About us

About Franz-Josef Feilmeier

Franz-Josef Feil­mei­er, second of three child­ren, grew up in a home whe­re respect for the envi­ron­ment play­ed a major role.

The paren­tal busi­ness, an agri­cul­tu­ral warehouse offe­ring GMO-free “food for ani­mals,” is to be made ener­gy self-suf­fi­ci­ent with pho­to­vol­taic sys­tems. Clean ener­gy is just as important as clean food.

After stu­dy­ing tech­ni­cal busi­ness admi­nis­tra­ti­on at the TH Deg­gen­dorf, half a year in Chi­na, whe­re he alre­a­dy expe­ri­en­ces e-mobi­li­ty on a grand sca­le with elec­tric buses in 2005, Franz-Josef moves on to his next pro­fes­sio­nal sta­ti­ons: Diplo­ma the­sis on solar tech­no­lo­gy in Ham­burg, con­s­truc­tion of solar cell fac­to­ries based in Kon­stanz and then buil­ding pho­to­vol­taic sys­tems with fri­ends back in Lower Bavaria.

Franz-Josef Feilmeier
Franz-Josef Feil­mei­er: Foun­der and Mana­ging Direc­tor of FENECON GmbH 


Roof­top and ground-moun­ted sys­tems had grown in size. As full feed-in pro­jects, they were gene­ral­ly invest­ment pro­per­ties. But the ener­gy tran­si­ti­on needs more than just a dumb feed-in when the sun is shining.

The start-up pro­ject of FENECON (Feil­mei­er New Ener­gy Con­sul­ting) was a grid-con­nec­ted PV self-con­sump­ti­on sys­tem wit­hout excess feed-in on the paren­tal farm to maxi­mi­ze self-sup­p­ly with intel­li­gent sto­rage and ener­gy manage­ment while avo­i­ding any feed-in and the asso­cia­ted grid expansion.

The mar­ket was not yet fami­li­ar with such pro­ducts, so we went back to BYD in Chi­na, desi­gned appro­pria­te power sto­rage sys­tems tog­e­ther with our Chi­ne­se fri­ends, and tes­ted and opti­mi­zed them in our gara­ge at home. Many an important com­pa­ny has been foun­ded in a garage.

The vision is the 100% energy transition and a better future
for us and future generations.



Lower Bava­ri­an Foun­der Award The com­pa­ny alre­a­dy included six employees and moved from the 30m² office in the Deg­gen­dorf busi­ness incu­ba­tor into an office buil­ding with warehouse in the dis­trict Fischerdorf. 

Days of rain and high water. A dam of the Isar breaks, the who­le Fischer­dorf is under water and so is the who­le camp and our vehic­le fleet. Ever­y­thing is des­troy­ed.
10 strong-wil­led employees strugg­le with dama­ge con­trol for more than half a year. We dry, clean, repair wit­hout inco­me, becau­se that’s how long it takes until the insu­rance com­pa­ny trans­fers the first funds and we can buy new goods. The set­back was harsh, but as a time of reflec­tion and deve­lo­p­ment, it also repres­ents the basis for new con­cepts and later ground­brea­king developments.

FEMS is born, a modern moni­to­ring and ener­gy manage­ment sys­tem for sto­rage and PV sys­tems, able to switch loads depen­ding on the sta­te of char­ge. From now on, every BYD sto­rage sys­tem in Ger­ma­ny will be equip­ped with this deve­lo­p­ment from Deggendorf. 



Tog­e­ther with BYD, we are laun­ching the first series-pro­du­ced com­mer­cial sto­rage sys­tem on the Euro­pean market.

The first test cus­to­mer is once again the Feil­mei­er father and the test labo­ra­to­ry is once again the gara­ge, which is now equip­ped with many test and mea­su­re­ment systems.

BYD is brea­king new ground with a com­pa­ti­ble bat­tery - and FENECON is com­bi­ning it with dome­stic inver­ters.
The FEMS now con­trols ever­y­thing and can do more and more.


Ste­fan Feil­mei­er, Franz-Josef’s brot­her and head of FEMS deve­lo­p­ment, brings his expe­ri­ence from India, from the Linux world into the sys­tem. His visi­on is to make FEMS the ‘ope­ra­ting sys­tem for the ener­gy tran­si­ti­on’. It is to beco­me open source and acces­si­ble to ever­yo­ne. The Open­EMS plat­form is created.

