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Wow, something like this will neutralize all the savings a solar plan would generate... I only wish they don't every do anything crazy like this in TS. Right now here in hyd, the discom isn't even too bothered about Maximum demand. Meaning, if you have 1KW sanctioned load and you end up putting 3KW max load, they don't bother much for domestic. However, i know that they are appropriately sizing new connections before hand but there is no Monthly fees per KW sanctioned load, it is only a 1 time fee.

In fact, i was thinking of increasing my Sanctioned load to 10 KW (from 6 kw) by paying the 1 time fees now since i predict they might get a bit strict on Max demand in the near future when every home starts getting an EV and charging at home. I could always upgrade when that situation arises but by guess was that they would increase the one time fee and then might not also have the DTR capacity to issue more sanctioned load in the future.

But thinking about fees per KW sanctioned load, i don't feel like increasing any sanctioned load now since it is definitely a possibility that this fees will come into picture sooner or later.

Does anyone know if the 20-25 year contract with the discom for on grid solar can be terminated without any penalty?

Pardon my ignorance, but I am under the impression that 'on grid with net metering' and 'power back' viz. comprising of an inverter and battery, are mutually exclusive. You either have net metering or power back. Not both.

We live in Hyderabad where the power supply is quite regular except for short duration outages because of tripping of feeders/transformers. Additionally, we have a large roof that receives ample sunlight though it faces southwest.

Based on your aforementioned comment, it appears that I can have my cake and eat it too. In other words, it is theoretically possible to have a power back up to tide over an occasional outage whilst at the same time install solar panels that feed power into the grid. Is my interpretation correct?

With "power backup", I meant regular power backup (regular sinewave inverter and battery) which many people have at home. With on grid solar, the power generation stops in case of power cut, at that time, this power backup get used - similar to when you face normal power cut. If there is a longer power cut and your battery dies out, you will be out of backup power even in day time, since solar panels won't work without external power source.

In hybrid inverters, power is generated even when regular power supply is not there as long as sun is shining.

I am aware that 'power backup' is dependent on the Ah capacity of the battery. Bigger the capacity, the longer the duration of the backup in case of a power cut. This is the most common system used in most households in areas susceptible to power outages.

I also am aware of the hybrid inverters that charge the battery either using solar energy when sunlight is available and at other times, power from the mains.

Lastly, the solar power generated can be fed to the grid and the consumer receives a rebate.

As per my understanding, the second and third options are mutually exclusive. Either you consume the solar power or you feed the grid. Not both. Right?

Where I require clarity is regarding feeding the solar power generated by me and at the same time installing a regular power backup. I would appreciate your inputs in this regard.

No its not exlusive, in day-time, the power generated is first used by house and only extra power is exported to the grid. If the power generated is not sufficient, the difference is imported from grid.
Solar net meter is bidirectional, where it records both imported and exported units for billing purpose. The units consumed by home generated from solar panels are not recorded in the meter.

• Installed capacity cannot exceed sanctioned load on meter.
• Anything above 5kw will have to be 3 phase.
• Fixed charges remain on bill.
• GST should be added only if there is a bill to be paid.

Sample bill Calculation:
Units imported from Bescom = 100
Units exported to Bescom = 300
Fixed charges = Rs500
Your bill, assuming your PPA rate is 3.99 = (300-100)*3.99-500= Rs298 Deposit to your account

Net meter billing is still not automated/system driven - at least in my subdivision. No online bills and neither does it reflect properly on bill portals like your banks/amazon etc. Its excel driven by an individual sitting in the bescom office and you get a print out dropped at your house. There are always adjustments added and subtracted in the billing and I have never been able to tally or reconcile it, any queries on billing requires a visit to your Bescom office and the customer support will not be able to help on net metering bills. I would strongly suggest you speak to your vendor and make him responsible for first 3 bills - they have better connects and agents who can sort out any issues.

I am somewhat confused and I guess it's because the question has not been framed correctly by me. As such, for the sake of clarity, lets keep hybrid solar system out of the equation and focus on net metering and normal backup.

If I understand correctly, when we opt for net metering, the power generated by using solar panels installed by the consumer is fed into the grid and the billing is based on the net difference between the units consumed and the units fed into the grid.

If we opt for such a system, i.e. net metering, can we simultaneously install a normal backup comprising of a sine inverter/battery to tide over short duration outages because of the tripping of a transformer, etc.?

You are correct. Here's a simplified explanation.

• You intend to install an on-grid system which will export power to the grid.
• The on-grid system consists of panels, a solar inverter and a net-meter.
• The solar inverter converts DC from the panels to AC for export. This is not a backup. It just happens to be called an inverter, causing confusion for some. This will be a separate unit installed outside your house.
• The net meter will work just as you have described. Let's say you generate 20 units and you consume 25, you will be charged for 5. However there could be some ifs and buts in every state so please check with your vendor.
• Check with your DISCOM on how excess units generated by you is settled. In Maharashtra, extra units generated is rolled over every month until March and then is made zero. April is a fresh start. We do not get paid. It might be different in your state.
• You always consume power from the grid in an on-grid system and not directly from the solar system. In places with fairly consistent power, on-grid systems are preferred because of their simplicity, lower cost and low maintenance.

