Planning a rooftop solar setup

[JMP]

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@rdst_1 @adder Any particular inverter and solar panels that you recommend ?

Going to Lithium Ion batteries may take another year or 2 right ? I am thinking of getting the rooftop solar work done while net metering policy still exists in Karnataka (extended till Mar 2021). Maybe I can get a EV in 2021 as well, since 99% of my use is within city <50 km range.

Initially I wanted to go with a 10kw plant, but that would require changing single phase wiring to 3 phase, BESCOM quoted a bomb for that, it would also probably involve tearing down walls to which family won't agree.

The argument made by the installer for micro-inverter is that they come with a 10/25 year warranty and provide better generation even under partial shadow, if I go with a single SolarEdge string inverter then if there is shadow on a single panel output of the whole plant would go down.

adder - any ballpark of when you think you would be able to begin the project ?

i can help you in panels.Buy vikram panels these are really good penals and tried and tested.price you mentioned is insane.a 10kv solar system costs around that much price with tata panels which are most are most expensive one.i enquired about panel for chetansha which he had asked.solar panel prices have gone way down dont get yourself looted.adani mono panels are around 22 and simple one 20rs,tata ones are 25,26rs per watt vikram panel is same around adani.havent used these iq7 micro inverter so cant say anything.we are using solar inverter with batteries so we bring down DC cable from rooftop to solar inverter directly.my cousin have installed one controller like thing it draws 30% extra dc power from panels.sorry i forgot name of that equipment.if you are spending that much money buy 5kv solar inverter with batteries and panels.simply dont pay that much amount

Thanks, even I felt the cost was high. But due to a surgery I cannot lift weights above 5 kgs and hence have to rely on these 3rd party installers. I can do research on approved panels and inverters in my state and buy them, but transporting them and installing them on the roof is beyond my capability.

I have a budget of 3-3.5L for the solar setup and am not particular on any components or panels. Just want to get the best value for my money, with my physical limitations.

 

[adder]

I can only tell you that since you are tied to your installer, go with a inverter that gives long warranty. Solar panels go with the cheapest one you can find from tier 1 manufactures like adani, waree, vikram, etc

 

[NotMyRealName]

How big is this house? Why do you think you need 10KW?

Initially I wanted to go with a 10kw plant, but that would require changing single phase wiring to 3 phase, BESCOM quoted a bomb for that, it would also probably involve tearing down walls to which family won't agree.

Also, 3-phase inside the house isn't as difficult as you think. What are the actual 3-phase using devices you have? A water-pump? What else? For the rest, your 3-phase wiring only needs to be done till your DB. From there, each phase will power a different section of your existing wiring. Even if you want to you cannot use all 3-phases simultaneously with single phase devices.

Below is a photo of the DB in my flat. (sorry for the shit quality but whatsapp messed it up. i dont want to open up the DB cover to take a fresh photo) The red, yellow and blue wires (black is neutral) going into the RCBO at the bottom right corner are coming from my 3-phase meter. They exit from the output top of the RCBO to three different sections. Red goes to the MCBs for ACs and heaters. 20+20+16=56A total. Blue goes to other high load devices like the fridge, washing machine, microwave etc. Combined 54A. And Yellow supplies rooms for lighting and other misc. light loads. About 34A total. That's how 3-phases are distributed in a regular apartment. Main reason for all this is to separate the room line (Yellow) for running on the building generator. To isolate the high loads from running off the gen.

 

[JMP]

Thanks @Julian, the 3 phase devices at home are - fridge, washing machine, dryer, a water heater, a .25 hp water pump.
Planning to add 2 ACs and an EV next year. 2 x 65" TVs and a 1000w desktop power supply are the heavy ones on lighting line.

I'll need to get an independent electrician and plan the best solution for 3 phase I suppose.

How big is this house? Why do you think you need 10KW?

Our actual requirement is around 4 kW, but most states in India have started to remove net metering as it is not profitable for the DISCOMs. So, with plans of having 2 EVs and some additional load in next 5-7 years, I was thinking of getting a 10 kW plant installed so as to lock the net metering for next 25 years.

