Off-Grid Solar Systems in Chennai
Off-grid solar runs a property entirely on panels and batteries with no grid connection at all. It is the right answer for farmhouses, remote plots, agricultural land and sites where a connection is impractical.
Said before the survey, not after
It is usually the wrong answer for a house in Chennai that already has working TANGEDCO supply — and we will tell you that before we survey rather than after.
Honest qualification first
Proper load audit and autonomy sizing
One year free maintenance
Installing in Chennai since 2020
The fundamental difference
Surplus in an off-grid system is wasted, not credited. There is no grid to export to, which is why off-grid sizing is a balancing act rather than a maximisation.
Qualification
Is off-grid solar right for your site?
Off-grid solar is designed for locations without a usable grid connection. It genuinely suits farmhouses, agricultural land, remote plots, construction sites, borewell pumping and properties where obtaining a TANGEDCO connection is impractical or prohibitively expensive. For a property that already has a reliable connection, off-grid costs substantially more, receives no PM Surya Ghar subsidy and earns no net metering credit, in exchange for independence the property was not lacking.
Off-grid is genuinely the right choice if
- There is no grid connection at the site, and obtaining one is impractical or costly
- The property is remote — agricultural land, a plot outside the network, or a farmhouse well beyond the last pole
- The application is a borewell or irrigation pump on land without supply
- It is a temporary installation, such as a construction site or a site office
- The supply is so unreliable that it is effectively absent — rare in urban Chennai but it occurs in some outlying areas
- The load is small and defined, such as lighting, pumping and a few appliances rather than a full household
Off-grid is the wrong choice if
- You have a working TANGEDCO connection, however much you dislike the bill
- You mainly want backup during power cuts. That is what hybrid systems with battery backup are for, and they cost far less
- You want the ₹78,000 subsidy, which requires a grid-connected system
- You want the shortest payback
If you have a connection and want backup, read on-grid vs off-grid vs hybrid instead, or look at on-grid solar systems.
Our position, stated plainly. We install off-grid systems where they fit. We will also tell you when they do not, because an oversized off-grid system on a property with a working connection is a poor investment that we would rather not be responsible for.
Components
What an off-grid system is made of
An off-grid solar system comprises panels, a charge controller, a battery bank, an off-grid or standalone inverter, and the protection and distribution equipment around them. The charge controller and the battery bank are the two components that do not exist in a grid-connected system, and they are where off-grid design succeeds or fails.
| Component | What it does | What matters |
|---|---|---|
| Solar panels | Generate DC power | Sized for the worst month, not the average |
| Charge controller | Regulates charging of the battery bank from the array | MPPT rather than PWM on all but the smallest systems |
| Battery bank | Stores energy for night and cloudy periods | Chemistry, usable capacity, depth of discharge, temperature |
| Off-grid inverter | Converts DC to AC for your appliances | Continuous rating and, critically, surge rating for motor loads |
| Protection and distribution | Isolation, breakers, surge protection, earthing | Often thinned in cheap quotes |
| Generator input, optional | Charges the bank during extended cloudy periods | Worth considering — see the generator section below |
MPPT or PWM charge controller
A PWM controller is simpler and cheaper. An MPPT controller extracts meaningfully more energy from the same array, particularly in low light and cooler conditions, and allows more flexible array configuration. On anything beyond a very small system, MPPT is worth the difference, because the array is the expensive part and you want all of it.
How power flows
Panels charge the battery bank through the controller. The inverter draws from the bank and supplies your appliances, day and night. When generation exceeds what you use and the bank is full, the surplus is simply not harvested, because there is no grid to export it to. Surplus in an off-grid system is wasted, not credited.
The engineering
Why off-grid systems are sized completely differently
An off-grid system is sized for the worst conditions rather than the average, because there is no grid to cover a shortfall. The design has to satisfy the load through the least productive period of the year, typically consecutive overcast days during the northeast monsoon, which means both a larger array and a substantially larger battery bank than a grid-connected system serving the same property.
The four inputs that determine the design
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Why this makes off-grid expensive
All four factors push the same way: bigger array, bigger bank. An off-grid system serving the same daily load as a grid-connected one is typically substantially larger, and the battery bank is a major share of the cost.
The question to ask any off-grid installer
What days of autonomy have you designed to, what depth of discharge have you assumed, and which month did you size against?
An installer who cannot answer all three has not designed the system. They have quoted a package.