To reiterate, there are two inverters:

The solar inverter
Part of the rooftop solar system. Installed outside. Converts DC power from the panel to AC for export.

The backup inverter
This is not a part of the solar system. This is the standard inverter backup with batteries that most houses have which gives you backup when there is a power outage.

The two systems are completely independent. You can install a solar system from company A and a backup system from company B. It doesn't matter.

Please reach out to a local vendor and he will explain this to you in a great degree of detail and provide State specific information that will help you make your decision.

As Ranjith has answered, yes you can have a normal backup inverter for power outages.
Sorry for the confusion, normal backup is part of your household electrical circuit. As far as solar panel/ solar inverter is concerned, its irrelevant.

I'm not sure if writing more will make it more confusing :coldsweat but consider power discom's supply and solar panels supply as two sources of power to your house. Whatever appliances (including normal inverter backup) you run in your home doesn't matter. They will run (in case of normal inverter, charge) from whatever power source is available to it. In case of power failure, both outside power source (DISCOMs or solar) won't feed in, and your normal inverter will kick in as it happens in normal households during power cut.

If you already have normal power backup, you don't need to do anything extra. Both solar and discom's input feed in to your main power fuse just after your meter.

Correct. Just to add to the above, in my case, I already had a traditional UPS system at home. When I installed the solar system, it just worked. The older ups system does not know anything about the new solar inverter.

Thanks for the clarification. As suggested, I will approach a local vendor.

I lived in Mumbai before moving to Hyderabad. In Mumbai, normal backup is not part of the household electrical circuit. At least not whilst I lived there. Hence the confusion.

I like the way you put it. ;)

Now that this issue has been resolved thanks to all of you, I can get down to the nitty gritty of deciding capacity, vendor, etc. Will continue to raise queries as we go along.

Many old houses do not have it... In the most simplest of setups, It's like a 1 day work for a electrician where he separates all critical loads like main lights and fans and then merges all these at a single point in the main junction box. The normal backup inverter output is then connected to this single wire. The existing neural line is used as it is.

You may be right, because we lived in an apartment block that was constructed over 60 years ago. The wiring was not concealed; wooden battens with rubber coated wires held in place be metal clips.lol:

As regards Hyderabad, can you suggest any vendors who can undertake the installation of solar panels with net metering?

I got my system installed by a vendor called Kehansri Technologies ltd. They are authorized vendors for Tata solar and i am happy with the overall work other than the minor hiccups and follow ups here and there. i think it took slightly over 3 months from the date i paid advance to installation. Installation itself takes 3 days max, rest of it is all paper work, approvals and logistics. You can google to find contact details. I directly approached TATA power solar and they referred this vendor to me.

Get your Sanctioned load upgraded to the size of the system the vendor recommends before hand since it usually take about a month. can be paid for and applied from tsspdcl website. this is outside the purview of the pv system cost. the vendor will apply this for you but will charge you separately but then you will also pay him the advance along with this and your waiting time might seem longer. All other fees are included in the vendor cost including chai pani.

Tsspdcl will finish their part of the approval within a week. that approval is them submitted to tsredco for subsidy request. this took almost 40 days for approval. Then the vendor placed an order for the system with tata which arrived in like 15-20 days.


You can find the approved vendor list on the tsredco website and can try a few vendors and figure out who works out better for you.
https://tsredco.telangana.gov.in/Upd...st-Batch-3.pdf
https://tsredco.telangana.gov.in/Sol..._payments.aspx

A few pointers:

You only need to go with these vendors if you need the govt subsidy.

40% of benchmark cost for 1-3kw PV system
20% of benchmark cost for 3+-10kw PV system

I highlighted the benchmark cost because that's the govt approved price and vendors are "supposed" to follow it. However, the reality is that no vendor will install at anywhere close to that price. to give you a perspective by 6KW grid connected system costed me slightly over 3L all inclusive (pre gst & price hike pricing). And the vendor would directly get approx 76k as the subsidy amount (for 6kw) on top of what i paid. However, My system also included 8 feet elevated structure which is not covered in mnre benchmark costs. but even i consider 30-40 k for the structure.

The limitations of going with subsidy is the system comes as a package and you cannot customize. 335W panels, while you can now get 440 and 530watt panels. inverter size exactly inline with size of the system leaving no room for future upgrade. Or get something like a hybrid inverter that can send back to the grid as well and store energy in batteries (which you can get later).

I have recently seen the approved panels lists here and there are larger W panels in the list but the vendor gave me some stupid reasons and said 335 is what i'll get.

https://mnre.gov.in/public-information/current-notice >> Check 5th apr publication

I realized i have been typing a long post and will stop here but reply back with your specific questions and i will answer later.

In the past eight days, my 3KW system @ Hyd is showing a peak generation of 2500..3000W (83% to 99.8% of installed capacity), a sudden departure from the previous average high of 1800w? I guess the panels are washed in the rains and are more efficient in the cool climate, but want to confirm if others are also seeing the same kind of numbers.

On the same note, the total generation on Jun/15 was 25.3 units, while for the rest of the month so far the max is 15 units. I am wondering if this is a malfunction of the system or can a 3KW system generate 25 units on a day with clean panels, good light and cool climate?