Solar Plastic Molding

Product update, 4/11/2016

SRM2 system now available for pre-order.
See Demo Video

Typical System less than $100,000 complete. Just add molds and plastic.

20 heliostats for heat, two–chamber molding enclosure, pv + battery for motor power, more.

Inquire- and Download PDF Spec

IMAGINE molding high quality plastic parts with no energy bill.   LightManufacturing’s solar plastic molding systems use solar heat from heliostats to make plastic parts..  Our Solar Rotational Molding (SRM®) systems cost less to purchase and to operate than traditional rotomolding systems – and don’t require a building or support structure.  Systems install on unimproved land and operate entirely off-grid.  No gas or electrical connection needed.             

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SRM Advantages:

  • Earn more than your competitors, or reduce price to gain market share.  5-30% finished part cost savings.
  • Zero carbon emissions, low-cost plastic molding
  • Generate carbon-credits
  • Add molding capacity at much lower cost than traditional molding cells
  • Deploy systems seasonally or on a trial basis – SRM systems can be moved / redeployed if desired
  • Easier permitting – no building, grid-tie energy required
  • Easily locate factories close to customers – reduce shipping costs, lead times
  • Economically viable on over 49% of Earth’s land mass.
  • SRM systems ship ‘turn-key’, with everything needed to make plastic parts except the molds and plastic resin.
  • Normal rotational molds can be used, with no modifications except a coat of solar absorptive paint.
  • Cycle times are equal or less than traditional rotomolding.

SRM Overview Video

Frequently Asked Questions
Click question to see answer.

What’s the problem with Rotational Molding?

Rotational molding is a globally-used technique for making large plastic objects.  Over 3.6 billion pounds of plastic are rotationally molded each year.  Unfortunately, the process is energy intensive and uses non-renewable energy sources like natural gas and kerosene.   Over 18.4 trillion BTU of fossil fuel is consumed by the rotational molding process,  generating over 2.15 billion pounds of greenhouse gasses annually.

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How does LightManufacturing help?

LightManufacturing’s patents-pendng process uses sun-tracking mirrors called heliostats, to concentrate solar energy on a rotational mold.   We have developed a uniquely capable heliostat, called the H1.  Heat from the sun directly warms the mold, melting the plastic.  Because the process uses heat directly in the molding process, the system is highly efficient:  75% efficient as compared to typical photovoltaic efficiency of 15% or less.  There’s no need to convert light into electricity, nor does energy have to be transported via expensive transmission lines to market.

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Is the process economically competitive? Doesn’t Solar need subsidies?

Yes.  Unlike inefficient solar electric systems, our solar thermal systems capture and use over 75% of incident solar heat.  Also, the purchase cost of our heliostats and molding systems is much less than the equipment needed for traditional gas-fired plastic molding.

The result?  Lower buy-in costs AND  lower operating costs.   Solar thermal plastic molding out-competes traditional processes without subsidies – a rarity in the cleantech world.


The cost of Because we use the heat immediately to heat our molds,

Solar thermal technology  / CSP is much less expensive than solar electric technology, so the buy-in costs for a Solar Thermal Molding system are much less than traditional rotomolding systems.   Furthermore, the group of heliostats used in a solar thermal molding system can be quickly and easily retargeted from one place to another.  This ‘aimability’ allows us to simplify the design and reduce the cost of typical rotational molding (and vacuum forming) systems.

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Are there other advantages?

Solar Thermal Molding does not require a concrete-floored building, or connection to the electrical grid, or natural gas hookup.  The H1 heliostat arrays can be installed in simple, unimproved terrain.   This further reduces capital requirements to install a Solar Thermal Molding system vs a traditional rotational molding.

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How Large are SRM (Solar Rotational Molding) Systems?

