[graaja]

Solar Power for Irrigation and Electricity at Farm

Three years back, I had bought a small piece of barren land of 1.5 acres with the dream of converting it into an orchard with a farm house. At the time of purchase, the land did not have electricity. Initially, I was planning to get grid power. Bringing electricity would involve installing 6 or 7 electric posts at own cost. Instead, we decided to go green with solar energy to power the farm.

The installation of a farm house has been documented in another thread.

Installed - A Container Home at my Farm

This thread is to document the electrification of the farm using solar power for irrigation and electricity for the farm house. Completed this work in two phases.

Phase 1: Solar Pump Installation (April 2021)

This was a straightforward installation.

We had drilled a borewell and struck water at about 200 feet. Decided to go with a 3HP pump placed at a depth of 250 feet. Following are the specifications of the components used.

Solar panels: 3.35kW (10 x 335W)
Model: Waree WSM-335
Power: 335W
Open circuit voltage: 45.8V
Short circuit Current: 9.5A

Drive: INVT GD100-004G-4-PV Variable Frequency Drive
Output voltage: 220V
Rated output power: 4kW
Rated input current: 13.5A
Rated output current: 9.5A

Pump: CRI 3HP submersible pump
Rated voltage: 220V, 3 phase
Rated Current: 10A
Water delivery: 7500 liters per hour

The pump was custom built for a voltage of 220V. Standard 3 phase pumps are rated for 340V or 380V, and would require at least 12 panels in series connection to generated the desired difference voltage between the pump and the solar array.

The installation was done by Nego Renovation and Mechatronics, a company in Coimbatore. This is a one man company run by Mr. George. I am very impressed with his knowledge about solar systems and also the quality of his work.

Following picture shows the block diagram of this system.



Following pictures show the installation of the pump.

Materials arrive at site.


Frame being assembled. The frame is designed to provide an angle of 11 degrees (the approximate latitude of the location of the farm) to the horizontal, facing due south.


Concrete mixture poured for the legs.


Waree solar panels.


Panels being assembled on the frame.




Panels assembly completed.




Submersible pump assembled.


Pump lowered into the borewell.


The INVT variable frequency drive. The drive displays the frequency at which the pump is being run. The frequency varies anywhere between 10Hz to 45Hz based on the intensity of sun. The pump speed and hence the water output varies with this frequency.


Water delivery. Did a rough measurement by measuring the time it takes to fill a 10 liter bucket. From this rough measurement, the output is about 6000 liters per hour.


With this, phase-1 of the installation came to a conclusion. The total cost of installation worked out to 1.83 Lakhs which included the panels, frame, pump, VFD, and installation charges.

Below are a few advantages and disadvantages of solar for irrigation.

Advantages:

• No need for grid supply.
• Other than the installation cost, there is no additional cost for energy to run the setup
• Very useful in remote locations where there is no access to grid supply
• No worries about power cut. In rural areas, they usually cut off one of the phases for almost 18 hours of the day.

Disadvantages:

• Delivery of water varies with intensity of sun
• Variable pressure in the system based on intensity of sun
• During monsoon, water output will be very less. This is not a problem for irrigation as monsoon will take care of watering the plants. But pumping water for the farmhouse will be a problem

Because of the variable water delivery and pressure, a solar based borewell system is not very suitable for drip irrigation. To overcome this shortage, usually people build a buffer tank of 10k or 20k liters and fill this tank using the solar pump and then use a pressure pump to irrigate the field from this buffer tank. I have not done this yet. Instead, I have split the whole farm into 6 zones and have provided valves to control water to each of these zones. On a sunny day, the pressure in the system is more than enough to irrigate one or two zones at a time. In the future, I have plans to build a buffer tank and to automate this system with electrically operated valves and a PLC.

[graaja]

Phase 2: Solar Inverter Installation (March 2022)

Phase 2, the installation of solar inverter was completed last week. We had a small 300W solar panel and a single battery system to power the lights and fans in the house. With the 3kW inverter installed in phase 2, we will be able to power all appliances like fridge, water heater and an AC (future upgrade).

This phase was a little tricky. The idea was to re-use the same 3.35kW panels to generate electricity. The pump would be used only two days a week for a few hours. The panels would power the inverter the rest of the days.

