Building your own plant lamps - DIY Grow LED - continues to be the trend. Why are do-it-yourself LEDs so attractive for plant lighting in private indoor cultivation? When it comes to lighting for plants, there are three central requirements that have long been contradictory:
- Low acquisition costs, as many photons per Euro as possible
- An even distribution of light over the entire cultivation area. This means the most homogeneous PPFD values.
- Efficiency. As many photons as possible per kilowatt hour of electrical energy.
High intensity discharge lamps - NDL/HPS & Co.
Until a few years ago, the most popular light sources for indoor plant lighting were gas discharge lamps (NDL, MDL, etc.), as they promised a high light yield at low investment costs.
But even if we ignore the heat problem of this type of lamp, there is a big problem with the even distribution of light. Reflectors and spreaders can only avoid so-called hotspots at the expense of efficiency, while the illumination at the edges is greatly reduced.
But these are already quite old-fashioned light sources, after all we live in the age of LEDs! Their only disadvantage is that they are comparatively expensive...
DIY - DIY LED
But with the light emitting diodes a cheap solution can be realized, if you have a little bit of craftsmanship. For DIY LED plant lamps there are different approaches, which we will briefly introduce in the following:
E27 panel as plant lighting
The absolute entry-level class in the DIY sector is E27 lamps, which can be purchased in any DIY store. As they can be supplied directly with mains voltage on the E27 base, they are considered a very cost-effective alternative to the other DIY LED options that require a special power supply unit. The components are extremely easy to get and cheap. Some simple LED bulbs with 7 watts are available for only 1 €.
As inviting as this concept is, it also has some disadvantages.
- Height: The LED bulb itself is already relatively long, plus the base and cabling, so you have to reckon with a height of about 20 cm. This is often wasted space in narrow growboxes.
- Efficiency: Most manufacturers do not set any priority here. Due to the driverless principle, purely technological compromises must be made. 130-140 lm/W are to be expected at most, the mass delivers about 100 lm/W.
- Service life: Due to the housing, which is based on the bulb, the heat dissipation is often insufficient. Therefore, usually only 20,000 hours can be expected.
COBs
Most popular for such DIY LED solutions were long COBs - chips on board - which have the advantage of simpler cabling compared to the equally efficient high power LEDs. Here, however, photons are again generated centrally and must be distributed by suitable optics, which is generally at the expense of efficiency. The bundled power of the COBs in a very small area also requires complex cooling solutions.
The most popular COBs for indoor plant lighting have long been the Cree CXB3590, which can run up to 130W. In order to achieve an acceptable light output of approx. 2.3 µmol/J, this LED chip is supplied with a low current and then needs approx. 50W.
LED strip
In the meantime the hobbyist scene has developed further. In recent years, more and more affordable Mid Power LEDs have been launched on the market, which are more efficient and, above all, provide better light distribution. To achieve this, as many dedicated LEDs as possible are distributed over a large area to achieve a very even illumination.
In the hobby sector, mid-power solutions are usually based on LED engines, which are offered by the major manufacturers for retrofit solutions. These strips - also called Strips or Stripes - are designed to replace neon tubes. Several of them can be combined to form a panel, usually requiring only plug connections. Even though mid power chips usually do not generate much waste heat, a simple heat sink is recommended for efficient and reliable operation. Resourceful hobbyists build a grid from simple U-profiles, on which the strips are mounted.
Disadvantages of LED strips
This is an efficient and, above all, inexpensive way to build efficient plant lighting. However, the Stripes also have disadvantages.
Basically, the LED strips are not designed for plant lighting - to achieve the required intensity, a large number of strips must usually be combined - a tangled mess of cables is inevitable.
In addition, the strips are often not ideal for heat dissipation, as the cheaper variants are usually made of FR4, a synthetic resin. Higher-quality stripes rely on aluminium-core PCBs, which distribute and dissipate heat well.
But what can actually become a problem for DIY LED projects are the mounting options. All that is left for the hobbyist is double-sided adhesive tape, which further impairs heat conduction and in the worst case even loses its adhesion due to thermal stress.
LED boards
A possible solution to achieve high performance without sacrificing efficiency and illumination is Grow LED Boards. These modules are available in numerous variants. Mostly they are used with Mid-Power LEDs, like the efficient Samsung LM301B loaded.
Crescience has developed the FLUXengine as a mid-power board to establish a DIY-friendly solution that allows you to build very individual grow LEDs yourself.
For someone who wants to build a lighting system for indoor gardens themselves, these LED engines are ideal. The FLUXengine can be screwed on standard grooved profiles, which in most cases even saves the purchase of an own heat sink. With a solid, three millimetre thick aluminium board, the FLUXengine is optimised for best heat dissipation. The dimensions are based on the standard dimensions for furniture and growboxes, so that the ideal lighting can be constructed for every surface.
Crescience also provides reference designs and comprehensive documentation for do-it-yourself construction. However, we would like to point out that do-it-yourself plant lighting is only recommended for qualified professionals.
