We moved to very rural location in Spain 22 years ago , there was and still is no infrastructure so we use bottled gas for cooking although the oven is still fan assisted , were not large consumers but we still needed a reliable source of electricity . In 2002 I installed a system in the garage using Morningstar and Studer equipment , the batteries were the only thing that ever needed changing , the equipment worked flawlessly for over 20 years until one day a leaky roof above the equipment damaged one of the inverters , that gave me a reason to upgrade from what had become outdated technology and at the same time come up with a way to avoid it ever happening again . I started off by having all the panels replaced by larger and more efficient ones but because we needed power we continued to use the wall to mount the new equipment while I built the unit . I prewired and pre drilled everything to accommodate the equipment so i was then able to moved everything across in a few hours . I wanted a structure that was movable so the unit is mounted on 4 x 10cm wheels and sits 2cm off the floor , it can be rolled 3 meters without uncoupling the umbilical’s , more than that and it can be completely detached in seconds .
Its rare that the weather is bad enough for us not to be able to fully charge our main batteries however when it has been in the past we used a Honda 2.2 Kw Inverter generator but the time had come when we needed a backup system that could be activated easier and quickly without any effort or technical knowledge ( