String inverter VS micro inverter

Generally the micro-inverter will always outperform string inverters, however when coupling string inverters with say a Tigo optimizer, your overall production should be the same if not higher. There is a great article comparing string vs. micro inverters. I use this sometimes to show the value of micro-inverters to clients, it is short and to the point. Personally for electrical and installations purposes I would always recommend a micro-inverter as the wiring done at the meter is less labor intensive and the cabling (generally trunk drop cabling) will be of better quality than PV 6 or 10. You will always produce more with micro-inverters because the sun rise and fall will harvest more, as well as low-light conditions. This amount may be neglected due to the higher upfront cost of the micro inverters.

The economics for micro inverters are moving upstream to larger commercial systems as well. I got a very aggressive micro inverter quote for a 603kW ballasted roof system in Rossville NJ The combined difference between wiring, combiners, DC breakers, installation time and everything between micros and a couple 250kw PV Powered inverters was @ 2 cents/watt. Over 20-25 years the granularity of monitoring and the ability to diagnose faults quickly over the web make the cost/value tradeoff a no-brainer. EPCs like micros because every time one or two blow out they get $150 per from Gozuk to roll a truck. Sooner or later their MTBF will climb to acceptable or even negligible levels and the price/cost advantage Also, do you know how many micro inverter watts you can put on an 18 wheel trailer compared to an SMA 500MV? You guys KNOW IN YOUR HEARTS the native AC module is the best shot we have of getting to the Sunshot goal of $1 per watt all in. So until the day they start making solar spray paint, I'm running my BOM and PVSyst production models with micros and centrals to get the client/investor the biggest possible ROI.

To date, I have never seen anything close to 2 cents per watt difference between micro inverters and string inverters. As to wiring cost - I have looked at this. A reasonably valid point, 2 wire versus 3 (since we can ground to our system). Diagnosing faults is potentially faster, a reduction in engineering and QA functions. The installation argument I do not understand. Installation of microinverters per panel is not less labor then combiner box and inverter wiring. Underground trenching, running of wires, etc are the same as far as I can see for our systems. We do not do roof mounting, but I also can not follow the difference here since conduit still needs to be laid out.

But matching of micro inverters is a cost overhead. Since panel efficiencies and size are constantly increasing, it is not uncommon to have to put a 460 watt micro inverter on a 300 watt panel. Thus inverter cost per watt has never been less than 63 cent USD more for micro inverters. In addition, low power clamping issues were a problem with Enphase (Circa, 1.5 years ago) and since our system is a pole mounted tracking system, shading is not a valid argument per se. We have not been able to determine real power output difference so far between string and micro inverters.

I do not see that replacement of an entire string inverter is realistic. Modular replacement is common, so UPS or FEDEX type shipments are reality. The 18 wheeler is only necessary for installing entire 500 kW to 2 MW. Go back to Solar inverter.