Enough solar?

[Furbrain]

Greetings,

At some point I will try growing indoors but first will install solar to the house. I am well-known for doing things ass about face sometimes and have just purchased a Solar system. 5kw Inverter, 2.2kw Panel Capacity and 5kwh Lithium Battery.

I hope to run a grow inside a 2.4mtrx1.2mtr tent. Do you think I will have enough power to run LED lights, extractor fan etc for probably 10 hrs at least?

If your doing an 18hr on and 6 off grow and getting approx +/- 9 hrs sunlight (Winter grow) , that means I will need to run lights etc for at least 11hrs. Will the 5k lithium battery handle this?.

Cheers....

 

 

[Totemic]

I have for countering loadshedding purposes gone down this rabbit hole, and ultimately decided it would be too costly to keep my setup running for even those 2 hours using an inverter and 2 x 100ah deep cycle batteries. 

The problem isn't keeping the lights on, as Led lights dont draw that much current. 

It's the fans(anything with a motor) that draws power out of batteries Hella fast. 

So while the sun is out and blasting you should possibly be able to keep the environment running, but after dark you will need the grid to keep it going

Edited January 27, 2022 by Totemic

[Furbrain]

12 hours ago, Totemic said:

I have for countering loadshedding purposes gone down this rabbit hole, and ultimately decided it would be too costly to keep my setup running for even those 2 hours using an inverter and 2 x 100ah deep cycle batteries. 

The problem isn't keeping the lights on, as Led lights dont draw that much current. 

It's the fans(anything with a motor) that draws power out of batteries Hella fast. 

So while the sun is out and blasting you should possibly be able to keep the environment running, but after dark you will need the grid to keep it going

Thanks Totemic. I'm not surprised at your answer!.

Would you know roughly how much power a small setup would need?. I do get confused with how many Watts/Amps needed and how much Lithium batteries produce!. For instance, apparently the battery I'm getting has a usable capacity of 4560Wh!. So if a fan is rated at 60watts it will draw 60÷1000=  0.06wh......................I think?.

To be honest I don't seem to know how to work out the total power nessesary to run LED's, extractor fan, inlet fan etc.

Maybe someone could give me a rough idea how much power I actually need?.

Thanking you in advance.

Cheers.....

[SAgrower]

Thanks Totemic. I'm not surprised at your answer!.
Would you know roughly how much power a small setup would need?. I do get confused with how many Watts/Amps needed and how much Lithium batteries produce!. For instance, apparently the battery I'm getting has a usable capacity of 4560Wh!. So if a fan is rated at 60watts it will draw 60÷1000=  0.06wh......................I think?.
To be honest I don't seem to know how to work out the total power nessesary to run LED's, extractor fan, inlet fan etc.
Maybe someone could give me a rough idea how much power I actually need?.
Thanking you in advance.
Cheers.....

If you post the electricity usage of each piece of equipment and for how long they will run I could ask someone which setup would work best

[West Coast Vaper]

Try and get your hands on one of these. Got mine from @growopz .


240w QB set at 220w
2 x 75w QB
300w blurple which only draws 77w
3 x fans
Total Watt 516


This has helped a lot figuring out cost's.


Sent from my S40 using Tapatalk

[Furbrain]

28 minutes ago, DamDave said:

Try and get your hands on one of these. Got mine from @growopz .


240w QB set at 220w
2 x 75w QB
300w blurple which only draws 77w
3 x fans
Total Watt 516


This has helped a lot figuring out cost's.


Sent from my S40 using Tapatalk
 

Thanks Damdave.

My problem now is the maths!.

If my 5kw lithium battery has a storage capacity of 4500watts,............how long would that run your setup that uses 516watts?. At the risk of seeming thick...............would my battery power your setup for 9hrs?. (4500÷516=8.7).

No wonder my late Father (an Electrical engineer), was disappointed I couldn't grasp this whole amps Watts voltage thing!.

Cheers......

[Dookie69]

I have 2 x 200Ah deep cycle gel batteries on a 5kVa inverter (No solar panels yet). It just to keep running during load shedding or any other time a poorly maintained transformer blows up in my area. I have a 240w LED, a Dehumidifier and fans / extraction on the inverter. This will run for close to 5hrs tho Lithium would run longer since I understand they can go to a lower voltage without damage. Then I have a generator to charge the inverter if it comes to that.
Sustained high humidity is the killer if you are in a humid area so I focus on air movement and dehumidification.
I run autos so the light is less critical. My “emergency light” also forms part of my normal lights, so it runs on its own timer and comes on and off like the rest of them under normal circumstances.

