sizing a grid-tied inverter for a PV system

soukaelber

i had a question please, i am working on a project about sizing PV system grid-tied , in my project i have to design the system the way that the inverter should shutdown the PV modules when there is a excess of electricity , because in our country it s not allowed to sell the surplus to the grid. at the same time, in bad conditions of the PV system, we need to take electricity from the grid. HELP. plz!

mcgivor

There are ways to achieve what it is you require, the use of suitable equipment is the key to how it can be achieved. One example is to use a system which allows grid supported AC coupling, this allows the PV to support loads during the day whilst allowing the grid to take over when the PV is no longer available. Such equipment is programmable to not inject into the grid but able to use grid when required, the size of the array would be dependent on loads, no point in over production when the opportunity to sell dose not exist. Sizing the array would be critical, an inventory of day time loads would be the first step, this can be done with logging equipment 

Some questions, dose the grid utility allow grid tied but will not pay back if injected? Or do they not allow injection?
Regarding the grid, is it stable? or are there frequent outage?, battery backup can be useful if this is the case.
Do you have peak billing, when the price is higher during certain hours, or is it a flat rate 24 hours, again batteries could be used to offset peak billing.

Just some ideas/ thoughts to get the ball rolling, so to speak, attached is a file which may shed some light, and Welcome To The Forum