PV Solar power

I have found companies that have interesting products related to PV solar power, while researching companies for positions.


Enphase - makes micro-inverters. All large PV arrays (larger than simple panels used to charge batteries or appliances) use inverters to convert DC to AC and tie it to the grid. Primarily many panels are connected in series to increase the voltage (and keep the current low to minizime losses) and connect to one large inverter to tie to the grid. The panels must be layed out carefully regarding orientation and the number of panels in each series . The drawback here is that a bad cell or panel , or a panel in the shade affects the power output of the whole array.

Micro-inverters are low power devices that are used , one per PV panel. Thus each panel outputs 120V (or maybe 240V) at a low current ( 1-2 A). The micro-inverter output of each panel are all effectively connected together in parallel, through one junction box to the grid.
The advantage is that each micro-inverter monitors its own panel and can turn it off if the output is marginal for any reason. The Enphase system enhances this by networking all of their inverters with power line networking. Their special router inside the house connects to the home internet. Enphase monitors the output of every inverter that is in use. Enphase can monitor units for failure as well as let the home owner view their power generation history. Additionally, panels can be mounted on various roof faces for installations that do not have a large south facing roof. For example a house could have a few panels facing south, east , and west if it did not have a single optimum mounting area. The panels that are shaded at any moment do not degrade the outputs of the sunny panels.
The one drawback is reduced reliability due to the increased number of inverters, but a single failure probably does not bring down the whole array. Also each inverter is a low power device and is monitored so any failure can be tracked.  This inverter is used in the Akeena PV panels (175 watts) sold at Lowes now, and it is what allows you to buy and install one panel at a time.

XET (XSLENT Energy Technologies) - also makes inverters. Their feature is power factor correction built into the inverter. Their inverters provide Impedance matching and power factor management. This allows their inverters to output reactive power (used by motors and switching power supplies used in most electronics now). They also make micro-inverters. They supply off grid inverters as well as battery charger PV controllers.

Smart Meters - smart grid - I just checked and the new smart meters can measure active and reactive power separately. Active power does the work, but reactive power is still provided by the power company and creates heat. Previously large industry was charged based on their power factor. I wonder if some of the higher power bills that are blamed on smart meters are due to PGE charging a penalty for reactive power ( like caused by air conditioning)?