Your building's roof can pay your electricity bill.
We put solar on the one roof you all share. Our patented SPDU then divides that power fairly between every flat, shop and office under it. Families in our first building get 100 free units of electricity every month.
- 300 flats powered
- 3 patents
- IGBC Platinum pilot
- Harvard Business Publishing case study
100 free units
per flat, every month
Lower bills
from day one
Your society has solar. So why is your bill unchanged?
Because until now, shared rooftop solar could not reach individual homes. That is the exact problem Protostar was founded to solve.
One roof, many homes
In a building with 24 flats, there is only one roof. Until now there was no way to give each home its own share of the solar power it makes. So flats were simply left out.
Solar that only lights the staircase
Most societies that install solar use it for common areas: the lift, the lobby, the water pump. Useful, but it barely dents what each family actually pays every month.
Your bill stays exactly the same
The panels are on your roof. The sunshine is free. And yet every flat keeps paying the full electricity tariff, year after year, as if the solar was never installed.
Three steps. Zero changes inside your home.
Think of your rooftop like the society's water tank. Everyone shares one supply, and every home gets its fair, metered share.
Step 01
Panels go on the shared roof
We cover your rooftop with solar panels on a raised structure. The space below stays usable, the roof stays cooler, and the waterproofing lasts longer.
Step 02
The SPDU divides the power fairly
Our patented device sits in the meter room and gives every flat, shop and office its own metered share of the solar power. No wiring changes inside your home.
Step 03
Your meter runs on sunshine first
Each unit uses its solar share before drawing from the grid. At night or in heavy monsoon, the grid takes over automatically. You never notice the switch. Your bill just shrinks.
The SPDU (Smart Power Distribution Unit)
Fits in your existing meter room. Installed in weeks.
More than a smaller bill
One rooftop solar system quietly upgrades the whole building, for every family in it.
Lower electricity bills
Every unit gets its own metered share of solar. Solar units are free units, so your monthly bill drops from the first month.
Cooler top floors
Panels shade the entire terrace, so the roof stops soaking up heat all day. Top-floor homes stay cooler and spend less on air conditioning.
Longer-lasting waterproofing
The panels shield the terrace from direct sun and rain. Waterproofing lasts years longer, which means fewer leaks and lower society maintenance bills.
A rooftop you can actually use
Our raised structure lifts the panels overhead, turning the space below into a shaded deck for walks, gatherings and celebrations.
EV charging, powered by the sun
Daytime solar is perfect for charging electric cars and scooters in your parking. Your building is ready for the EV you buy next.
See it all on your phone
The Nova app shows each home its solar balance, usage and savings in real time. Full transparency, no arguments, no guesswork.
Real installations, not renders
Every photo here is a roof we have built on. Yours could be next.
Full rooftop coverage on a residential society
The shaded deck residents gain under the panels
SPDUs in the meter room, one share per home
Solar carport with EV-ready parking
Golden hour on a society rooftop
It already works. Families live with it every day.
Scorpio, Fortune Estates in Pune became India's first net energy positive affordable housing building. The SPDU was invented there.
300
flats already powered
100
free units per flat per month at Scorpio
₹0
green premium charged to homebuyers
3
patents on SPDU technology
Taught at business schools
Our first building, Scorpio, is a Harvard Business Publishing case study authored by IIM Bangalore: India's first net energy positive affordable housing project.
Awarded and certified
IGBC Platinum rating, Bharat Leadership Award from the Governor of Maharashtra, and selection among India's top 11 green housing projects by CRISIL under the EU-backed SUNREF programme.
Watch how one roof powers every home
Two minutes that show exactly how Protostar brings rooftop solar into individual apartments.
Hear it from the families themselves
Real residents, real bills, real savings. In their own words.
"Having solar in my flat has significantly slashed my bills. While neighbors from my previous building face soaring electricity costs, I've remained in the lowest tariff slab thanks to the 100 units from solar."
Yogita
Resident, Scorpio - Fortune Estates, Pune
"Living in Scorpio has been a step up for my family because we have experienced a lifestyle upgrade without even trying. Having 24x7 hot water feels like a luxury I didn't know I needed."
Swapnil
Resident, Scorpio - Fortune Estates, Pune
How much can your building save?
Tell us how many flats you have and your average electricity bill. Get an instant estimate of your society's solar savings.
Try the Savings CalculatorOne roof, many meters? We built this for you.
If multiple homes or businesses share a single rooftop, the SPDU can share its sunshine.
Housing Societies
Retrofit your existing building. Panels on the shared roof, SPDU in the meter room, and every flat's bill drops. Work is done in about 3 months with no wiring changes inside homes.
Book a free site visit
Commercial Buildings
Shops, offices and clinics sharing one roof can each get their own metered share of solar. Daytime businesses use power exactly when the sun makes it, so savings are even faster.
Discuss your building
Developers & Builders
Plan SPDU into a new project and sell homes with free solar units built in. A genuine differentiator that helped our pilot earn IGBC Platinum and sell at market price with zero green premium.
Partner with usEverything your society committee will ask
The questions we hear in every general body meeting, answered straight.
Common-area solar only powers the lift, lobby and pumps, so your personal bill barely changes. Protostar covers the full rooftop and uses the patented SPDU to give every individual flat, shop and office its own metered share of solar power. The savings show up on your own electricity bill, not just the society's.
Nothing changes for you. The SPDU automatically switches your home to the normal grid supply whenever solar is not available, with no interruption. Solar first, grid as backup, completely automatic.
Each unit is allotted a fixed solar quota, decided together with the society at design time and enforced by the SPDU hardware. Every unit's share is separately metered, and you can see your balance and usage live on the Nova app. No neighbour can use your share.
Cost depends on your roof size, number of units and structure type, so we start with a free site visit and give the society a detailed quotation. Rooftop solar in Maharashtra typically pays for itself in about 3 to 5 years through bill savings, and the panels keep producing for 25 years.
Solar installation is a society decision, usually passed in a general body meeting per your society's byelaws. We support the committee with presentations, savings workings and documentation to help members decide, and we handle DISCOM approvals and paperwork after that.
Housing societies can avail central subsidies for shared rooftop solar under the PM Surya Ghar scheme, subject to current scheme rules and capacity limits. We assess eligibility during the site visit and handle the application process for you.
We do. Our annual maintenance contract covers professional panel cleaning, performance monitoring and prompt issue resolution. Dust alone can cut generation by up to 25 percent, so maintenance is what protects your savings.
Yes. The SPDU distributes solar to any mix of units that share one roof: flats, shops, offices, clinics or an entire commercial building with multiple tenants.
No. All work happens on the rooftop and in the building's meter room. Nobody enters your home, and a typical retrofit is completed in about 3 months including approvals.
Put your roof to work. Every flat wins.
A free site visit tells your society exactly how much solar your roof can hold and what every home would save. No commitment, no charge.