Series or parallel?
It might cost more for parallel wiring schema, but the results are quite better. Imagine a string of Christmas lights. Most are wired in series. When you pull out one light, they all go out. Now, if we put a dimmer in there instead of the light, the dimmer will lower the light of all the lights in the string. The same thing applies to solar panels wired in series. If one panel is shaded, they will all act as if they are shaded, even if they are in direct sunlight. If you have panels aimed at different angles to the Sun on various parts of your roof, you will always only generate power matching the least illuminated panel. In those cases, you may need more than one string inverter.
String inverter: series wiring
String inverters have been around a long time. They have a lifespan of about 10 to 12 years before needing to be replaced. They are the lowest cost inverter to be used. Beware of sales tactics here. Your initial cost may be lower, but you may be buying and installing string inverters every 10 years or so at a cost of between $2000 to $4000 each. That can eat up a lot of solar energy profits. For a small investment, you can do a lot better.
Power Optimizer: series wiring with a twist
In this configuration, you have a special type of micro-controller under each panel which works in conjunction with an inverter located near your power panel. The purpose of this relationship is to harvest more power in shady vs. sunny locations on the roof. Rather than having a separate inverter for each array location which faces a different azimuth, one power optimizer can help overcome this problem. There are more "parts" than the simple string inverter setup, but there is an improvement in power harvest. In this situation, you still have the problem of series wiring limitations. This setup typically costs more than the series string inverter mentioned above, but less than the micro-inverters. Power harvest can exceed that of micro-inverters. The stress on the main inverter is reduced, giving it a longer lifespan. Inverters (with or without power optimizers) have string limitations that are not a problem for micro-inverters.
Micro-inverter: parallel wiring
Last is the micro-inverter. In this setup, you have a micro-inverter under each panel. This allows for more energy harvest than a string inverter but less than a power optimizer, individual panel monitoring, and long-term reliability. Now, if shade obscures one panel, no other panels are affected, like with power optimizers. The manufacturer states that this allows for 5% - 25% more power harvest than a standard string inverter.. In my experience, few if any of the micro-inverters need replacement. Warranties are generally 20 or 25 years for micro-inverters and power optimizer systems. Power optimizers are commonly used with leases today. (Micro-inverter setup shown below, similar to power optimizer but without central inverter).
You also will have a monitoring system available,m with power optimizers or micro-inverters, on your computer or your smartphone at no additional cost as shown in the next video. Your panels are monitored by a third party for 20 - 25 years, every hour. In the very unlikely event anything should fail, instant information is sent to the monitoring agency at no cost to you, and replacement parts are sent and installed, also at no cost to you, under warranty. Power optimizers and micro-inverters have monitoring programs, which are very similar to the Enphase monitoring video shown next.
When comparing the benefits of micro-inverters and power optimizers (next video), it is also important to take into account the expected life of the central inverter used with power optimizers. You may have to replace the central inverter every 10-12 years at a considerable cost ($2000 - $4000 each), thereby negating some of your benefits of having solar.