solar kit

MicroInverters, Do-it-Yourself Solar Kits Anyone Can Install

by KURTIS on April 29, 2012

Since home solar became a commercial option some 40 years ago central inverters have ruled the industry. Today about 40 percent of the home solar kit market is made up of Microinverter kits. A inverter is an electronic device that converters the direct current produced by solar panels to alternating current which is the electricity you use to run your home appliances and lights.

A grid tied inverter or utility inverters converts the DC current from the solar panels into AC current then syncs the sine wave to replicate the wave form provided by your utility company. To the extent that the solar panels produce more electricity than the home requires, excess electricity is pushed backed by the inverter to the public utility grid where the utility grid purchases or credits the homeowner for the power produced.

Grid tied solar panel systems use the local utility company power as a storage bank drawing from the utility company when necessary and pushing power back to the grid when the demand from the home is low. In the past sizing inverters meant the homeowner interested in installing their own solar panel kit would usually have to enlist the services of a local solar company due to the complexity of the system and the opportunities for poor performance due to engineering issues.

Those design hazards are no longer such an issue thanks in part to the advent of microinverters which are now sold in most DIY solar panel kits. Microinverters are small electronic devices that connect to or under a single solar panel rather than to a group of panels. Solar installers like these inverters because their ability to turn the individual solar panel to AC electricity while minimizing issues such as shading. Microinverters are typically less than 250 watts and are more commonly 235 watts. The main reason is the limitations of the individual microinverters but that appears to be slowly changing. Home solar kits are usually sized according the average monthly usage of the homeowners. The size of the system you choose depends on the amount of power you require (Watts), and the available solar insolation in your area. Take your last 12 month utility bills kWh, for each month, total the 12 months worth then div by 365 days. Next look at the solar insolation level for your area (average sun hours) and divide your daily average by the average amount of sun. That total will give you the approximate size solar kit you need to offset your utility bill.

To increase the efficiency of inverters for solar panel kits the majority of grid tied inverters use a single maximum power point tracker. A MPPT means if you have a combination of solar panels that needs multiple orientations you will need an inverter system that can track the maximum power point of the different arrays facing different directions. What that means if you have say two strings of solar panels on a house facing two different directions or different angles. The power curve of the two strings are also going to be different because the two strings of solar panels are not receiving the same amount of sunlight.

If you use a central inverter that has only one MPPT, the inverter will not be able to lock into the best MPPT for the complete solar system. Microinverters have made huge strides to minimize that issue because each invididual solar panel has it own microinverters hence its own MPPT tracker. Microinverter systems are now an integrated platform for increasing the productivity and reliability of home solar kits. The combination of solar panels and a microinverter makes it much easier to maximize the solar harvest of the home kit. Home solar kits are now more efficient than ever with a high degree of safety. Solar design and installation has been made simple thanks to the new technology of microinverters.

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