[dkaile]

Originally Posted by ashkamath

Is this possible to get installed in apartments?
Do you think it's possible? Our apartment roof is covered with the sheets and would they be able to take the weight of the solar panels? I am thinking of taking the services of a local electrical contractor and get it done.

Definitely possible. I have seen it installed over cement/metal sheet roofing. Rest you will need to know the strength of your supporting structure.

Originally Posted by itspatra

Is the solar panel cleaner required? Wouldn't the the occasional rain clean the panel. I thought those are for dry and dusty areas like deserts. Also wouldn't a cloth work? I am just curious.

As you can see in our setup, the panels are at a height and not easily approachable to clean with a cloth. Water and a long wiper is needed in our case along with a ladder. Just 2 months after the monsoons, a heavy layer of dust had settled on them and I got it cleaned last week with 2 buckets of water and the wiper that I got from Amazon. So depends on the weather in your area, if it rains every month or not.

Originally Posted by samitjain

Can someone suggest a vendor for rooftop solar system, I don’t have any expertise to do it myself. If someone knows some vendor in Delhi it would be helpful

Tata Solar ;
Rinova Solar Power Pvt Ltd. Kindly search contact details online.

Originally Posted by efgritesh

On this, are we suggesting loads like 2 AC''s "off Grid" or "on GRID"?

Off Grid.

On Grid systems have a major disadvantage, that they stop working the moment electricity supply goes, as it does everyday in our area. If you get 24 hours uninterrupted supply in your area, then On Grid is the default choice. Unfortunately, in most parts of India, that is not the case. And in the event of a holocaust (just joking), you will still have your own over the roof power supply - Lolz.

Originally Posted by aashishnb

Can I ask you for some key pointers with regards to materials to use and why.

For e.g.

1. Which type of battery to use & why (longevity) - use ones with 5 years warranty instead of
2. Which type of PCU - copper instead of aluminum, as will last for 25 years.
3. DC MCB instead of AC MCB
4. What type of cables
etc.

I think I mentioned quite clearly why I used Lead Acid Batteries instead of Lithium Ion in this setup. I went with Exide because that was the most leading brand and went with the 5 year full warranty ones, because the manufacturers make them better and heavier to last their full term and beyond.

Or why I used the Solar PCU of a particular brand. It is all quite clearly mentioned in the comparative spec sheet. Or why I used DC MCB in the DC circuit coming from the solar panels. Or why I used DC cables in the DC circuit. You can use any good quality brand on the AC side cabling like Finolex, RR, Havells etc.

If you have any specific query, you can let me know.

Cheers...

[aashishnb]

Originally Posted by dkaile

I think I mentioned quite clearly why I used Lead Acid Batteries instead of Lithium Ion in this setup. I went with Exide because that was the most leading brand and went with the 5 year full warranty ones, because the manufacturers make them better and heavier to last their full term and beyond.
Cheers...

Sorry, looks like I did not come across clearly. I did see your reasons, which is why this thought came across.

What I was trying to ask if if you can help with key pointers (like a checklist we have for cars). This may be summarized in a separate post so that someone who may not be able to read the entire thread can use it while deciding.

Thanks.

[dkaile]

Originally Posted by aashishnb

What I was trying to ask if if you can help with key pointers (like a checklist we have for cars). This may be summarized in a separate post so that someone who may not be able to read the entire thread can use it while deciding.

In today's 'lack of attention span' world, your query seems plausible. Though I would strongly suggest anyone interested, to read the thread or any related informational material carefully.

As every rooftop is different, so then would be it's solution. I have just provided general guidelines as to how I did it and if someone is able to replicate, then good for them. There can never be 'one size fits all' solution.

I am no professional installer and learnt as I went along. Some general guidelines that I can summarize from my experience -

1. Always use 'hot dipped' GI structure. It lasts longer. Semi hot dipped is also available and that may work out cheaper if there are budget constraints. Use stainless steel bolts wherever possible to avoid rusting. Use crush washers for proper tightening of the structure along with normal washers.

2. Always connect the solar panels to your wiring going into your DCDB box with MC4 connectors, never by splicing any wires. Learn how to connect MC4 connectors properly by hundreds of online guides or even by sellers on Amazon.