[Furbrain]

3 minutes ago, Furbrain said:

Thanks Damdave.

My problem now is the maths!.

If my 5kw lithium battery has a storage capacity of 4500watts,............how long would that run your setup that uses 516watts?. At the risk of seeming thick...............would my battery power your setup for 9hrs?. (4500÷516=8.7).

No wonder my late Father (an Electrical engineer), was disappointed I couldn't grasp this whole amps Watts voltage thing!.

Cheers......

By the way,............. how large is your growing area please?.

I had intended to grow in 2.4x1.2x2.0mtr tent with 2 maybe 3  plants in 20ltr pots. Also wonder what hours your light schedule is for using 516watts?.

[Furbrain]

3 minutes ago, Dookie69 said:

I have 2 x 200Ah deep cycle gel batteries on a 5kVa inverter (No solar panels yet). It just to keep running during load shedding or any other time a poorly maintained transformer blows up in my area. I have a 240w LED, a Dehumidifier and fans / extraction on the inverter. This will run for close to 5hrs tho Lithium would run longer since I understand they can go to a lower voltage without damage. Then I have a generator to charge the inverter if it comes to that.
Sustained high humidity is the killer if you are in a humid area so I focus on air movement and dehumidification.
I run autos so the light is less critical. My “emergency light” also forms part of my normal lights, so it runs on its own timer and comes on and off like the rest of them under normal circumstances.

Thanks for that Dookie. My lithium battery is only 200ah!. It's 5kva with 4500w capacity.

I still can't get my head around what power is needed for a small setup and how long (hours) a fully charged battery would give me?. Damdave's 516watts has given me a baseline although I 'think' he is running a larger setup?.

I'm in the Klien Karroo so humidity is not so much of a concern.

[Furbrain]

1 hour ago, SAgrower said:

1 hour ago, Furbrain said:

Thanks Totemic. I'm not surprised at your answer!.
Would you know roughly how much power a small setup would need?. I do get confused with how many Watts/Amps needed and how much Lithium batteries produce!. For instance, apparently the battery I'm getting has a usable capacity of 4560Wh!. So if a fan is rated at 60watts it will draw 60÷1000=  0.06wh......................I think?.
To be honest I don't seem to know how to work out the total power nessesary to run LED's, extractor fan, inlet fan etc.
Maybe someone could give me a rough idea how much power I actually need?.
Thanking you in advance.
Cheers.....

If you post the electricity usage of each piece of equipment and for how long they will run I could ask someone which setup would work best

Good morning.

Fact is I'm not sure what equipment I will need to start with?. I intend using a 2.4x1.2mtr tent with possibly 2 or 3 plants in 20ltr pots.

What I need is advice on what equipment to use ie LED's , fans etc. Then we can understand what my power needs to be?. I'm sure there must be a base setup for my size grow!.

What lights, fans etc etc are suggested??????.

Appreciate your help.....

 

 

[Bos]

@Furbrain

Depending if its a 12v or 24v setup.

Battery capacities are a bit of an enigma, but usually you can only use 50% of your battery capacity. Obviously different types have slightly different specs. You can discharge your batteries to a lower state of charge eg:30% but you can also easily damage them.

This is a rough calculation, so feel free to add your 2c.

1.Add up all your power consumers watts W.

2.Devide the total watts by the voltage of your battery.

3.That gives you the

Amp draw on the system per hour.

W÷Volt= Amps

4. Devide 50% of your batteries' rated Ah by the Amps and the answer will tell you how long your system will run. (General rule of thumb, only discharge battery to 50% for safety)

200ah 12v battery with a 516watt setup.

516w/12v=43amp/hr

200ah/2=100amp/hr (use 50% for safety)

You have 100amp/hr capacity divided by a draw of 43amp/hr from the equipment.

100/43= 2.3hrs that the setup can run.

 

 

[West Coast Vaper]

By the way,............. how large is your growing area please?.
I had intended to grow in 2.4x1.2x2.0mtr tent with 2 maybe 3  plants in 20ltr pots. Also wonder what hours your light schedule is for using 516watts?.

