Distributed INVERTER architecture makes solar more affordable, reliable and safe.

How inverter technology LOWERS solar and installation costs.

Inverter technology brings down solar costs

Advancement in inverter technology, distributed architecture, is expected to lower the cost of solar installation and maintenance, and with that, solar power will become main-stream in this country, but the speed at which this happens is largely reliant on the economics of the situation.

Installation Costs

The installation cost of a solar system depends on three things, 50% is the solar module, 40% is the balance of system (BOS), and 10% the inverter.

The price of solar modules has been lowered significantly, up to 50% in comparison to 2008. The commoditization of modules and the drop in prices makes the BOS, labor, and inverters even more crucial as they are now a bigger part of the cost of the installation.  This has led to an increase in interest for BOS and inverters. One cause for this increase in interest is recent advances in inverter technology, which affect everything from inverter costs to the costs of BOS and labor.

New inverter technology

The R&D of inverters focuses on two things, incremental advancements in the string/central inverter, and these advancements are largely aimed at improving efficiency and capacity. This has led to larger and further centralized inverters, like SMA’s 500kW 500U PV inverter.  The other focus has been on decentralizing architectures, like solutions such as DC to DC optimizers, which consists of added electronics which augment the central inverter, and total inverter solutions like a micro-inverter.

System Cost

The decreasing price of inverters and modules makes inverters a larger portion of the cost of installation. Inverter technologies can also significantly influence BOS and labor costs. For instance, a central inverter with a higher capacity can reduce the overall number of inverters needed in a large system and bringing down the cost of labor. This is, however, somewhat offset by the need for widely distributed DC wiring and expensive DC combiners and circuit overcurrent protection.

AC BOS equipment instead of DC junction boxes, connectors, and fuses are used in new AC-based inverter systems. Specialized DC BOS equipment is much more expensive than regular AC equipment, and can bring down installation costs. New inverter technologies like micro-inverters eliminate the need for a large centralized inverter, which brings down costs further. This holds especially true for a larger system, where a larger inverter can bring a whole range of requirements like a concrete pad, air-conditioned hut, fencing, and a crane to put the inverter in place.

New technology may also bring down operation cost of solar arrays. Micro-inverters ensure this array is less likely to degrade in performance due to dust or debris, and requires washing much less. Normal wear and tear of modules can bring down output by 5 or 6%.  Inverters with distributed architecture also allow you to delay maintenance.  In this type of system if one module or inverter malfunctions the outage is only limited to the module in question and the remainder of the array will function normally. Owners can plan for scheduled maintenance rather than wait for emergency maintenance.  Also, maintenance costs are lowered further because micro-inverters are easier to change and remove, and can be done by less skilled maintenance people compared to large central inverters.  Furthermore, the time needed to troubleshoot a PV array is significantly lower for systems with inverter communication and individual module monitoring.

Energy Harvest

Inverter technology greatly impacts the energy harvest of a system. The serialized design of modules results in something called the “Christmas light effect” in which any malfunction or impact on the performance of one module will affect others in the string. This is mitigated by distributed inverters because each module is independently powered. This also increases energy harvest. Sun-Edison recently designed and installed their first micro-inverter system, and its energy harvest was 20% higher than estimated during design.


All installers know about the problem of inverter reliability. The biggest issue is simply having to send a tech repeatedly to one place to troubleshoot a failure, and then go back to install a new inverter. Micro-inverters are more reliable for the unit and system. The reliability of the unit is much better most because of the distributed architecture where an individual unit converts only a small percentage of the array’s power. Micro-inverters often include a smaller thermal footprint and lower operating voltages, which bring down the stress on other components and increase overall reliability. For instance, the Enphase Micro-inverter 215WAC at 95.5% efficiency and its nominal operating voltage is 30-50V; higher system availability is due to the fact that even if one inverter fails it’s only a small percentage of the array. Furthermore, new inverter technologies come with per module monitoring, which allows the installer to quickly identify and swap out malfunctioning modules easily.


Improving PV safety means reducing the risk of fire and DC arc faults. There are two factors when it comes to PV fire safety, prevention and suppression. Fire risk can be reduced b AC-based inverter technologies because of an arc in the AC system will self-extinguish 120 times per second. AC systems also have no distribution of dangerous voltage and can be shut off before a fire needs to be fought, while also being safer for firefighters, whereas a DC system will stay on.
Enabling technologies

Micro-inverters certainly not new, there were models that were popular in the 1990’s, but these models were largely phased out due to the fact they couldn’t break the 90& efficiency barrier. The efficiency of new micro-inverters is easily comparable if not higher than more popular central inverters, and are more reliable as well. Many advances have made this possible, like ASIC technology that was important in reducing the size and reliability of the unit, compounds that allow the unit to withstand colder temperatures, and MOSFET’s with much lower resistance than 10 years ago. Also, new magnetic materials and electrolytic capacitors are perfectly suited for greater reliability and longer life spans when used in a low voltage micro-inverter.

Future Trends

Next for inverter technology is to integrate the inverter right into the PV module and make an AC module. This will be beneficial to consumers all along the solar value chain, and is favored by module manufacturers as a method of decommoditization for their offerings, which brings up revenue and profit. It eliminates a whole step in the process of installation and speeds up ordering and procurement, as well as the owners getting all the benefits of integration.
Distributed architecture is a significant step forward for all inverter technologies, and we can look forward to seeing more models in the future as micro-inverters create new market inroads. As these technological advancements continue the price point will surely keep declining until mass consumption is possible, if not inevitable.


The popularization of micro-inverters in the 1990’s failed to gain a foothold because of the limitations on efficiency, but with PC prices declining significantly greater attention is being given to BOS, labor, and inverters, which has led to resurgence in the field of distributed inverter technology.


Article written by Jennifer Coleman of Sun Source Solar Energy Brokers, providing solar brokering, brokerage, and solar energy consulting services in Santa Rosa, Marin, Sonoma, Napa, Solano and San Francisco Counties.  For more information, please visit

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