Where do the DG Sets fit in:
For maintaining facilities in an apartment complex, some builders plan for a DG (Diesel Generator) set to provide electricity to essentials. Some essentials could be - Lifts in high rise buildings, Water pumps for Kitchen use and flushing, Fire-fighting systems, STPs (Sewage Treatment Plant) and so on. Most of these are high power devices (pumps / motors in the range of 2-10 HP). Lighting at apartment complexes too is not a small matter. Each individual lighting unit could be consuming a (relatively) small amount of power (10-50W). However, you will find that these units are 50-100 in numbers, which take the lighting power requried from 500W to 5,000W.
While common utilities need large power sources from the likes of a DG set, facilities inside the home can be better served by a home UPS. Home UPS come in ranges of 300 VA (for Desktop Computers) to 800 VA for nominal loads to 1200 VA for extended use. These are served by 120 AH or 150 AH batteries. The total cost of the setup (as of March 2021) range between INR 2000 to 4000 for Desktop Computer UPS and between 15,000 to 20,000 for the Home UPS for full home use. Square-wave inverters are about Rs. 1,500/- less than Sine-wave inverters.
If your society is planning to increase the number of output points from the DG Set, then these are points you might consider:
- Capacity of the DG set vs. expected peak load on the DG set: Most DG Sets are designed to run for long hours at 60-70% of peak loads. This could reduce slightly with age of the DG Set. When looking at peak loads, also consider one-time use equipments like Fire safety pumps.
- One-time setup costs: Verify the estimates from the Vendors for the following:
- One-time wiring and additional equipment costs (ACCL, additional switches, wires and their load bearing capacities)
- costs of any other consumables billed to you
- Labour costs
- Warranty in case of equipment failures
4. Cost of output power on DG: Power from a DG will be costiler than power from the Electricity Board. This is not even taking into account the sunk costs on the DG set. Get realistic figures to be safe.
UPS to the rescue
Individual UPS for houses could be a safe bet for the following reasons:
- Switching time: A UPS switches over instantaneously. Does not have the 30 - 45 seconds lag of a DG set.
- DG Availability: If BESCOM or your power Distribution Company is working just outside your area, you might have to shut down your DG Set for obvious safely reasons. At this point, your home UPS is your saviour. Same is the situation for DG maintenance or internal equipment maintenance.
- Overload on the system: In case of overload, individual UPS tripping does not impact the entire society.
- Individual Habits: When power is provided from DG sets to all the points, there are persons who tend to use it for their luxuries rather than use it for essentials. This ensures that the load guzzlers are subsidized by the prudent users.
- DG Set life: DG Sets tend to run longer on lower loads. As the load increases, the maintenance costs of the DG sets also increase.
- Impact on DG Set itself: If not properly planned, extension of existing DG set connections leads to failure of DG sets themselves. A DG Set could cost upward of Rs.12 lakhs at current prices with out GST.
- Future Use: If you end up using Individual Solar power at a
later stage, the solar power input will be connected to a battery. In
this case, you could reuse your UPS battery to be powered from the Solar
panel and used through the UPS. I have seen most Solar installations use
a UPS system either way.
- Future Costs: Government regulations keep changing for environmental and business reasons. What is allowed today may not be allowed in the next year. If the Government decides to impose a CESS on use of use of DG sets based on usage, you are forced to pay. If fuel prices go up, you incur the costs. (A good example of this is - In the initial days of Bangalore, you could dig a borewell in your land and enjoy the water - as free as sunlight. In the current Bengaluru, BWSSB charges you for the borewell use)
Overuse and Proper Use
Battery based UPS' too have their pitfalls.
- If you are not prudent about using your home UPS, the battery dies faster. In case of a power cut, it makes sense to switch off as many unwanted appliances as possible.
- Lead in most batteries is still an environmental hazard. Safe disposal practices are a must. When changing your battery, you can ask the seller to pick up the old one. They have a buyback price.
- Ensure that you check the battery for distilled water and refill with distilled water (only) when the level falls below the green points.
Use power and other resources judiciously. You will be happy and at peace.
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