The con­cept is imple­men­ted, so we sim­ply make our years of expen­si­ve soft­ware deve­lo­p­ment available to ever­yo­ne as open source code. The gre­at effect of a manu­fac­tu­rer-inde­pen­dent and open plat­form for sim­pli­fy­ing and acce­le­ra­ting the decen­tra­li­zed ener­gy tran­si­ti­on should only beco­me com­pre­hen­si­ve­ly appa­rent in the next few years.


In the same year, we recei­ve the Han­dels­blatt Ener­gy Award for our “ener­gy part­ner model”, which aims to avo­id new depen­den­ci­es and ins­tead achie­ve a wide ran­ge of attrac­ti­ve elec­tri­ci­ty offers with an Open­EMS sto­rage sys­tem. As such a young, small com­pa­ny with just 30 employees, we recei­ve this major, high­ly regard­ed award.

In 2017, we are start­ing to incor­po­ra­te used vehic­le bat­te­ries into sta­tio­na­ry sto­rage sys­tems and to deve­lop con­cepts for “living spa­re parts sto­rage” of vehic­le bat­te­ries for major car manu­fac­tu­r­ers.
In the mean­ti­me, we have beco­me the tech­no­lo­gy lea­der in this seg­ment and have alre­a­dy been able to inspi­re many manu­fac­tu­r­ers with our inno­va­ti­ve and fle­xi­ble “full-pack approach”.


Open­EMS is now estab­lished at many com­pa­nies and many rese­arch pro­jects work with it, so that tog­e­ther the Open­EMS Asso­cia­ti­on e.V. is foun­ded, which dri­ves the fur­ther deve­lo­p­ment of the plat­form. Ste­fan beco­mes chair­man of the board of the sup­port­ing association.

It’s the time when all sto­rage manu­fac­tu­r­ers are moving into the next growth pha­se - which for most means being bought and incor­po­ra­ted by a con­ven­tio­nal cor­po­ra­ti­on. That would not be our way. We are a medium-sized 


fami­ly busi­ness and want to remain so in order to Visi­on of sus­taina­bi­li­ty and decen­tra­li­zed ener­gy tran­si­ti­on to be able to move for­ward freely. 

We qua­li­fy as an ‘impact com­pa­ny’ and gain Bon­Ven­ture, an eco-social fund as a part­ner that sup­ports our social and envi­ron­men­tal goals and grants us free­dom of choice. 

In 2019, more than 40 high­ly qua­li­fied employees are alre­a­dy com­mit­ted to our mis­si­on of ener­gy engi­nee­ring, some of them also at our first exter­nal pro­duc­tion site in Künz­ing.
Open­EMS recei­ves hig­hest reco­gni­ti­on as Euro­pean Ener­gy Sto­rage Highlight.


We grow to over 60 employees and it is still main­ly engi­neers in the team. We can more than dou­ble our sales. Many peo­p­le invest in smart home sto­rage with emer­gen­cy power during Coro­na and our pro­ducts per­fect­ly meet the expectations.


We accept the EES Award, the hig­hest distinc­tion in the sto­rage world, in a
online award cerem­o­ny with a loud cry of jubi­la­ti­on. Our indus­tri­al series for
Use of elec­tric vehic­le bat­te­ries in con­tai­ner sto­rage - and once again the
Open­EMS and its many pos­si­bi­li­ties - have con­vin­ced the jury.

To make com­mer­cial and indus­tri­al sto­rage available to even more cus­to­mers, we foun­ded FERESTO GmbH (FENECON Ren­tal Sto­rage), which offers lar­ge-sca­le sto­rage for fle­xi­ble ren­tal. The gre­at demand shows that we have also hit a gap in the mar­ket here.

The FENECON Home will be laun­ched on the mar­ket in May. A com­ple­te sys­tem to which we imple­ment future via­bi­li­ty as DNA and install ener­gy manage­ment as a head on the bat­tery. The lear­ning sys­tem loads the elec­tri­ci­ty sto­rage sys­tem in advan­ce and ensu­res that PV sys­tems are not shut down. The sys­tem is nomi­na­ted for the EES Award but even more important: instal­lers and cus­to­mers are enthu­si­a­stic becau­se the FENECON Home is instal­led and com­mis­sio­ned in no time and con­vin­ces with relia­bi­li­ty and open­ness to the future. Cus­to­mers can still choo­se their own elec­tri­ci­ty pro­vi­der and inte­gra­te sui­ta­ble heat pumps, hea­ting rods or char­ging infrastructure.

