers). As well there have been at least two independent studies that I am aware of that have produced the same or similar results. I have yet to see any studies done by any string inverter manufacturer that says their product out performs Enphase for total power production.
Our real world experience bears this out. We have installed string inverters and string inverters with optimizers and in every case Enphase micro-inverters outperform the string inverters.