We needed to switch the panels between the pump drive and the inverter. For the pump, all the 10 solar panels had been wired in series which resulted in a maximum open circuit voltage of 458.5V. Almost all the solar inverters that I came across worked at less than half this voltage. This would require rewiring the panels using complex multipole switches. One of the configuration will be with all 10 panels wired in series as a single string and the other configuration would be with 2 strings of 4 panels in series (2 panels will be unused) with the 2 strings connected in parallel. As we needed DC switches rated at 250+ volts and 10+ amperes of current (DC switches are much more expensive than the AC counterparts), and also run DC wires from all the strings to the control room, this was working out to be a very expensive affair and also a complex system.

That is when I came across a company Flin Energy which had a product called FlinFuzion that could take 500V DC as solar input and charge a 24V battery bank using MPPT algorithm. This would greatly simplify the switching circuit. We now need only a simple two way changeover switch without any change to the solar array configuration. The inverter also had an overload capacity of 200% which would support loads with high startup current like AC or a pressure pump in the future.

For backup, decided to go with 4x 150AH Exide Solar batteries configured as two strings of 24V each. This battery bank has a theoretical storage capacity of 7.2kWh of energy which should provide 2 to 3 days of backup power to the house.

Solar Inverter: FlinFuzion 3kVA
Output power: 3kVA
Surge power: 6kVA for 5 seconds
Efficiency: 93%
Maximum PV array input: 500VDC
Maximum solar charge current: 80A

Product Link: https://flinenergy.com/product_detai...Solar_Inverter

Following block diagram shows the final system.



A few pictures of the installation of the solar inverter.

As the house is located about 300 feet away from the control room, we installed 5x 10' high posts to bring electricity from the control room.

Posts installed. The posts are 10 feet high above the ground and 2 feet under the ground reinforced with concrete mix.


Wires routed through the posts running to the control room.


Connection to the house.


Installation in progress. We temporarily connected two batteries to the inverter and used the inverter to power the power tools.


The FlinFuzion inverter. To the left of the inverter is the MCB for the 230V output. Further left is the DC junction box with DC switchgear and fuses for the solar PV input to the inverter. Below the inverter is the switch for the battery.


The display on the inverter provides lots of information like battery voltage, charging current, solar panel voltage and current, output voltage, load, system power flow etc.


The complete system with the 4 batteries.


The changeover switch to the left and the pump controller on the right. All wires are neatly wired through the wire tray.


View of the solar panels.


View of the house from the solar panels.


The total cost for this phase worked out to be around 1.7 Lakhs that includes the inverter, batteries, switchgear, posts, wires and installation charges.

With this installation, the complete farm is now powered with solar energy.

Future upgrades possible with this system:

• Add a 10k liter buffer tank and fill this tank from the solar pump. Use a 1HP pressure pump that will be powered by the inverter system to pump water from the buffer tank. This will provide higher pressure in the system and can irrigate multiple zones simultaneously. This can also be used as a place to soak on those hot summers.
• Add an irrigation automation system that can be powered from the solar inverter
• Add a 1.5 ton inverter based AC in the farm house for those hot summers.
• Add LED lights on the posts to illuminate important areas. Right now, except for the lights in the house, the farm is totally dark in the night.

That's all folks, I have for now!

[Aditya]

Thread moved out from the Assembly Line. Thanks for sharing!

[megazoid]

Extremely informative and useful writeup. Thanks for taking time to pen this.
Technicalities apart, this journey of getting things working from ground up is perhaps one of the collateral joys of having such a place.

More power to you!

[graaja]

Originally Posted by megazoid

Extremely informative and useful writeup. Thanks for taking time to pen this.
Technicalities apart, this journey of getting things working from ground up is perhaps one of the collateral joys of having such a place.

More power to you!

Thank you so much for the kind words, Hari!

Very true. The satisfaction of seeing the incremental improvements and transformations is an experience that can't be described in words

[sandeepmohan]

Originally Posted by graaja

Add LED lights on the posts to illuminate important areas. Right now, except for the lights in the house, the farm is totally dark in the night.

Not that it should matter under this particular application as you have solar installed. You get to buy solar led garden lights that have their own charging panels built in. All they need is to be mounted on the post and you're sorted. No wiring to be drawn from the power line.

Thanks heaps for sharing the overview of this project. Anything that is renewable, sustainable piques interest. I will float the idea to my folks to generate some of their power using the sun.

[amvj]

Thank you for posting. It is very interesting to see the articles in Team-bhp.

How deep is that borewell and what was the cost?

On another note, is it possible to install a hand pump on (existing) borewells that are rather deep like 300ft?

Edit: these seems to designed for less than 30m deep.

Are there any guide for hand pumps and any good brands etc ?