Taxes and all other charges on electricity are only going to increase from now on as it will start to replace petrol & diesel, the govt will start taxing it badly as more and more people move to EVs and solar.

 

[rdst_1]

Thanks @Julian, the 3 phase devices at home are - fridge, washing machine, dryer, a water heater, a .25 hp water pump.
Planning to add 2 ACs and an EV next year. 2 x 65" TVs and a 1000w desktop power supply are the heavy ones on lighting line.

I'll need to get an independent electrician and plan the best solution for 3 phase I suppose.


Our actual requirement is around 4 kW, but most states in India have started to remove net metering as it is not profitable for the DISCOMs. So, with plans of having 2 EVs and some additional load in next 5-7 years, I was thinking of getting a 10 kW plant installed so as to lock the net metering for next 25 years.

Taxes and all other charges on electricity are only going to increase from now on as it will start to replace petrol & diesel, the govt will start taxing it badly as more and more people move to EVs and solar.

I would like you to recheck all the things that you mentioned as 3-phase because almost all of them would be single phase. I think you are getting confused right now unless you are planning to buy some special stuff that the world doesn't know about till now.

 

[JMP]

Yes, everything I am planning to buy right now is single phase, because I abandoned the 3 phase plan due to wiring change.
But if its not too expensive, I would like to go to a 3 phase connection as it will allow me to have a solar plant above 5kW. The limit from BESCOM is single phase up 5kW, 3 phase from 5 to 10kW.

 

[adder]

Conversion to three phase itself costs a lot, new cables need to laid, new meter, deposits etc. You need to dig to road or footpath and the clearences, it will cost i think around 15k to 20k

 

[JMP]

@adder In your opinion - how much would a 10kW hybrid setup cost today ? (If I start with 0-2 batteries add them incrementally later)
Also, which is the best hybrid inverter in the market today ? (Even if slightly expensive)

 

[rdst_1]

@adder In your opinion - how much would a 10kW hybrid setup cost today ? (If I start with 0-2 batteries add them incrementally later)
Also, which is the best hybrid inverter in the market today ? (Even if slightly expensive)

Any 10kW inverter will be at least 72V or even 120V so it will need at least 6 batteries or even 10 batteries if it is 120V.

 

[adder]

@adder In your opinion - how much would a 10kW hybrid setup cost today ? (If I start with 0-2 batteries add them incrementally later)
Also, which is the best hybrid inverter in the market today ? (Even if slightly expensive)

The max you can get is a 10kw hybrid inverter with three phase output i.e 3.3kw per phase but it requires 4 batteries they cost a lot around 1.9lakh if I remember just for the inverter.
you cannot start with 2 batteries and at the same time get 10kw.
For 2 batteries based inverters you can only get 3.6kw max, you can keep on adding inverters again with 2 more batteries per inverter and get upto 21kw with 6 inverters and 12 batteries. This is where lithium batteries make sense, since a 2x 100ah lead acid batteries can give about 2.4kw max for 30min or 240w for 10hrs, Where as a lifpo4 battery of the same capacity can give you 2400w for 1hr, hell it can give even 20kw for a few mins. So what it means is that you can get a low capacity battery like a 40ah battery but more numbers like upto 12 i.e 2 per inverter and upto 6 inverters. For 10.8kw you need 3 inverters and 6 batteries.

But if you get a 48v system you can get till 60kw via expansion this is assuming you have the space for the solar panels.

But why do you want 10kw of solar, I doubt you have a load that requires that much and fyi with my inverter I run all lcd tvs, fans,lights, 2 x 320+ Liter fridges, 2 x front load washing machines, .5hp pressure pump, .5hp overhead tank pump, 1.5 ton inverter Air con, they can all run simultaneously( with cold setting in washing machine).

 

[JMP]

I don't need a 10 kW solar right away. 5 kW is more than enough for now which is expected to generate 500 units a month, was just planning to have 2X buffer capacity for when we get our EVs. Thought of getting a Nexon EV since most of our usage is within the city, but its a first gen product and has teething issues, also, cars with better WLTP range are expected next year.

