Free Greenhouse Ventilation Via Solar Panel

Greenhouse too hot in summer? Provide much-needed air movement by adding free greenhouse ventilation using computer power supply fans and a solar panel.

While automatic vent openers in your greenhouse roof can help, adding some kind of supplementary greenhouse ventilation will also help.

Running large fans can get very expensive, both in purchasing the equipment and then the electricity needed to power them.

You can however get free greenhouse ventilation by combining an inexpensive solar panel with surplus computer power supply fans.

And as a bonus you can also add a USB charging plug for your portable devices!

What you will need

The shopping list for this easy DIY greenhouse project is short. In fact other than the solar panel, most of the other supplies could be gotten for next to nothing, which makes this project especially appealing if you are trying to stay on a budget.

Here is the quick list of affiliate links from Amazon for easy shopping. More info after the list if you want to source your own parts locally.

• Solar Panel: Renogy 100 Watts 12 Volts Polycrystalline Solar Starter Kit
• Fans: Rosewill 120mm Case Fan 4-Pack
• USB charging plug (optional): USB Car Charger RAVPower 24W 4.8A Metal Dual Car Adapter
• Y-adapter (optional if installing a USB charging plug): TEZONG Y Splitter 1 to 2 SAE Power Automotive Extension Cable

Solar panel

This is the most important purchase. It is best to not cheap out too much on this, as cheap panels may not be that efficient or last a long time.

Amazon.com doesn’t have the exact same panel that I have and I always have regretted not getting a slightly larger panel, so I’ve picked out a 100 watt panel with good ratings that comes with the charge controller (if you add batteries later), cabling and even mounting brackets. Here is the link: Renogy 100 Watts 12 Volts Polycrystalline Solar Starter Kit

Fans

These fans serve to exhaust hot air out of a computer case and are 12 volt which is what the panel is. They are built to work in a dusty environment.

These might actually be sourced for free from a computer repair shop if you ask nicely. I got mine from discarded PCs at work.

But if you can’t locate them easily for free, they are also available online in a convenient 4-pack: Rosewill 120mm Case Fan 4-Pack

Charging plug (optional)

If you want to also charge your portable devices such as smartphones, tablets and music players, you can add a USB charging adapter such as you will find that plugs into your car’s 12 volt accessory port. I got mine for free once at a technology conference but you can also find them online. Here is a reasonably priced one that also has a handy indicator light to let you know when your panel is producing power: USB Car Charger RAVPower 24W 4.8A Metal Dual Car Adapter

And to make it easy to power both the USB charging plug and greenhouse fans from the same solar panel, ideally you need a Y-adapter: TEZONG Y Splitter 1 to 2 SAE Power Automotive Extension Cable

WARNING: don’t try and charge your devices directly from the solar panel – USB is 5 volts whereas the panel is 12 volts. The adapter above converts 12 volts down to 5 volts safely to avoid frying your expensive electronic devices.

Wire/Cable

Finally you might need to obtain some wire to hook up the panel to your greenhouse, especially if the panel is far away. For this use standard house cable (Romex is one brand name) as you won’t lose power due to resistance. I happened to have a piece left over from another project and it was long enough. You just need two conductors (wires bundled up) so if your cable has more, just ignore the extra ones. Pick this up at your local hardware store or home centre. You may be able to simply buy it by the foot so you get the right length without too much excess.

Installation

Your installation will likely be different from mine depending on what you are using and where you are installing it. So I’ll explain and show you what I did and then you can adjust to your specific situation.

Ju