I think your father would have given me a clip behind the ear if he saw my electrical experience.

I have just bought a larger than expected tent 2.4m x 1.2m x 2m.

Blurple will be in the old cabinet for vegging.
QB's in the tent for hopefully perpetual flowering. Or so that's the plan.

Blurple (77w) will run 24 hours until I get another timer.
QB's and fan's on for 12 hours.

When I had everything running for 18 hours a day our household electric bill was round 800 bucks, 1200 when the wife bakes a month.

Thinking 4 small pots under the 240w and 2 small pots under the 2 x 75w.

Then the odd 50 bucks here and there is already finding its way into the kitty for the next piece of equipment.








Sent from my S40 using Tapatalk

[Furbrain]

5 minutes ago, Bos said:

@Furbrain

Depending if its a 12v or 24v setup.

Battery capacities are a bit of an enigma, but usually you can only use 50% of your battery capacity. Obviously different types have slightly different specs. You can discharge your batteries to a lower state of charge eg:30% but you can also easily damage them.

This is a rough calculation, so feel free to add your 2c.

1.Add up all your power consumers watts W.

2.Devide the total watts by the voltage of your battery.

3.That gives you the

Amp draw on the system per hour.

W÷Volt= Amps

4. Devide 50% of your batteries' rated Ah by the Amps and the answer will tell you how long your system will run. (General rule of thumb, only discharge battery to 50% for safety)

200ah 12v battery with a 516watt setup.

516w/12v=43amp/hr

200ah/2=100amp/hr (use 50% for safety)

You have 100amp/hr capacity divided by a draw of 43amp/hr from the equipment.

100/43= 2.3hrs that the setup can run.

 

 

Hi Boss,

5kw Inverter, 2.2kw Panel Capacity and 5kwh Lithium Battery(200ah). Would the lithium battery give more running time than a 'normal' battery?.

[Furbrain]

3 minutes ago, Furbrain said:

Hi Boss,

5kw Inverter, 2.2kw Panel Capacity and 5kwh Lithium Battery(200ah). Would the lithium battery give more running time than a 'normal' battery?.

Sorry, forgot to mention it's a 48V system!.

[Bos]

The inverter and panels seem up to the job, but the battery capacity is a bit small. Lithium batteries are usually able to discharge to a lower SOC(state of charge) this is specific to the battery and you'll have to check with manufacturer.

That setup can only be run for 2hrs, if you require 18hrs.. you'll need 8x more batteries. Then you'll have to check if your solar panel is able to put back what you take out. Solar panel efficiency is another lot of black magic....  direct sunlight at 90deg angle is most effecient, but the sun moves and panels don't, so not 100% efficient most of the time. Any cloudy or rainy weather and the system won't recharge as fast as needed.

If you have no "reserve" built in (extra batteries and panels-above and beyond the 9xbatteries and 2.2kwh panel) on the first cloudy day you will run into problems.

[Furbrain]

17 minutes ago, Furbrain said:

Hi Boss,

5kw Inverter, 2.2kw Panel Capacity and 5kwh Lithium Battery(200ah). Would the lithium battery give more running time than a 'normal' battery?.

If I can use

[Bos]

12 minutes ago, Furbrain said:

Sorry, forgot to mention it's a 48V system!.

Based on a hypothetical grow using 516watts per hour.

Battery 100amp/hr available capacity.

516w÷48V = 10.75amps

100amp/hr ÷ 10.75amp= 9.3hr run time

If you run the fans during lights off you need to factor that in.

On 18/6 schedule you would need minimum 2x batteries and then still it will be touch and go reliability wise. But you need to build surplus into the system otherwise you cant upgrade or add anything to the grow as you'll affect the battery capacity. You'll need 3 or 4 batteries based on this example.

[Furbrain]

2 minutes ago, Bos said:

The inverter and panels seem up to the job, but the battery capacity is a bit small. Lithium batteries are usually able to discharge to a lower SOC(state of charge) this is specific to the battery and you'll have to check with manufacturer.

