Due to lot of push from the Government, media attention and efforts by the project sellers, the Pure-Grid-Export Solar Inverters are becoming popular.
It indeed looks a simple, cost effective and hassle free solution. Here are some interesting aspects.
A typical Grid-Tie Inverter works as shown above.
As the Sun starts shining, the PV Panel starts generating DC Power, which is then converted into usable AC and is supplied to the internal AC loads connected (like lighting, Fan, Fridge, TV, Air-condition, Motors, any appliance/equipment ) and
if the internal load is lesser than the power generated through such PV + Inverter Combination, the energy goes to Grid for which if the Meter is replaced with new generation NET-METER, the Energy is then EXPORTED to Grid in this period which would be recorded and accounted for in the monthly billing.
Fig 1(b) gives an idea about the pattern of the power generated on daily basis with peak occurring between 10 AM till 2.30 PM on a normal clear day but duration can vary from place to place.
The salient features are:
- Converts PV Solar Energy into usable AC Energy in most efficient manner.
- Works only when Grid power is available in day time.
- As a thumb rule it generates approx. 4.5 DC units per day which means approx 3.7 AC usable unit per.
- It works with DG under certain restrictions only.
All above looks fine till consider few more interesting aspects. Some of them are:
- In any area, the local Electricity supply company called DISCOM has the responsibility to install distribution Transformer and have restriction of maximum 10% extra power on same infrastructure. So they may accept application to install such solar plant on First-cum-first basis.
- All DISCOMS buy Electricity @ Rs. 3.5 to 4.5 per unit and sell between Rs. 5.30 to Rs 10.00 per unit taking into account their administrative expenses and have PPA where they have to pay as per agreement whether it is consumed or not .
- To offset it, DISCOMS also offer different rates of Electricity to all non-residential users termed usage on Time of Day (TOD).
- So what will be incentive to DISCOM to buy Electricity @ such high rate and reduce their revenue both with buyer and seller with every roof generating at same time?
- In absence of any long term PPA between consumer and DISCOM, how long this alliance will work at such high rates of purchase?
So make a Intelligent Investment to your Green Energy Commitment.