Had never thought of hybrid till I saw your posts and calculations, but this makes a lot of sense as well. Won't have to deal with those arrogant BESCOM employee's who need a month to do anything. Discussing it with my family and the integrator.

Is there any Solar Expo coming up ? You'd mentioned about some company which had 4000/5000+ cycle battery pack they had for sale but weren't divulging the kind of cells used inside.

 

[adder]

I don't need a 10 kW solar right away. 5 kW is more than enough for now which is expected to generate 500 units a month, was just planning to have 2X buffer capacity for when we get our EVs. Thought of getting a Nexon EV since most of our usage is within the city, but its a first gen product and has teething issues, also, cars with better WLTP range are expected next year.

Had never thought of hybrid till I saw your posts and calculations, but this makes a lot of sense as well. Won't have to deal with those arrogant BESCOM employee's who need a month to do anything. Discussing it with my family and the integrator.

Is there any Solar Expo coming up ? You'd mentioned about some company which had 4000/5000+ cycle battery pack they had for sale but weren't divulging the kind of cells used inside.

Since solar panels prices are dropping every year, if you don't utilize the kw produced then its a waste to have idle solar not being utilized, even if it means selling power to grid, it will take a long time to recover, considering a 10kw grid tie inverter costs a lot and selling power to the bescom getting paid less per kw vs the high initial cost of the setup.

There was no Solar expo this year in bangalore that was even before covid hit india, there wont be any expos till everyone is vaccinated.

I wanted the seller to just sell me the cells, which they didn't want to nor did they want to tell me who the manufacturer of the cells was so that I can look up the claims in the manufactures website datasheet.

EV adaption in 4 wheelers will start when we get cars with 400km to 500km WLTP range and which costs less then 20lakh on road, I don't see that happening atleast till 2026.
Tesla packs are projected to hit the $100/kw in 2023 but they said they can get it sooner, currently Tesla battery pack costs $150+/kw. Everyone else is atleast 2 years behind tesla in current battery tech that is in production.

 

[JMP]

Since solar panels prices are dropping every year, if you don't utilize the kw produced then its a waste to have idle solar not being utilized

Yup, that's true. Will stick with 5kW for now and wait for better panels and battery tech.

I wanted the seller to just sell me the cells, which they didn't want to nor did they want to tell me who the manufacturer of the cells was so that I can look up the claims in the manufactures website datasheet.

Any chance you remember their company name ?
If its going to cost approximately the same or less than 2x the lead acid battery cost, I can try them out. Even if I go with lead acid now I'll have to replace it in 5-7 years. Long lasting batteries should be mainstream and affordable by then.

EV adaption in 4 wheelers will start when we get cars with 400km to 500km WLTP range and which costs less then 20lakh on road, I don't see that happening atleast till 2026.

Yes, 400+ kms is the minimum requirement if for people who travel or have regular weekend getaways. But most of our family travels within the city. Paying ever increasing petrol and LPG prices is not making sense any more, prices are in no way related to brent and looking at state of govt coffers it doesn't appear they will drop anytime before next elections. So, getting a in-city EV and waiting for a true replacement for ICE with 500-700 kms range after 5 years makes more sense to me.

If you had to buy a inverter in the next month or 2, which would you buy ? Would you still opt for Flin Fusion ?

 

[adder]

Its, Vision mechatronic, and their 100ah (5.6kw) 48v battery costs 1.2lakh last year, which is higher then the DIY option that I was pursing by 2x.

If you had to buy a inverter in the next month or 2, which would you buy ? Would you still opt for Flin Fusion ?

I would have bought directly from china, instead of buying from flinenergy and would have gone for a model which can have parallel function, which is basically two or more inverters working in sync to give 2x to 9x the power in single phase or give three phase( requires 3 inverters minimum).

 

[JMP]

and their 100ah (5.6kw) 48v battery costs 1.2lakh last year

I was just checking OKAYA's site they have LiFePo4 battery with 3000+ cycles, costs about 25K for 80Ah.
But these Vision Mechatronic claim more than 8000 cycles.

 

[adder]

I was just checking OKAYA's site they have LiFePo4 battery with 3000+ cycles, costs about 25K for 80Ah.
But these Vision Mechatronic claim more than 8000 cycles.

