Solar Powered GrowBox Concept

[SearchingforAnswers]

I am a student studying design and innovation and am working on a concept for a solar powered growbox using transparent/semi transparent photovoltaic glass. This type of pv glass does not currently generate as much electricity as the opaque monocrystalline polycrystalline panels we are more familar with but I believe it should generate enough energy to power a couple of a LED grow lamps for a few hours. I am trying to work out the electrical configuration and the components that I would need for my concept to be viable. Can anyone give any pointers on whether the proposed wiring diagram would work in practice. (Will this work without an inverter?). Any thoughts you can give me on my proposed design would be very much appreciated.


Here are some pictures of the growbox design. I intend to house the Battery and an MPPT Charge Controler in one of the compartments at the side of the product (the other compartments will be used for water storage for irrigation and the back of the growbox is for composting which will also help to generate an amount of heat in the colder months).

I would also love to hear your thoughts on any safety factors you think I will need to cover in the electrical design for the PV components.


Thanks for taking the time to respond your feedback will be very much appreciated.

 

[VermontOwl]

I like the concept.

Are the panels that appear, for lack of a better term, like “windows”, actually the solar panels?

Where will wiring run safely without being exposed to excessive moisture or pinch points at the frame/hinges?

 

[SearchingforAnswers]

I like the concept.

Are the panels that appear, for lack of a better term, like “windows”, actually the solar panels?

Where will wiring run safely without being exposed to excessive moisture or pinch points at the frame/hinges?

Thanks VermontOwl, you are correct the windows are infact the solar panels - (there have been trials on some greenhouses here in the UK - the glass is not yet fully transparent but allows enough light (approximately 50%) to filter through so that you can still grow plants beneath them) - at the moment the technology is not as efficient as the products currently being produced but it seems to be evolving rapidly so as you can imagine there is scope in the future for lots of exciting developments. (Maybe one day we will be able to replace all the glass in our homes with this type of PV glass and can stop relying so much on greedy energy companies!! One day...)

I have been thinking about some kind of external flexible conduit to protect the cables but not sure exactly how this will work in practice as it will be subjected to movement every time the frame is lifted open. I guess there will need to be enough slack in the cable to allow for this movement. I will take a look at what the options might be - thank you for your thoughts.

 

[OffGridForGood]

I think you are perhaps moving to the advanced tech at a high cost to the design efficiency:
Your project has a good sized roof 'wasted area' that could be standard solar panels, albeit not fancy new tech transparent ones.
The glass area could just be glass.
I know it is not as glamorous of a solution, but it uses all the areas more effectively, and relies on lower cost commonly available products.

 

[SamDeleted]

So let me get this straight....


You're blocking out 50% of the sun, in order to gather the other 50% , then you're going to use the sun you blocked out to give light to the plants .....

Am I missing something

Wouldn't it be better to just let the sun grow the plants ?

 

[SearchingforAnswers]

Thank you OffGridForGood, I am currently looking at how much the product would cost to produce so this will be good to compare as a standard solar panel would certainly be more efficient - definately something to explore as I look at the product's viability. My focus initially has been on innovation and how I might utilise new technology - I have been inspired by the potential for the future but right now I would probably have to agree with your comments. Still very useful feedback for my project so thanks for taking the time to comment.

 

[SamDeleted]

I mean it does looks pretty, I like the design


One of the problem is those solar glass panels are at best 10% efficient, almost certainly less than that


So you're blocking out 50% of your sun light , inorder to turn 10% into electricity, and then using that power to light the plants .

Then you add in the battery charge efficiency , inverter efficiency, LED driver efficiency, ,

Is this really going to work ?

 

[SamDeleted]

If you can get this to work mate , next project - perpetual motion machine

 

[SearchingforAnswers]

So let me get this straight....


You're blocking out 50% of the sun, in order to gather the other 50% , then you're going to use the sun you blocked out to give light to the plants .....

Am I missing something

Wouldn't it be better to just let the sun grow the plants ?

Thanks SamG340, from research currently underway it seems that plants can grow under the panels with the light that filters through (even though the panels are not yet fully transparent). https://www.theguardian.com/environ...-trial-wimbledon-berries-kent-hugh-lowe-farms. I was looking at the growlights as a means of providing a few addtional hours of light early in the season when our daylight hours are shorter - with a view to giving plants an earlier start in the year.

 

[Rednecktek]

So you're trying to play with agrovoltaics? Nice idea, but as pointed out the loss of light + lower efficiency is really going to hurt so you're going to need very shade tolerant plants that can deal with that. If you have the access to the correct panels though it might be worth playing with if nothing more than for the experience. I would suggest getting some normal panels on top of those compost bins to supplement the semi-transparent panels and put the two sets on different MPPT controllers so you can track how much power is generated from the normal panels VS the semi's, that's going to be useful information going forward, especially as you try to scale up.

Adding an exhaust fan, even just a small 120mm IP rated fan, to the battery box will help prevent excess condensation and should keep the electronics happy in the battery box. Everything in your wiring diagram looks good to go, you'll need to calculate the wattage for the lights and do the math on battery size but I see no problems. The heat from the compost bin certainly isn't going to hurt.