[ninjatalli]

A few basic question(s)

- why not have more height to the stilts holding up the solar panels? You could keep it around say 10 feet (or equivalent to normal shed ceiling height) allowing someone to go under (e.g. for some temporary storage setup later). I have seen this low-key setup at many places and always wondered about it.

- is the location of the solar panels (seems to be closer to your land's boundary further away from the house) more aligned to the water pump setup? Or say where the water levels are relatively higher? If not, wouldn't setting it up closer to the house avoided the cost for the poles to be setup?

- How come there are no trees/shrubs between the panels and the house? Not the part of land that you have irrigated yet? Or rather seems like a (future) grass/garden area

Happy to see this coming up nicely bit by bit

[libranof1987]

Terrific stuff, graaja. This should help several people, given the rising popularity of both solar adoption, and farm/weekend homes.

1) How consistent do you anticipate the solar power generation to be through the year - will it generate enough to last your needs through winter/monsoon?

2) Will the power generated last your needs - home appliances, water motors and so on. Esp. with possible fluctuation in generation.

3) Someone has mentioned on another thread that efficiency drops as dirt/debris accumulate on the panels. Do you plan for an automated washing solution? Luckily your panels are easily accessible so manual cleaning should be easy - but not when you're away for extended period of time.

4) Noob question but how is excess generation handled since you can't send it to a grid? I'm assuming generation may be >> consumption + battery storage. Or would the circuit cut-off?

[skumare]

Very well done, I guess the service providers also deserve accolades for such a professional installation.

I am evaluating options to install a solar system along with 7.5HP open well motor in a farm well, focussing on if we could go for a DC motor rather than the normal 3 phase AC one. Did you evaluate the option of a DC motor? Pls share your thoughts.

[chinkara]

Originally Posted by ninjatalli

A few basic question(s)

- why not have more height to the stilts holding up the solar panels? You could keep it around say 10 feet (or equivalent to normal shed ceiling height) allowing someone to go under (e.g. for some temporary storage setup later). I have seen this low-key setup at many places and always wondered about it.

I was told by a solar engineering company in Indonesia I did some work for that the higher the frame height the more the chance of storm damage and accordingly the thickness of frames etc. So cost increases exponentially.
Not sure if this is true for graaja, but maybe the same logic holds here.

[naveen.raju]

Originally Posted by ninjatalli

A few basic question(s)

- why not have more height to the stilts holding up the solar panels? You could keep it around say 10 feet (or equivalent to normal shed ceiling height) allowing someone to go under (e.g. for some temporary storage setup later). I have seen this low-key setup at many places and always wondered about it.

We did something similar. Now there's one huge room where we have a table, chair, bed etc.

Couple of things - It's an extra expense (ours is around 15 feet high) and hard to clean the panel during maintenance. We installed 3-4 years back and the guys did find it difficult to clean them.

[graaja]

Originally Posted by sandeepmohan

You get to buy solar led garden lights that have their own charging panels built in. All they need is to be mounted on the post and you're sorted. No wiring to be drawn from the power line.

Thanks heaps for sharing the overview of this project. Anything that is renewable, sustainable piques interest. I will float the idea to my folks to generate some of their power using the sun.

Thank you for the kind words. Initially, I was planning for solar based lights. But as most of the power generated will be unused, I thought of using lights powered by electricity. As the wire is running along the posts, it does not require any extra lengths. Still there are a couple of remote locations where I plan to install small solar based garden lights.

Originally Posted by amvj

Thank you for posting. It is very interesting to see the articles in Team-bhp.

How deep is that borewell and what was the cost?

On another note, is it possible to install a hand pump on (existing) borewells that are rather deep like 300ft?

Thank you for the kind words. The borewell is 350 feet deep. Good source of water is at 200 feet deep. So we have placed the pump at 250 feet. It cost about 40K to drill the borewell. I am not sure about the hand operated pumps.

Originally Posted by ninjatalli

- why not have more height to the stilts holding up the solar panels?...

- is the location of the solar panels (seems to be closer to your land's boundary further away from the house) more aligned to the water pump setup? Or say where the water levels are relatively higher? If not, wouldn't setting it up closer to the house avoided the cost for the poles to be setup?

- How come there are no trees/shrubs between the panels and the house? Not the part of land that you have irrigated yet? Or rather seems like a (future) grass/garden area

Happy to see this coming up nicely bit by bit

Thank you for the kind words Ninja!