The battery bank
Battery selection and what it means over time
The battery bank is the largest single cost in an off-grid system and the component that determines both its performance and its running cost, because it will need replacing during the system's life while the panels will not. Chemistry, usable capacity and operating temperature all affect how long it lasts.
| Battery type | Characteristics |
|---|---|
| Lead acid, including tubular | Lowest upfront cost, shortest service life, shallower usable depth of discharge, requires ventilation and periodic maintenance |
| Lithium, including LFP | Higher upfront cost, considerably longer service life, deeper usable discharge, lower maintenance, usually better value across the system's life |
What to establish before buying
- Usable capacity, not nameplate. Ask what the design assumes for depth of discharge.
- Warranty terms in writing, including whether stated in years, in charge cycles, or both. Cycle-rated warranties are the more meaningful measure.
- Replacement cost and timing. Off-grid running cost is dominated by battery replacement. Budget for it from the outset.
Chennai heat shortens battery life
Batteries degrade faster at high ambient temperature, and Chennai is hot for most of the year. Where the bank is installed matters: a ventilated, shaded, reasonably cool location will materially outlast a bank in an unventilated enclosure on a west-facing wall. This is a design decision that costs nothing to get right and a great deal to get wrong.
Do not oversize the bank casually
A larger bank costs more upfront and more at every replacement, and if it is rarely cycled deeply it delivers little for that cost. Autonomy is worth paying for up to the point where it matches how the site is actually used, and not beyond it.
The load audit
Why off-grid design starts with a list of appliances
Off-grid design begins with a complete inventory of every load: each appliance, its power draw, and its daily running hours. Unlike a grid-connected system, which can be sized from twelve months of electricity bills, an off-grid site often has no bills at all, and the system must be designed against what will actually be run rather than against an estimate.
Every appliance
with wattage and daily run hours
Seasonal variation
since fan and pump usage changes considerably through the year
Which loads are essential
And which could be dropped during an extended cloudy spell
Surge loads
the most common cause of off-grid systems failing in service
Surge loads, and why they catch people out
Motors draw far more current starting than running. Borewell pumps, water pumps, compressors, refrigerators and air conditioners all surge on start-up, sometimes to several times their running draw. An inverter sized only to the continuous load will trip when the pump starts.
This matters more on off-grid than anywhere else, because there is no grid to absorb the surge. The inverter's surge rating, not just its continuous rating, has to accommodate the largest motor on site starting, ideally with something else already running.
Tell your installer about every motor, particularly borewell pumps, and be specific about horsepower. A pump omitted from the load list is the single most common reason an off-grid system fails to do what its owner expected.
Off-grid asks for load discipline
A grid-connected property can add an air conditioner without consulting anyone. An off-grid property cannot, because the system was designed against a specific load list. Adding significant load later means expanding the array, the bank, or both. This is worth understanding before installation rather than discovering afterwards.
Generator backup
Should an off-grid system include a generator?
Many off-grid installations include a generator input, allowing the battery bank to be charged from a DG set during extended cloudy periods when solar alone cannot keep up. Including this option often allows a smaller, cheaper battery bank than designing for full autonomy through the worst possible monsoon spell, since the generator covers the rare extremes instead of the batteries carrying them.
Designing for full autonomy
Means a very large bank sized for the worst case, which is expensive and mostly idle.
Designing for typical conditions with generator backup
Means a smaller bank and occasional fuel cost during exceptional periods.
For farmhouses and agricultural sites that already have a generator, adding the charging input is usually the sensible economic choice. For sites where running a generator is impractical, autonomy must carry the load and the bank sizing must reflect it.
This should be a deliberate decision at design stage, with the cost of each approach set out, not a default assumption either way.
Subsidy
Is there any subsidy for off-grid solar?
Off-grid solar systems are not eligible for the PM Surya Ghar Muft Bijli Yojana, which is a subsidy for grid-connected residential rooftop systems with net metering. This is a significant part of why off-grid is more expensive overall, and it is a decisive argument against choosing off-grid at any property that has a usable grid connection.
One route that may apply: PM-KUSUM for agricultural pumping
Farmers and agricultural landholders installing solar pumps may be eligible under the PM-KUSUM scheme, which supports standalone solar pumps and the solarisation of existing pumps. It is a separate scheme with its own eligibility, application process and domestic content requirements, and the terms are revised periodically.
If your off-grid requirement is agricultural pumping rather than a household supply, this is worth investigating before you buy anything. Check the current scheme terms and eligibility through the relevant state and central channels, since conditions change and eligibility depends on landholding, pump capacity and the specific component of the scheme.
For everything else off-grid: there is no subsidy, and any quotation implying one should be questioned.
The grid-connected routes and their ₹78,000 entitlement are covered on the PM Surya Ghar subsidy page.
Running cost
Ongoing cost and maintenance
An off-grid system's running cost is dominated by battery replacement, which will occur at least once and often more than once during the twenty-five year life of the panels. Beyond that, maintenance covers panel cleaning, battery inspection and terminal maintenance where the chemistry requires it, charge controller and inverter checks, and monitoring of system performance.