 

[SamDeleted]

Thanks SamG340, from research currently underway it seems that plants can grow under the panels with the light that filters through (even though the panels are not yet fully transparent). https://www.theguardian.com/environ...-trial-wimbledon-berries-kent-hugh-lowe-farms. I was looking at the growlights as a means of providing a few addtional hours of light early in the season when our daylight hours are shorter - with a view to giving plants an earlier start in the year.

In that article the solar panels are only mounted on the sides of the green house , not the roof ,

the vast majority of the sun light in those commercial greenhouses comes through the roof.





but yes makes a little bit more sense if you're trying to extend the growing season,,

But again trouble is, the bonus growth from the extra light hours in winter will be wiped out completely by cutting their daytime sun-light in half


In the UK in summer plants MIGHT well just grow ok a 50% light levels , certainly not great

In the winter, if you cut the light by half, your plants won't grow at all.

 

[SearchingforAnswers]

I mean it does looks pretty, I like the design


One of the problem is those solar glass panels are at best 10% efficient, almost certainly less than that


So you're blocking out 50% of your sun light , inorder to turn 10% into electricity, and then using that power to light the plants .

Then you add in the battery charge efficiency , inverter efficiency, LED driver efficiency, ,

Is this really going to work ?

I guess that's what I'm trying to work out. Even though the transparent panels are not so efficient I think that a single panel (Polysolar 64w Photovoltaic panel PS-CT Series - 1200x600mm) will generate enough power for an LED grow light for around 4 hours. As OffGridforGood has pointed out it would not be as efficient as using more standard solar panels currently avilable, however I think it is technically viable (though my calculations are limited by my electrical knowledge). Hence my post.

 

[Rednecktek]

I guess that's what I'm trying to work out. Even though the transparent panels are not so efficient I think that a single panel (Polysolar 64w Photovoltaic panel PS-CT Series - 1200x600mm) will generate enough power for an LED grow light for around 4 hours. As OffGridforGood has pointed out it would not be as efficient as using more standard solar panels currently avilable, however I think it is technically viable (though my calculations are limited by my electrical knowledge). Hence my post.

So they're 6w lights each? At 1200x600 for a 60w panel you're going to NEED additional panels involved as you'll only ever see that 60w in perfect conditions. UK weather is going to have a hard enough time getting up to charging voltage much of the year as it is, much less actually pulling anything useful out of them. It would be interesting to see how much power you can harvest out of that setup, but I would not rely on it to keep up the system.

As a reference, out where I live (Seattle, WA area) I had some solar driveway lights. They were drawing 120Wh a day in winter and I had 300w of solar panel on that system. I couldn't keep the battery charged through 4 months a year, there was just too much cloud cover to ever produce everything the lights had taken the night before. Every 6 weeks or so I'd have to pack the Jackery down to the bottom of the driveway and recharge the battery so it would go another 6 weeks.

Go for the experiment by all means, but don't count on those panels to produce enough to keep your batteries topped up for very long.

 

[SamDeleted]

So they're 6w lights each

They look like 100w to me

 

[Rednecktek]

They look like 100w to me

100w LED's?? OW MY EYES!! The ISS called! ?

 

[squowse]

So let me get this straight....


You're blocking out 50% of the sun, in order to gather the other 50% , then you're going to use the sun you blocked out to give light to the plants .....

Am I missing something

Wouldn't it be better to just let the sun grow the plants ?

And it’ll be 20% max of the 50% thats stored. The rest will heat up the glass.

 

[SearchingforAnswers]

If you can get this to work mate , next project - perpetual motion machine

Thanks for the vote of confidence! ?

 

[SearchingforAnswers]

So you're trying to play with agrovoltaics? Nice idea, but as pointed out the loss of light + lower efficiency is really going to hurt so you're going to need very shade tolerant plants that can deal with that. If you have the access to the correct panels though it might be worth playing with if nothing more than for the experience. I would suggest getting some normal panels on top of those compost bins to supplement the semi-transparent panels and put the two sets on different MPPT controllers so you can track how much power is generated from the normal panels VS the semi's, that's going to be useful information going forward, especially as you try to scale up.

Adding an exhaust fan, even just a small 120mm IP rated fan, to the battery box will help prevent excess condensation and should keep the electronics happy in the battery box. Everything in your wiring diagram looks good to go, you'll need to calculate the wattage for the lights and do the math on battery size but I see no problems. The heat from the compost bin certainly isn't going to hurt.

 

[SamDeleted]

I think it is technically viable

No it's doesn't mate, I'm sorry but I've got to tell you straight , I don't mean any offence, it's just cause I'm from up north


It's a rubbish idea , doesn't make any sense what so ever

you're clearly a smart lad I can see by your designs you're switched on . But this crap lol

 

[SearchingforAnswers]

Thanks Rednecktek, appreciate the feedback. It gives me a steer on things I can do to improve the design even though the energy being generated is likely questionable. Really helpful for the report that I have to put together for my assignment. I am not sure yet whether I will have the opportunity to develop a prototype but it would certainly be an interesting experiment.