As the name suggest, self owned business model are the ones which require the consumer to invest themselves in the solar rooftop system. They can be further sub categorized as follows:

Gross metering:
Metering is an important aspect for financial settlement in the solar power plant. The number of units exported to and imported from the grid is recorded in the meter. Gross metering (from the two types of known metering arrangement models) uses two separate meters for recording the export and import of energy (Figure 2). While connected to the grid, the energy is fed into the grid at a tariff known as Feed in Tariff (FiT) and the consumer buys the energy at his normal applicable tariff. Prevalent in the areas with good grid reliability, this model would ensure a minimum (guaranteed) amount of return to the consumer.

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Figure 2: A typical gross metering arrangement (Source: Google images)

Net metering:
The second type of metering arrangement is known as net metering. Indirectly promoting captive consumption of energy, “net – metering uses the net difference between the export and import of energy measured by a bi-directional net meter (Figure 3). This type of arrangement does away with the need of storage as the energy (when needed say at night) is imported from the grid. Such model is suitable for few categories of consumer whose tariffs are higher then cost of generation from solar plant. Most utility/regulators tend to limit the size of the power plant such that the annual energy generation is less that the customer’s demand. Prevalent in the areas with good grid reliability, this model would generate revenue through potential savings for consumer and sale of excess energy to the utility (in few cases). An additional advantage to the utility is that the financial settlement is done at a tariff much lower than the FiT. From a customers view point, he would always consumer more than his generation capacity. This means that if he has his FiT lower than the utility tariff.

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Figure 3: A typical net metering arrangement (Source: Google images)

Let’s say a consumer’s consumption is 150 units (tariff of 10 Rs/kWh) and the generation is 100 units (with FiT of 6 Rs/kWh). By using gross metering one would pay the utility 900 Rs while by using net metering he would pay only 500 Rs. This means that a customer who is (almost always) consuming more than his generation, he would always tend to pay more in gross metering if his FiT is less than his tariff while compared to net metering where he would be paying for the net import of energy.

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Figure 4: Cost benefit analysis of gross and net metering

Captive consumption (off grid route):
Off grid captive consumption (Figure 5) kind of power plants are set up where the consumer has almost poor or no access to the grid. Such plants are set up with an intention to either consume or store all the energy generated by the plant. This plant can replace the old age Diesel Generator (DG) which could reduce both the cost and pollution however it would require a storage source (battery) to be integrated with it for continuous supply of energy. The only limitation of such system is that they (and the storage) are designed to supply energy only for particular number of days. Hence if there is no sun for a stretch, it may result in intermittent supply of energy.

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Figure 5: Flow of energy in captive consumption (Source: Google images