That setup can only be run for 2hrs, if you require 18hrs.. you'll need 8x more batteries. Then you'll have to check if your solar panel is able to put back what you take out. Solar panel efficiency is another lot of black magic....  direct sunlight at 90deg angle is most effecient, but the sun moves and panels don't, so not 100% efficient most of the time. Any cloudy or rainy weather and the system won't recharge as fast as needed.

If you have no "reserve" built in (extra batteries and panels-above and beyond the 9xbatteries and 2.2kwh panel) on the first cloudy day you will run into problems.

The system is 48V. If I can draw 'most' of the 200amps(lithium) and the grow system uses say 500w,......then ; 500÷48= 10.4Amps????.

I don't think I am correct here!.

[Bos]

2 minutes ago, Furbrain said:

The system is 48V. If I can draw 'most' of the 200amps(lithium) and the grow system uses say 500w,......then ; 500÷48= 10.4Amps????.

I don't think I am correct here!.

You'd need to find out from the batt manufacturer what the specs are on safe discharge limits.

516w÷48v=10.75amps

In a perfect world, hypothetically.

200amp/hr÷10.75amps=18.6hr

There are losses in these systems so it will not work this perfectly. Resistance and heat loss in the batteries,inverter and cables hence the need for extra capacity.

FYI.....With all due respect to ANY diy grower looking at this type of setup/idea.....Please dont mess with DC power unless you know EXACTLY what you are doing. Otherwise get a qualified installer.

DC can and will kill you.

[West Coast Vaper]

You'd need to find out from the batt manufacturer what the specs are on safe discharge limits.
516w÷48v=10.75amps
In a perfect world, hypothetically.
200amp/hr÷10.75amps=18.6hr
There are losses in these systems so it will not work this perfectly. Resistance and heat loss in the batteries,inverter and cables hence the need for extra capacity.
FYI.....With all due respect to ANY diy grower looking at this type of setup/idea.....Please dont mess with DC power unless you know EXACTLY what you are doing. Otherwise get a qualified installer.
DC can and will kill you.

Take note on DC will kill you.
So many people started growing out here and besides the shock factor farms have been razed to the ground because of dodgy electrics.
The police did a sort of blitz in the area knocking on doors looking for grow set-ups purely to check for safe wiring.


Sent from my S40 using Tapatalk

[Furbrain]

1 hour ago, Bos said:

You'd need to find out from the batt manufacturer what the specs are on safe discharge limits.

516w÷48v=10.75amps

In a perfect world, hypothetically.

200amp/hr÷10.75amps=18.6hr

There are losses in these systems so it will not work this perfectly. Resistance and heat loss in the batteries,inverter and cables hence the need for extra capacity.

FYI.....With all due respect to ANY diy grower looking at this type of setup/idea.....Please dont mess with DC power unless you know EXACTLY what you are doing. Otherwise get a qualified installer.

DC can and will kill you.

Hi Boss,

I've spoken with my supplier and he assures me that my system will power my basics, fridge etc for many hours. He knows about my intention for indoor growing and suggests trying the system first before making plans to double the number of panels and installing another 5kv battery. He suggests that the one battery will give me approx 4600watts.

It's fairly obvious that I will probably end up enlarging this system for an indoor grow but let's see how stage 1 works out first.

I've bought from a reputable dealer and price includes a professional electrician to wire up and commission the system. Even get a COC!.

No way I touch any electrics.......DC or AC!. Can't see any of those pesky and dangerous electrons so I've always left well alone!.

Thanks for your input and have a lekker weekend.

 

46 minutes ago, DamDave said:

Take note on DC will kill you.
So many people started growing out here and besides the shock factor farms have been razed to the ground because of dodgy electrics.
The police did a sort of blitz in the area knocking on doors looking for grow set-ups purely to check for safe wiring.


Sent from my S40 using Tapatalk
 

 

[Furbrain]

Just now, Furbrain said:

Hi Boss,

I've spoken with my supplier and he assures me that my system will power my basics, fridge etc for many hours. He knows about my intention for indoor growing and suggests trying the system first before making plans to double the number of panels and installing another 5kv battery. He suggests that the one battery will give me approx 4600watts.

It's fairly obvious that I will probably end up enlarging this system for an indoor grow but let's see how stage 1 works out first.

I've bought from a reputable dealer and price includes a professional electrician to wire up and commission the system. Even get a COC!.

