The inclusion of distributed energy resources (DER) on the LV network has implications as to the integrity of the quality of supply.  This is manifest in many areas.  Voltage control – switching of DER may cause rapid variation of voltages on the network.  MV/LV transformers may have off load tap changers or limited OLTC capability.  Distribution network operators (DNO) may implement wider ranging tap changers as well as OLTC on MV/LV transformers.  Fault level – DER may increase fault level to unacceptable levels.  High impedance transformers or limiting DER fault level contribution may be options for mitigation.  Harmonics – DER may distort the waveform.  Analysis on the extent is necessary to determine the limit of DER.  Thermal limits – Some utilities limit MV/LV transformer loading to 50%-65%.  This may limit the amount of DER permitted on the feeders.  Reverse power flow – this can affect certain tap changes as well as protection settings.  Replacement of relays and modification of tap changes may be necessary.  The strategies and practices of utilities to deal with these issues is covered in this brochure.  Understanding of this is essential for deciding on the best practice for your utility.