A solar inverter converts the variable direct current (DC) output of a photovoltaic (PV) solar panel into a utility frequency alternating current (AC) that can be fed into a commercial electrical grid or used by a local, off-grid electrical network. It allows to the use of ordinary AC-powered equipment with solar power.
Solar inverters may be classified into three broad types: Stand-alone inverters that do not interface in any way with the utility grid, Grid-tie inverters which match phase with a utility-supplied sine wave ( shut down automatically upon loss of utility supply) and Battery backup inverters (capable of supplying AC energy to selected loads during a utility outage) . Solar inverters have special functions adapted for use with photovoltaic arrays, including maximum power point tracking (get the maximum possible power from the PV array) and anti-islanding protection (for backup inverters). Solar grid-tie inverters are designed to quickly disconnect from the grid if the utility grid goes down. Wikipedia solar inverter page amd Texas Instruments Solar Inverters web page provides some technical introduction to solar inverters.
Solar panels power grid connected inverters is pretty new technology just boosting to become widely used. It seems that the manufacturers and sales companies have still things to learn. Solar panels power grid connected inverters, ie the operation of inverters found in Finnish Safety and Chemicals Agency (Tukes) and the 13 other EU market surveillance authority joint campaign plenty of flaws. Market surveillance authorities inspected during the campaign a total of 55 solar panel systems to be connected to the mains inverter. Almost all (91%) were non-compliant: They sent the environment too much electromagnetic interference or labeling of the product, the information and documents were incomplete. The majority of the products checked had been manufactured by an EU or EFTA area.
For more details read EMC Market Surveillance Campaign 2014 REPORT: SOLAR PANEL INVERTERS. The primary purpose of the campaign was to assess the compliance of samples taken from the market with the provisions of the EMC Directive. Administrative compliance was checked against the CE marking and Declaration of Conformity. General marking requirements, user information and Technical documentation were assessed on an optional basis. In general, the level of compliance with the administrative and technical requirements was considered very low: Overall, only 5 (9%) of the Equipment Under Test (‘EUT’) were assessed as compliant.
In general this means that you need to be pretty careful when you are buying alternative energy equipment!
The report recommends that the results of the campaign should be publicised widely throughout Europe and the other countries where the products originate. Publicity should target all economic operators in the area of solar panel industry. I will agree on that, and that’s why I brought this topic up in the blog.