No way I touch any electrics.......DC or AC!. Can't see any of those pesky and dangerous electrons so I've always left well alone!.

Thanks for your input and have a lekker weekend.

 

 

 

1 minute ago, Furbrain said:

Hi Boss,

I've spoken with my supplier and he assures me that my system will power my basics, fridge etc for many hours. He knows about my intention for indoor growing and suggests trying the system first before making plans to double the number of panels and installing another 5kv battery. He suggests that the one battery will give me approx 4600watts.

It's fairly obvious that I will probably end up enlarging this system for an indoor grow but let's see how stage 1 works out first.

I've bought from a reputable dealer and price includes a professional electrician to wire up and commission the system. Even get a COC!.

No way I touch any electrics.......DC or AC!. Can't see any of those pesky and dangerous electrons so I've always left well alone!.

Thanks for your input and have a lekker weekend.

 

 

 

2 minutes ago, Furbrain said:

Hi Boss,

I've spoken with my supplier and he assures me that my system will power my basics, fridge etc for many hours. He knows about my intention for indoor growing and suggests trying the system first before making plans to double the number of panels and installing another 5kv battery. He suggests that the one battery will give me approx 4600watts.

It's fairly obvious that I will probably end up enlarging this system for an indoor grow but let's see how stage 1 works out first.

I've bought from a reputable dealer and price includes a professional electrician to wire up and commission the system. Even get a COC!.

No way I touch any electrics.......DC or AC!. Can't see any of those pesky and dangerous electrons so I've always left well alone!.

Thanks for your input and have a lekker weekend.

 

 

Yep,...........right on the mark. The things that go on here in SA!.

Thanks Dave, I will have professional to fit the system!.

Please see my post to Boss.

Lekker weekend to you.

[PsyCLown]

A bit of a TLDR, so did not read every post but will try answer all questions.

 

I have looked into a solar setup myself and have had friends who have gone ahead with solar setups - if you use a lot of power it makes sense to go this route.

 

Firstly, 5KW inverter with 2.2KW of panels is silly, you generally want to try and aim for more panels than the inverter is rated for as the panels efficiency will decrease with time and are the limiting factor as to how much power you can pull from the sun. The weather varies, some days there will be more cloud coverage and power production starts when the sun rises but you won't be generating max power early in the morning or late in the afternoon when the sun starts to set - this is where the additional panels will start to shine and help you maximize how much power you are able to produce throughout the light cycle of the day - as you seem to be aware, winter things change as well and there are less hours of light.

So without a doubt, look at adding more panels. Especially if you want to run the whole house and subsidise the grow when the sun is shining.

Also make sure that 5KW is sufficient for your house, draw too much and the inverter will trip - your whole house is then without power until you turn it on again. Geyser, kettle, stove, grow lights, fans, aircon, dishwasher, washing machine, tumble dryer TV etc. etc. It can all add up quickly

You may need to change your habits in terms of how you use electricity and what appliances you have on at the same time in order to make the 5KW inverter work. This is something only you'd be able to work out as you know what appliances you use and when you use them.

 

 

Now onto the question of your grow equipment and the draw and the battery.

Let's start with the grow equipment, for a 1.2m x 2.4m tent you'd like to aim for 4x 240W Quantum Boards which comes to just under 1KW of power (let's round up to 1KW take the efficiency of the driver into account).

You will need to have fans to circulate the air, as well as for extraction and possibly intake as well. 100W to 200W is a reasonable estimation, we'll go with 200W to be on the safe side.

Now depending on your grow, there may be additional equipment such as water pumps for automatic watering (often not a high amount of power), aircon, dehumidifier - these need to be taken into account if you are running them.

However we can consider a base load of 1.2KW when your tent is running at full power with all fans. So that means 1.2KW (1200W) which is being drawn by your tent per hour. 1.2KWH in other words or 1.2 units per hour. During veg you can dim the lights down to around 400w in the tent and should be fine, in flower you will be pushing the full 1KW of power to the lights if you have the tent full of plants.

 

So for veg, 600W per hour with fans.

For flower, 1200W per hour with fans.

When lights are off, 200W per hour for just the fans.