3. Get high quality Solar panels. Don't choose local fly by night operators. Don't use outdated P-Type panels (that Tata Solar still supplies IIRC). For those looking to getting subsidy on their on-grid systems, they need to use DCR Panels. These are 'supposedly' fully 'Made in India' till the cell level. Though I seriously doubt these claims. Also initial quality levels of these DCR panels was suspect in comparison to Non-DCR panels, which are partly assembled here with many key components (read Solar Cells, aluminium frames, tempered glass etc.) from abroad (read China and Germany). Also the cost of DCR panels is higher than Non-DCR ones, surprisingly! So in the overall scheme of things, you loose a substantial amount paying much higher for these DCR panels from the subsidy that you will eventually receive. I have used all Non-DCR Panels as there is no subsidy on off-grid systems and their quality is much higher at lower costs.

3. Buy high quality Solar PCU. Taking into account the voltage fluctuations and power supply in your area. Copper Transformer based one's are 'supposedly' much better, to cope with voltage irregularities, though the difference is decreasing with newer technologies coming in. Check the components and PCB's used by the solar PCU manufacturer. They should be of high quality from reputed suppliers. If you can, look closely at things like the Fan's inside the PCU, Quality and type of relays, MPPT components which convert Solar DC voltage to AC, quality of wires used inside out and of course the type of transformer used and it's build quality etc. Avoid PWM based solar converters as that is now dated technology. Hybrid PCU's are also coming soon/ are already here (which work both as off-grid and on-grid). But either they are mostly by Chinese manufacturers, with no control on actual quality levels and warranty or are prohibitively expensive (2-3 Lacs for a 5KVA one) from EU/Swiss/Germany based manufacturers. Buy Solar PCU's which can SURVIVE Indian Electric Supply conditions.

4. Buy High Quality Wiring whether DC or AC which provide proper (read FULL) gauge of wiring specs mentioned. Try to avoid using AC wiring on DC circuit and vice Versa. Same goes for MCB's used. Use minimum 6mm DC wire to connect the DCDB box to your Solar Input in the Solar PCU, 10mm would be better in case of 5 KVA systems. And Minimum 4mm DC wires for the strings connecting the solar panels to the DCDB box, 6mm would be better. Place all wiring in Conduit Pipes and never directly in the open, for longer life and protection from the elements. They will last twice as long.

5. Read all specification brochures of the Solar Panels and PCU's completely and thoroughly to avoid making basic installation mistakes.

6. All solar structure should be sturdy and properly attached to your roof so that it does not get blown away in stormy conditions.

7. Proper Earthing's are a must. Don't compromise on separate and fully isolated Earthings for Lightening Arrester, Solar DC Structure and AC side Earthing. Use grounding rods with earth pits and high quality conductors (wiring). Don't forget to Earth the DCDB box at the Surge Protector level (refer my connection picture of the DCDB Box).

8. Keep your Solar Panels clean.

Will keep adding as and when I remember more points.

Cheers...

[varkey]

Thank you for posting this thread, this is extremely detailed and helpful.

I have always had this question with respect to the efficiency of solar generation in an off-grid setup. I think in your case, you have used 2x200 Ah batteries which would mean about 4.8 kWh of energy storage. However being lead acid batteries, you cannot fully deplete it, so maybe around 2.5 kWh of useable storage (ignoring any conversion losses).

Now, with ~3.5 kW solar panels, you'd have around 15-18 kWh of daily generation capacity. However, in case you are not able to use the energy as generated, considering the limited storage capacity, most of your generation capacity would get wasted right?

When possible could also share the daily solar generation numbers (kWh)? Comparing the two bills you shared, there is a drop of around ~ 700 kWh which seems to be on the higher side for a 3.5 kW off-grid setup. Was there some other change in usage pattern?

I have this 1.2 kW off grid setup, with 2x150 Ah batteries and a 2 kW solar PCU from UTL, and I find that generation capacity during the day gets wasted, as the day time load is less. In this case though, I have not connected the refrigerator, which I think is one of those loads which can help with usage efficiency. You mentioned adding a capacitor to avoid tripping the solar PCU, could you please add more details regarding that, as that is one of the reason I didn't connect to the refrigerator. The compressor start peak current draw causes the PCU to overload especially in the evening time when solar generation is low.