In June, we will cele­bra­te our 10th anni­ver­sa­ry with our team, which now num­bers around 80 and is working hard to pro­mo­te the ener­gy tran­si­ti­on. Our part­ners include sto­rage who­le­sa­lers, ener­gy sup­pli­ers and gene­ral con­trac­tors, to whom we would like to express our sin­ce­re thanks for the good coope­ra­ti­on and trust they have pla­ced in us, even in dif­fi­cult times. We look for­ward to the next many years with all of you.

In Octo­ber, we are one of only two pro­jects fun­ded in Ger­ma­ny to recei­ve a grant from the EU Inno­va­ti­on Fund. The fun­ding of €4 mil­li­on will enable us to build Europe’s lar­gest 2nd Life elec­tri­ci­ty sto­rage fac­to­ry, the Bat­tery­Re­Fac­to­ry in Iggen­s­bach, near Deg­gen­dorf. Here, start­ing in 2024, we will manu­fac­tu­re new pro­ducts from used e-vehic­le bat­te­ries and pre­ser­ve raw mate­ri­als that are alre­a­dy in Euro­pe here and make them usable again. Our under­stan­ding of sus­taina­bi­li­ty and the ener­gy tran­si­ti­on makes this step imperative.

In Decem­ber, we are releasing new FEMS apps for incor­po­ra­ting time-vary­ing elec­tri­ci­ty rates into FEMS. Her­eby the FENECON elec­tri­ci­ty sto­rage sys­tems can par­ti­ci­pa­te even more actively in the ener­gy tran­si­ti­on, save cash for our cus­to­mers and reli­e­ve the elec­tri­ci­ty grids. Ide­al for resi­den­ti­al, com­mer­cial, indus­tri­al and loa­ding parks.

We are gra­teful and plea­sed that our employees came through the year in good health. This is a gre­at gift.


The the­me of the year is Unleas­hed, as gre­at things will start that were pre­pared in 2021.

  • Thus, the con­s­truc­tion of the Bat­tery­Re­Fac­to­ry will start in late fall and many other novel­ties will be on their way.

  • In May, we recei­ve The Smar­ter E Award for Out­stan­ding Pro­jects for the Indus­tri­al Sys­tem, which pro­vi­des grid ser­vices as a living spa­re parts store for elec­tric car bat­te­ries in a for­mer coal-fired power plant. 

  • We are now 120 com­mit­ted ener­gy users, with new ones joi­ning every month (as of August 2022).

  • New pro­ducts will enter the mar­ket this year. More about that in due course.

We look for­ward to the next many years with all of you.

Our success is in the team

  • A young team of high­ly qua­li­fied and high­ly moti­va­ted colleagues.
  • Inter­na­tio­nal, open-min­ded, tolerant.
  • Suc­cessful tog­e­ther: flat hierarchies.
  • Part­ner­ship with sup­pli­ers, cus­to­mers and ser­vice providers.


Our ener­gy part­ner model for mar­ket par­ti­ci­pa­ti­on with elec­tri­ci­ty sto­rage con­vin­ced the jury, which award­ed us the Inno­va­ti­on Pro­mo­ti­on Pri­ze from over 30 applications. 
The award is given for out­stan­ding suc­cess in buil­ding busi­nesses. It is the hig­hest award for foun­ders and entre­pre­neurs in Lower Bavaria. 
Win­ner of the Han­dels­blatt Ener­gy Award in the cate­go­ry “Smart Home” with our FENECON ener­gy part­ner model. 
Win­ner of the EES Award with our Indus­tri­al Con­tai­ner Storage. 
Lower Bava­ri­an Foun­ders Award 2022: FENECON hono­red in the “Up-and-Coming” category 
Win­ner of The Smar­ter E Awards in the cate­go­ry “Out­stan­ding Pro­jects” with our Indus­tri­al Con­tai­ner Sto­rage in the pro­ject “Con­tai­ner-based Bat­tery spa­re part warehouse” 
Gewin­ner des EM Power Awards: unser FERESTO Ren­tal Sto­rage Geschäftsmodell 
Gewin­ner des ees Awards: der nach­hal­ti­ge Indus­trie­spei­cher FENECON Indus­tri­al L 
EUPD Rese­arch TOP Brand 
Solar Pro­sumer Award 
TOP 100 Inno­va­tor des Jah­res 2023