 

Lithium battery is 100% the way you want to go, they generally come with a 10 year+ warranty and are able to be discharged more than your typical gel / deep cycle batteries. What is meant by discharge (also known as depth of discharge), well, the 5KW battery is basically a 105ah battery at 48v (105ah x 48v = 5040W (5KW) ). We can use the 5000W figure here to explain DoD (Depth of Discharge):

A 10% DoD means the battery has been drained by 10%. So 5000 - 10% = 4500W of charge remaining in the battery. 50% DoD = 2500W remaining in the battery. 80% DoD = 1000W of power remaining in the battery.

Your typical AGM / deep cycle batteries can be discharged to around 50% at most and even then they have far fewer cycles which they can handle (a decent deep cycle AGM type battery can handle around 600 cycles).

A Lithium battery can be discharged past 50% safely, unlike your AGM / gel / deep cycle type of batteries which can take serious, permanent damage if discharged past 50%. Most Lithium batteries for solar use are able to be safely discharged to anywhere from 85% to 100% - keeping in mind that the further you discharge it, the fewer cycles you will get.

As an example, a Lithium battery may be good for 6000 cycles at 80% DoD but only 3500 cycles at 100% DoD. These are rather accurate figures for Lithium batteries as well, I think Hubble and/or Pylontech batteries offer figures similar to the above. As you can see, 6000 cycles is 10 times more usage out of the Lithium battery compared to an AGM style battery with 600 cycles. Also you are able to get 80% discharge out of the Lithium battery (4000W) compared to 50% discharge out of the AGM battery (2500W).

Another figure to briefly touch on is the constant discharge rate, not all batteries are able to safely provide the required current for an extended period of time. So you may require multiple AGM batteries in order to safely allow the 5KW inverter to draw 5KW of power from the batteries.

You get Lithium batteries where a single battery is able to provide sufficient power to max out a 5KW inverter - one thing to keep in mind when looking at buying batteries for your inverter (or a single battery).

 

So now to the final part of your question, how long will the battery be able to run your grow setup for. Well, I have done the basic maths already so we know that with lights during veg you are drawing 600W of power roughly (per hour) and the battery has a total capacity of 5000W (let's say you want to only discharge to 80% to help prolong battery life, or to keep some power spare incase of load shedding / emergencies). That leaves us with 4000W of power to draw from the battery.

4000W / 600W = 6.66 hours (Around 6 hours and 38 minutes I think)

 

In flower, a very different story. Literally half as the draw is 1200W.

4000W / 1200W = 3.33 hours (Around 3 hours and 23 minutes I think)

 

The above calculations do not take into account whatever else is running and drawing power in the house. If your geyser turns on and it is a 3KW geyser, that is 3000W it can use within an hour and will almost drain the battery quickly, almost to the full 80% DoD within an hour.

Fridges & freezers cycles on and off multiple times throughout the day, there will often be basics running such as the fridge / freezer, some lights, router for internet etc. These are often small amounts of power being drawn but it is still there and needs to be taken into consideration.

 

The biggest benefit with solar is being able to run off the panels during the day when the sun is shining and this is where the biggest cost savings will come in. The battery is nice to have, but running a grow off batteries for an extended period of time is stupidly expensive for initial costs (around R25k for a 100ah Lithium battery). When the sun goes down, it makes more sense to switch over to Eskom's grid and keep the battery for load shedding or emergency use and during the day when there is a bit of cloud coverage.

 

If you need to be off grid, the cheaper way would be to have a generator tied to the inverter as opposed to buying multiple batteries. However when it comes to running costs - over a long enough period of time the generator may work out more expensive and it has it's drawbacks too - requires fuel, isn't good for the environment with the emissions, require services & maintenance and it is noisy. However the initial cost of a generator is far cheaper than multiple batteries.

[Furbrain]

1 hour ago, PsyCLown said:

A bit of a TLDR, so did not read every post but will try answer all questions.

 

I have looked into a solar setup myself and have had friends who have gone ahead with solar setups - if you use a lot of power it makes sense to go this route.

 

Firstly, 5KW inverter with 2.2KW of panels is silly, you generally want to try and aim for more panels than the inverter is rated for as the panels efficiency will decrease with time and are the limiting factor as to how much power you can pull from the sun. The weather varies, some days there will be more cloud coverage and power production starts when the sun rises but you won't be generating max power early in the morning or late in the afternoon when the sun starts to set - this is where the additional panels will start to shine and help you maximize how much power you are able to produce throughout the light cycle of the day - as you seem to be aware, winter things change as well and there are less hours of light.