Originally Posted by ashkamath

I am thinking of installing a 4 KW (sanctioned load)solar system for my apartment in Mangalore, Karnataka. It's a small apartment complex with 16 houses (4 floor with 4 houses in each floor).

I don't see a technical feasibility issue, but how would this play out with the other owners, as the sheet metal roof and terrace would be part of the common area, every owner would have rights over. Would the other owners be okay to let you use a common space for individual benefit? Or are you thinking of coming into an agreement with all owners to get complete roof rights or an equal share of the roof and then install the panels only in your designated area?

[alto'tso]

Can you provide the link for solar panels bought from amazon

[lejhoom]

Originally Posted by dkaile

Continued...

This is riveting. Years ago while marking my house I understood there are umteen things to know about every aspect of home building. Electricity is one I couldn’t wrap my head around. Then a few months ago,I too got this solar thing installed. Major difference I noticed is about the electricity bills. I pay a pittance now.

A couple of things piqued my interest from your thread. 1. The cleaning rod. I didn’t know about cleaning the solar panel. Do I need to buy some kind of pressure washer also?

2. What should be the ideal TDS reading of battery water? I don’t have battery in the set up. Just a casual query.

Thank you.

I got the answer from Amazon.

[Guddu_Bhaiya]

Regarding TDS reading of battery water, we follow in our manufacturing process is less than 2.5 PPM. We also manufacture DM water to be sold with our lead acid batteries.

PS: I am working in R&D dept. in one of largest manufacturer of lead acid batteries in India.

[dkaile]

Update - The system is working perfectly 6 months down the line. Zero downtime. Saving at least 3~4k bucks every month on electricity bills.

Cheers...

[Guddu_Bhaiya]

Originally Posted by dkaile

Update - The system is working perfectly 6 months down the line. Zero downtime. Saving at least 3~4k bucks every month on electricity bills.

Cheers...

Wonderful to know.

Just wanted to ask whether you have got required DM water for your batteries.
If not, would like to suggest our In-House manufactured DM water.

[Guddu_Bhaiya]

Originally Posted by dkaile

Solar Plant Setup on my Rooftop - Off-grid (for now) - 3 KVA


As is evident in this picture of the mains Ampere/Volt meters, that I have attached after our electric supply meter, the normal light load is about 650~700 watts and the maximum power load including 2 refrigerators etc. is about 850 watts, excluding the Air Conditioners. So the minimum total solar system needed to be capable of outputting 1550 watts.

Attachment 2686786


Continued...

Just wanted to know that whether maximum power load of 850 watts also includes running load of washing machine as same will be running in day time or not.

[dkaile]

Originally Posted by Guddu_Bhaiya

Just wanted to know that whether maximum power load of 850 watts also includes running load of washing machine as same will be running in day time or not.

No, the power load does not include any heavy loads like the Air Conditioner, Deep Freezer, Geysers or the Washing Machine.

Cheers...

[x-o-b]

Hi, how long would the batteries last and what would be the cost of battery replacement? Also deterioration of battery performance over time, how does that factor in?

Lastly, what are your provisions for cleaning the panels?

Thanks for the beautiful detailed post.

[dkaile]

Originally Posted by x-o-b

Hi, how long would the batteries last and what would be the cost of battery replacement? Also deterioration of battery performance over time, how does that factor in?

Lastly, what are your provisions for cleaning the panels?

The Exide batteries that I have purchased have 5 year full replacement guarantee, no questions asked. Details already provided in the posts above. They should easily last 7~8 years. All battery replacement costs are factored in and since they are quite heavy lead acid batteries, their scrap value is also very high. No such deterioration noticed in the one year that has been completed.

Panel cleaning tools have also been detailed in the posts above. But I see that a spite of rain every 3~4 months, also does a good job of washing off the dust off the panels.

Cheers...

[fordday]

Does it need inspection and certificate from authorities as in our household wiring ?