1. Initially I thought of raising the height of the panels and park the car below. But then, cleaning would become very difficult. Even at this height, it is a little difficult to reach the middle panels on the top row. Gives a good workout in terms of strength and mobility. Another downside to raised solar was the structure would have costed at least 4x what it cost for this. This is because we will have to remove the center support to be able to utilise the space below. This would mean thicker supports at the corners and cross beams.

2. The location of the solar panels is chosen such that they are near the control room where all the electricity controls are located. In the future irrigation automation setup will also be installed in this room.

3. I have not yet planted anything there. I have dug up pits and fixed drip irrigation pipes to plant trees in this area and will do it mid May just before monsoon.

Originally Posted by libranof1987

Terrific stuff, graaja. This should help several people, given the rising popularity of both solar adoption, and farm/weekend homes.

1) How consistent do you anticipate the solar power generation to be through the year - will it generate enough to last your needs through winter/monsoon?

2) Will the power generated last your needs - home appliances, water motors and so on. Esp. with possible fluctuation in generation.

3) Someone has mentioned on another thread that efficiency drops as dirt/debris accumulate on the panels. Do you plan for an automated washing solution? Luckily your panels are easily accessible so manual cleaning should be easy - but not when you're away for extended period of time.

4) Noob question but how is excess generation handled since you can't send it to a grid? I'm assuming generation may be >> consumption + battery storage. Or would the circuit cut-off?

Thank you so much for the kind words!

1 & 2. For my usage, I expect the generation to be adequate the whole of the year. In the house, the loads including fridge would consume about 1.5kWH a day. The battery has a capacity to store 7.2kWh which can cover 4 days of usage easily. The system can charge the batteries to full capacity in 5 hours with just 1.6kW of power which is 50% of the panel capacity. In cloudy days, even if the panels produce 25% of power, there should be enough generation to cover the regular loads. I have not considered AC in the above calculations as we would be using AC only during day time on peak summer days. Other days, it is quite cool and we don't need an AC.

3. Yes. Efficiency drops if the panels get dirty. But even with a layer of dust, it still would produce 60 to 70% capacity which is more than adequate for my usage. I will be cleaning the panels manually whenever required.

4. Excess generation will be unused. Once the batteries are fully charged, any generation above the demand will be unused. Exporting the excess has two problems. The first is the cost to bring the grid. I need to install 6 to 7 posts which would cost around 2 lakhs. The second issue is the electricity board pays (this too on paper only) only 2.5 INR per unit of energy exported. So it is not economical to export the excess in my situation.

Originally Posted by skumare

Very well done, I guess the service providers also deserve accolades for such a professional installation.

I am evaluating options to install a solar system along with 7.5HP open well motor in a farm well, focussing on if we could go for a DC motor rather than the normal 3 phase AC one. Did you evaluate the option of a DC motor? Pls share your thoughts.

Thank you for the kind words. Yes. The installer did a fantastic job in terms of installation quality and finish. I did consider BLDC pumps. BLDC pumps have a very high efficiency. As there were very few options for BLDC models and as it was still in the early stage which may result in failures, I decided to go with the tried and tested setup. In may case a failure in the pump would require the pump to be lifted 250 feet out of the borewell which is a big hassle. But if you are planning for an open well setup where the pump is easily accessible, then you can definitely consider a BLDC. With its high efficiency, you may be able to do with a smaller solar array.

Originally Posted by chinkara

I was told by a solar engineering company in Indonesia I did some work for that the higher the frame height the more the chance of storm damage and accordingly the thickness of frames etc. So cost increases exponentially.

You are right. The cost of structure would be 3x to 4x compared to the low lying structure due to the increased thickness. Also cleaning would become very difficult.

Originally Posted by naveen.raju

Couple of things - It's an extra expense (ours is around 15 feet high) and hard to clean the panel during maintenance. We installed 3-4 years back and the guys did find it difficult to clean them.

You got a nice setup there. How do you manage to clean the panels? Do you use a ladder and a hose?

[psathya]

Excellent all around from idea to execution.... All the best to you.. I run a retirement community and the LPG prices are killing us.. Am trying to work out a combination of solar panels, boiler and pressure based cooking... will follow this thread

[naveen.raju]

Originally Posted by graaja

You got a nice setup there. How do you manage to clean the panels? Do you use a ladder and a hose?

Wife's workers does the cleaning. Too high for my liking . Bought an industrial size ladder and since we have a terrace garden, have a dedicated water supply.

But yes, it's a bit difficult but worth because we have a huge room in the middle of the garden.