So without a doubt, look at adding more panels. Especially if you want to run the whole house and subsidise the grow when the sun is shining.

Also make sure that 5KW is sufficient for your house, draw too much and the inverter will trip - your whole house is then without power until you turn it on again. Geyser, kettle, stove, grow lights, fans, aircon, dishwasher, washing machine, tumble dryer TV etc. etc. It can all add up quickly

You may need to change your habits in terms of how you use electricity and what appliances you have on at the same time in order to make the 5KW inverter work. This is something only you'd be able to work out as you know what appliances you use and when you use them.

 

 

Now onto the question of your grow equipment and the draw and the battery.

Let's start with the grow equipment, for a 1.2m x 2.4m tent you'd like to aim for 4x 240W Quantum Boards which comes to just under 1KW of power (let's round up to 1KW take the efficiency of the driver into account).

You will need to have fans to circulate the air, as well as for extraction and possibly intake as well. 100W to 200W is a reasonable estimation, we'll go with 200W to be on the safe side.

Now depending on your grow, there may be additional equipment such as water pumps for automatic watering (often not a high amount of power), aircon, dehumidifier - these need to be taken into account if you are running them.

However we can consider a base load of 1.2KW when your tent is running at full power with all fans. So that means 1.2KW (1200W) which is being drawn by your tent per hour. 1.2KWH in other words or 1.2 units per hour. During veg you can dim the lights down to around 400w in the tent and should be fine, in flower you will be pushing the full 1KW of power to the lights if you have the tent full of plants.

 

So for veg, 600W per hour with fans.

For flower, 1200W per hour with fans.

When lights are off, 200W per hour for just the fans.

 

Lithium battery is 100% the way you want to go, they generally come with a 10 year+ warranty and are able to be discharged more than your typical gel / deep cycle batteries. What is meant by discharge (also known as depth of discharge), well, the 5KW battery is basically a 105ah battery at 48v (105ah x 48v = 5040W (5KW) ). We can use the 5000W figure here to explain DoD (Depth of Discharge):

A 10% DoD means the battery has been drained by 10%. So 5000 - 10% = 4500W of charge remaining in the battery. 50% DoD = 2500W remaining in the battery. 80% DoD = 1000W of power remaining in the battery.

Your typical AGM / deep cycle batteries can be discharged to around 50% at most and even then they have far fewer cycles which they can handle (a decent deep cycle AGM type battery can handle around 600 cycles).

A Lithium battery can be discharged past 50% safely, unlike your AGM / gel / deep cycle type of batteries which can take serious, permanent damage if discharged past 50%. Most Lithium batteries for solar use are able to be safely discharged to anywhere from 85% to 100% - keeping in mind that the further you discharge it, the fewer cycles you will get.

As an example, a Lithium battery may be good for 6000 cycles at 80% DoD but only 3500 cycles at 100% DoD. These are rather accurate figures for Lithium batteries as well, I think Hubble and/or Pylontech batteries offer figures similar to the above. As you can see, 6000 cycles is 10 times more usage out of the Lithium battery compared to an AGM style battery with 600 cycles. Also you are able to get 80% discharge out of the Lithium battery (4000W) compared to 50% discharge out of the AGM battery (2500W).

Another figure to briefly touch on is the constant discharge rate, not all batteries are able to safely provide the required current for an extended period of time. So you may require multiple AGM batteries in order to safely allow the 5KW inverter to draw 5KW of power from the batteries.

You get Lithium batteries where a single battery is able to provide sufficient power to max out a 5KW inverter - one thing to keep in mind when looking at buying batteries for your inverter (or a single battery).

 

So now to the final part of your question, how long will the battery be able to run your grow setup for. Well, I have done the basic maths already so we know that with lights during veg you are drawing 600W of power roughly (per hour) and the battery has a total capacity of 5000W (let's say you want to only discharge to 80% to help prolong battery life, or to keep some power spare incase of load shedding / emergencies). That leaves us with 4000W of power to draw from the battery.

4000W / 600W = 6.66 hours (Around 6 hours and 38 minutes I think)

 

In flower, a very different story. Literally half as the draw is 1200W.

