Power Grid Types (On Off Grid / Grid Types / SPI inverters)
Power Grid Invereters
Off-Grid and Grid type inverters generate power for general use like any AC power. SPI generates power specifically for pumps to optimize power use and to control pump speed at the same time. It is an industrial solar inverter dedicated to power and control pumps more efficiently than conventional off-grid or grid type inverters.
Industrial pumps are currently powered and controlled using VFD (Variable frequency Drive) that are fed by three phase AC current to operate pumps in various speed. Off-grid and grid type inverters would require extra investment to add VFD to operate pumps. SPI already embeds solar VFD (S-VFD) that can be fed directly from Solar PVs to operate three phase pumps using solar power only (solar mode). It also can be fed, at the same time, from PVs and AC source (like diesel Generators or Utility grid) to operate in hybrid mode. It always gives solar power source higher priority as the main power and uses only portion of AC power source when solar radiation is low ( like cloudy weather), or to operate pumps at night time. SPI is about 30% more power efficient to operate pumps than conventional solar inverters (means require 30% less PVs).
Solaropia SPI Advantage
In Addition to power optimization, SPI demonstrates extra advantage over the two types of inverters:
Compared to off-grid inverters, SPI has two main great advantages. It does not require batteries to invert PV power, as off-grid inverters require it. Batteries are very expensive – they need extra PVs and increases the off-grid solar system cost by 50%-70% (batteries also depreciates over 2-3 years while PVs in 15 years, and suffers from leakage and demands good maintenance especially under high temperature conditions). Another important advantage is SPI offers units up to 500 KW inverters while off-grid are limited to less than 10 KW. To generate higher power (maximum 100 KW) multiple inverters will be arranged in array which causes synchronization problems and makes off-grid systems instable. SPI solves high power application reliably and at considerable lower cost.
Compared to grid type inverters, SPI can operate pumps when grid power is not always available or turning On-Off for any reason. SPI is grid independent while grid inverters require grid-power always on to generate power. Even when diesel generators (DG) are used to emulate grid – it has to be always ON at least at 45% power load which consumes expensive fuel, pollution and noise of DG. SPI uses DG only in emergency cases. Additionally, Grid inverters will require VFD as extra system to operate pumps while SPI offers it as one system.