Solar Conversion

Factor e Farm would like to announce that we are finally in the process of converting our operations from generator-based electricity to 100% solar electric.

Thanks to Ronny’s behind-the-scenes work while he was with us this winter, we recently received a donation of solar cells from Ersol. Ersol is a German wafer and solar cell manufacturer, based in Erfurt, which specializes in silicon-based photovoltaic products.

If you are interested in their products, please contact Nicole at global sales –

The solar cells that we received are sufficient to run all of our needs: internet, lights, shop tools, juicer, etc. We look forward to running a freezer without having to turn on the generator. Perhaps we could even start to keep up with washing our clothes with our old-style Philco Bendix washer-wringer from the 1950s.

The Lister 3 kW electric generator – which we ran on oil, diesel, and biodiesel, will stand proudly as ever-ready backup and as a showpiece.

If you observe our digital fabrication program for CEB machine production a few posts ago – you’ll see that the solar cells are its central power source. This is 100% off-grid eco-industry – and not bad for the humble beginnings of Factor e Farm.

We have a large forklift battery pack to support the operations. Our present challenge is to frame the solar cells into panels so that we can charge this battery bank. We are looking for help from any of you who have framed or encapsulated cells into panels – we’d like to learn from your experience. The solar cells look like this from the front and back:

Tabs need to be soldered on the cells, so that we can string the solar cells into panels. We are also considering 2-3 fold solar concentration to maximize electrical output – especially on cloudy days. If there’s anyone in the audience who has put together solar panels from cells – especially in the low-ratio concentrator configuration- please let us know. We are looking for detailed process and materials sourcing suggestions.

The next frontier for us is to produce our own inverters. We would like to be in a position to run even our high-power welder – which requires 9 kW – entirely on solar energy. We have sufficient battery power to handle this – but not a 10 kW inverter. These are expensive – $10k. We are interested in the design and deployment of a scalable, open source inverter. This is not rocket science – circuits are readily available for the asking from electrical engineer types – but to produce an integrated system that is both scalable and open source documented is the next question. For example, if basic units are on the 1 kW scale – a string of 10 of these makes for 10kW. I predict a cost of about $100 – and possibly as low as $25-50, per kW unit.

Then again, another option for the welder would be to run it off the battery bank directly. If anyone has done that with the Millermatic 200 MIG welder – we’d like to know.

How exciting – welding metal by using solar rays that come to us for free.


  1. Reto

    Sorry that I’m not able to help in this concern – although I look forward for any progress. Just want to let you know that I follow your project with big interest – from Switzerland. I’m also heading towards more sustainability and self-sufficience (and blogging about it, “unfortunately” in German). BTW: saw your interview on Global Swadeshi, which gave me great insight.

  2. Marcin

    Reto, just looked at your blog – you are going in a similar direction as we are. Can you tell me more about the specifications of the mud pump you use to plaster your walls? That’s an incredibly time-saving device compared to plastering by hand – we’re still not finished with stuccoing our earthbag home.

    View our progress on solar cell encapsultion here –

  3. Richard

    Maybe someday we will find a way to concentrate enough solar heat to burn gas at high temperatures…. solar welders anyone?
    Sounds like an awesome idea for producing the inverters. about $500 (or $300 for the more conspicuous) is a reasonably sized investment for homes in addition to panels, mounting and batteries. Some of the blue collar folk at work I’ve been talking to don’t find $1 a watt unreasonable, so 3-500 for an inverter wouldnt put too much more heft on the bill.

    Imagine a KW or two of solar per home plus a small windfarm, and you’ve got power for as many as a thousand average sized homes and a CSM facility and common infrastructure (schools, a theatre (who needs tvs?) a computer center/library, a small clinic). Now theres a good community to raise your children in. ah!
    see you folks soon!

  4. […] energy supply (instead of local waste veg oil) based on the PV cells donated by Ersol. You can read more below, but to update that post we will be soldering, assembling and encapsulating the panels in a few […]

  5. mimarob

    I found this side, where they propose to use modified transformers from old microwave ovens, you’d need about 10 broken micros’ and 20 N-type power MOSFET’s for a 9kw unit.