Battery bank
The main recurring cost. Inspection, terminal cleaning and eventual replacement.
Panels
Cleaning, more frequently in dusty or agricultural settings.
Charge controller and inverter
Periodic checks, and eventual replacement of the inverter.
Wiring and protection
Annual inspection, particularly on exposed rural installations.
Ventilation
Where lead acid batteries are used, ventilation must remain effective.
Remote sites need more thought about service access
A system on agricultural land an hour outside the city is harder to attend than a rooftop in Adyar. Agree what the maintenance arrangement actually looks like before installation, including response times and whether visits are scheduled or on call.
Every Blues Renewables installation includes one year of maintenance, with an AMC available afterwards.
Mistakes
Five ways off-grid systems disappoint their owners
| # | The mistake, and what it costs |
|---|---|
| 1 | Choosing off-grid when a connection exists. More cost, no subsidy, no export credit, a battery to replace. This is the largest and most expensive mistake. |
| 2 | Omitting a pump from the load list. The system works until the borewell starts, then trips. Surge loads must be in the design. |
| 3 | Sizing against the annual average rather than the worst month. The system performs well for nine months and disappoints for three, every year. |
| 4 | Buying on nameplate battery capacity. Usable capacity is a fraction of it, depending on chemistry and depth of discharge. A bank sized on the wrong number underdelivers from day one. |
| 5 | Adding load after installation. The design was built against a specific list. New air conditioning or a second pump means expanding the array, the bank or both. |
Free, no obligation
Find out whether you need off-grid at all
Start with a conversation rather than a quotation. Tell us where the site is, whether there is a grid connection or any prospect of one, and what you need to run. If off-grid is genuinely the right answer, we will carry out a load audit and design against it properly. If it is not, we will say so and point you to the option that fits.
What the assessment covers
- Whether a grid connection exists or could reasonably be obtained
- A full load audit, including every motor and its surge requirement
- Days of autonomy and depth of discharge, decided with you rather than assumed
- Design against the weakest month, not the annual average
- Whether generator backup would reduce the overall cost
- An itemised quotation naming every component
Common questions
Off-grid solar, common questions
A solar installation that runs a property entirely on panels and battery storage with no grid connection at all. Panels charge a battery bank through a charge controller, and an off-grid inverter supplies your appliances day and night. Since there is no grid, surplus generation is not exported or credited, it is simply not harvested.
Rarely, for a property with a working TANGEDCO connection. It costs substantially more, receives no PM Surya Ghar subsidy, earns no net metering credit and requires a battery bank that will need replacing. Off-grid genuinely suits farmhouses, agricultural land, remote plots, construction sites and locations where a connection is impractical.
No. The PM Surya Ghar subsidy applies to grid-connected residential rooftop systems with net metering, so off-grid installations are not eligible. Agricultural solar pumping may be eligible under the separate PM-KUSUM scheme, which has its own terms and eligibility conditions and should be checked directly.
Against the worst conditions rather than the average, because there is no grid to cover shortfalls. Design starts with a full load audit listing every appliance and its running hours, then sets days of autonomy, applies a realistic depth of discharge to determine usable battery capacity, and sizes the array against the weakest month of the year rather than the annual average.
The number of consecutive days the system must run without meaningful sun, carried entirely by the battery bank. More autonomy means a larger and more expensive bank. It is a deliberate cost decision and should be made by the owner rather than assumed by the installer.
Because it must satisfy the load through the least productive period of the year with no grid to fall back on. That means enough battery capacity to carry consecutive overcast days and enough panel capacity to recharge the bank afterwards, which is substantially more of both than a grid-connected system serving the same property.
Yes, provided the inverter is sized for the pump's surge current and not just its running load. Motors draw far more starting than running, and an inverter sized only to continuous load will trip when the pump starts. Tell your installer the pump's horsepower explicitly, since an omitted motor is the most common cause of an off-grid system failing to do what its owner expected.
A PWM controller is simpler and cheaper. An MPPT controller extracts meaningfully more energy from the same array, particularly in low light, and allows more flexible array configuration. On anything beyond a very small system, MPPT is worth the difference because the array is the expensive part.
Considerably less than the panels, which are warranted around 25 years. Lead acid types have a shorter service life and require ventilation and periodic maintenance, while lithium types such as LFP last substantially longer at a higher upfront cost. Chennai's heat shortens battery life, so a ventilated, shaded installation location matters.
Only within the design's headroom. The system was sized against a specific load list, so adding significant new load such as air conditioning or a second pump usually means expanding the array, the battery bank or both. Off-grid asks for more load discipline than a grid-connected property does.