Visionmechatronic has cells that are lifepo4 with 4000cycles and LiFeYPO4 which has a claimed life of 8000 cycles, since they didn't say which make cells they use, I cannot believe their specs.

As far as Okaya its too expensive, for that price you can get 3x 80ah lead acid battery

 

[JMP]

I just checked with VisionMechatronics for their Li-Rack Eco (4000 cycles @80% DoD), they offered something called 1 Box which includes batteries + solar hybrid inverter + BMS with active balancing, just need to add panels. Quoted cost 4.6L + shipping for 5.6kVA, which can connect to a 4kW solar array.

Felt its way too expensive. I can get a 5kW grid tied setup with micro-inverters and a conventional 5kVA with 5 x 200Ah batteries + battery replacements after 5 years at that cost. These come with 25 year warranty, their system comes with a 5 year warranty.

 

[ch@ts]

I just checked with VisionMechatronics for their Li-Rack Eco (4000 cycles @80% DoD), they offered something called 1 Box which includes batteries + solar hybrid inverter + BMS with active balancing, just need to add panels. Quoted cost 4.6L + shipping for 5.6kVA, which can connect to a 4kW solar array.

Felt its way too expensive. I can get a 5kW grid tied setup with micro-inverters and a conventional 5kVA with 5 x 200Ah batteries + battery replacements after 5 years at that cost. These come with 25 year warranty, their system comes with a 5 year warranty.

Isn't the 25 yr warranty just for the panels?

 

[JMP]

Nope, both Enphase and SolarEdge inverters come with a default 10 year warranty, extendable to 25 years at a small additional cost.

 

[JMP]

@adder @rdst_1

I was looking into this further to get options available for my setup. Here is some components and data I came across...
(As you guys pointed out I will stick to 5kw for now)

1) Found a few other hybrid inverters which support both high and low voltage batteries. Growatt - Low / High, Huayu - this is marketed as Cellcronic (Galaxy 6G), there are some videos on Youtube explaining its features. They allow you to use lithium or lead acid batteries, select the max grid feed and have a 5/10 year warranty. Have contacted Growatt distributor to know if they can import a specific model for a few users.

2) A company Hykon from Kerala assembles LiFePO4 batteries in India. They've launched SAFE series of batteries which cost 31K for 100Ah, about 50% higher than Exide Solatron batteries which are the best lead acid ones. Cells used internally are mentioned and have 5 year warranty. Pricing is better than Vison Mechatronics.

3)BiFacial solar module from Vikram and Waree rated at 400w for front which can go up to 480w are available for 8-9K in the market. These can be useful for folks with less rooftop space.

4) Enphase micro inverters price has come down to 7K for 'IQ 7+'. Apparently some new Chinese hoymiles micro inverters are available in India as well, with 12 year warranty, have 2 - 4 MPTTs and can be used with 2-5 panels depending on the wattage. Huayu ones are apparently available in India as well.

5) Cost of 5kVA external battery inverter, in Bangalore, is approximately 30K, 3.5kVA is approximately 15K

Other thoughts ------

Disadvantages of going off-grid ->
1) I won't be able to use the grid as a power bank. The grid allows us to bank and use power generated anytime during the same financial year. Eg: If I have high generation in March, April, May and minimal generation in December, January, grid allows us carry over that balance. If I am on a vacation where not much power is being used it goes into my account, where as its wasted in a offgrid system.

2) Can't use power generated to charge my EV. Most of us use our vehicle during the day time so the power being generated and the time at which the vehicle is standing idle is the exact opposite. Having a second power bank to charge the vehicle via stored energy is neither economical nor efficient.

Problem going hybrid right now -> (Bangalore specific)
1) No BESCOM approved hybrid inverter is readily available, only one I could find on the list was 10kW which is very expensive.

2) VFM Chinese hybrid inverters exist, but no idea if they will ever get approved in future. (Add to that the growing anti-china sentiment).

3)Shorter warranty and lower efficiency on hybrid inverters.

So, I am still confused on which way to go, exploring for now.....
Do you guys have the link for MNRE approved inverters with you by any chance ?