4000W / 1200W = 3.33 hours (Around 3 hours and 23 minutes I think)

 

The above calculations do not take into account whatever else is running and drawing power in the house. If your geyser turns on and it is a 3KW geyser, that is 3000W it can use within an hour and will almost drain the battery quickly, almost to the full 80% DoD within an hour.

Fridges & freezers cycles on and off multiple times throughout the day, there will often be basics running such as the fridge / freezer, some lights, router for internet etc. These are often small amounts of power being drawn but it is still there and needs to be taken into consideration.

 

The biggest benefit with solar is being able to run off the panels during the day when the sun is shining and this is where the biggest cost savings will come in. The battery is nice to have, but running a grow off batteries for an extended period of time is stupidly expensive for initial costs (around R25k for a 100ah Lithium battery). When the sun goes down, it makes more sense to switch over to Eskom's grid and keep the battery for load shedding or emergency use and during the day when there is a bit of cloud coverage.

 

If you need to be off grid, the cheaper way would be to have a generator tied to the inverter as opposed to buying multiple batteries. However when it comes to running costs - over a long enough period of time the generator may work out more expensive and it has it's drawbacks too - requires fuel, isn't good for the environment with the emissions, require services & maintenance and it is noisy. However the initial cost of a generator is far cheaper than multiple batteries.

Dear Psyclown,

Thankyou so much!. 10 out of 10 for that answer!.

I feel fully clued up know.

Trouble is.......I do get a bit carried away at times. I lived in Spain for a few years and had absolutely no electricity up in the hills. My solar system worked like a dream. I only grew outside, so didn't need too much power. However, the system handled a pool pump for 7 hrs every day , the household water had pumps also.

That was 5 years ago. Wow .......solar has moved on from then!.

Anyhow, turns out I'll need a lot more power than my old 6 panel system! (Photo).

At least now I know what I'm dealing with and what I need to make things work.

I'm going ahead with my intended system in the knowledge that I can add extra panels and battery later.

I've come to peace with the fact that it will cost me a lot more than I had previously thought!. Just have to wait to get the funds together that's all. Patience is the key.

One other thought; What if I scaled it right down to single tent with one plant?. One reasonable plant?. But then I suppose you still have to have the same gear, fans etc.

Ah well, my dream of giving Eskom the finger alludes me for now.

Thanks again for your valuable insight.

Have a lekker weekend. PS, Photos will be sent separately as they are on my pc.

 

[PsyCLown]

Dear Psyclown,
Thankyou so much!. 10 out of 10 for that answer!.
I feel fully clued up know.
Trouble is.......I do get a bit carried away at times. I lived in Spain for a few years and had absolutely no electricity up in the hills. My solar system worked like a dream. I only grew outside, so didn't need too much power. However, the system handled a pool pump for 7 hrs every day , the household water had pumps also.
That was 5 years ago. Wow .......solar has moved on from then!.
Anyhow, turns out I'll need a lot more power than my old 6 panel system! (Photo).
At least now I know what I'm dealing with and what I need to make things work.
I'm going ahead with my intended system in the knowledge that I can add extra panels and battery later.
I've come to peace with the fact that it will cost me a lot more than I had previously thought!. Just have to wait to get the funds together that's all. Patience is the key.
One other thought; What if I scaled it right down to single tent with one plant?. One reasonable plant?. But then I suppose you still have to have the same gear, fans etc.
Ah well, my dream of giving Eskom the finger alludes me for now.
Thanks again for your valuable insight.
Have a lekker weekend. PS, Photos will be sent separately as they are on my pc.
 

So regarding 6 panels and adding more later, remember that the string of panels ideally needs to be in a certain voltage range - too low and efficiency drops, too high and it'll cause permanent damage to the inverter.

If the amps (current) is too high per string / mppt the. That'll just get cut and limited.
Also remember you need to take into account the temperatures as that'll affect the voltage, cold weather will lead to higher voltage. So you need to work it out to be in a safe zone.



As for going down to a small tent of say 80x80
Putting a small light of no more than 240w inside, will definitely reduce the power required. Smaller tent, means less lights and smaller fans and therefore less power.

If running the light at max during flower, fans may come to approx 60w so call it 300w in total at max.
In veg it'll be less power and you could get away with just an extraction fan and one fan inside for air circulation.

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