Solar Rotational Molding Systems install into areas as small as 60′ x 60′ (3600 ft2).  However, most of this area is unmodified; it can be left as unimproved land, or even planted with low-height crops.  Here is how the land is used:

  • Heliostat array footprint @ 60′ x 10′ (600 ft2)
  • Target enclosure footprint @ 20 ‘x 8′ (160 ft2)
  • Raw materials, tools, and finished part storage (typical) 300 ft2

Total: 1060 ft2    So, just 30% of the 3600 ft2 total area is occupied by objects.  The balance of the land remains unchanged.  Compared with the concrete-slab required to support a traditional rotational molding operation, SRM offers a far less impactful solution.

Large SRM systems scale as big as needed – 12 systems pack into a single acre of land.

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Does the SRM process use ANY electricity?

Yes – electricity is used to position the heliostats, and electricity is used to drive the two motors in each molding armature.   For small to midsized molds, these motors are 1/2 horsepower and require a total of @ 745 watts peak power. Our Solar Rotational Molding systems include photovoltaic panels, batteries, and charge controllers – you can install an SRM system anywhere.  No grid-tie electricity is needed.

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How much mirror area / heat is needed to mold typical plastics?

Because Solar Rotational Molding uses concentrated solar thermal energy, not solar electricity, it converts a very high percentage of available solar energy to useful heat.  SRM achieves  75% typical efficiency, vs solar electric’s 15-20% efficiency. This efficiency, combined with LightManufacturing’s heat management, positioning, and process control software allow mirror arrays as small as 224 ft2 to generate sufficient heat to mold objects roughly 3 ft x 3 ft x 3 ft.

A key difference between SRM and traditional rotational molding is that SRM heats the mold target by radiative heating (efficient, directly heats the metal) vs convective heating (gas burner heats air, which inefficiently heats the metal).

224 ft2 of focused mirrors yield approximately 17,000 watts of directed heat energy.

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Aren’t most plastic things made in big factories in China?

Most people think of injection molding when they think of plastic manufacturing – this process is very capital intensive, and produces high volumes of relatively small, thin-walled objects – i.e. plastic cutlery, small toys, flashlight bodies, etc.

Rotational molding is best at making relatively large objects – from something 6″ across to very large objects such as 8′ diameter water tanks or 10′ long boats, with walls up to 1″ thick.  These large, heavy objects do not pack efficiently, and shipping them is essentially to ‘ship air’.  As a result, Rotational Molding is distributed across all markets – European Rotomolders making parts for Europe and for export, Asian rotomolders making parts for Asia and for export, etc.  The distributed nature of rotational molding allows LightManufacturing’s SRM process to be deployed as needed in solar-rich regions.

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Isn’t all plastic molding environmentally ‘bad’?

Rotational molding, and Solar Rotational Molding (SRM) can use a variety of plastics – including virgin (new) material, and recycled material.  New plastic made from fossil fuel sources has environmental issues, but the longevity and reliability of rotationally molded plastic parts can make them compelling ‘green’ choices over the life of the product – particularly if some recycled content is used.

Thermoplastic objects are highly recyclable, a significant benefit in end-of-life reuse.  Solar Rotational Molding is an excellent way to close the loop and reuse post industrial and post consumer plastic for new products.  Finally, new plant-based plastics offer a source for high performance, rotationally-molded materials.

By removing energy costs from the molding process, SRM makes molding ANY plastic more sustainable and affordable, while reducing greenhouse gas and particulate emissions.  SRM applies Concentrated Solar Power / CSP to a globally-deployed industrial ”smokestack process”, and converts it into a sustainable manufacturing process – a cleantech ‘good citizen’.

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What Polymers can the Solar Manufacturing Process Use?

Any rotational molding resign can be molded using SRM, including polyethylene, polypropylene, nylon, and other polymers.  The SRM process uses CSP / Concentrated Solar Power to achieve any desired molding temperature, and often with cycle times less than ordinary rotomolding.  Contact us to learn how we can help convert your traditional operation to a low-cost, sustainable manufacturing operation.

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Want to learn More?  Contact us!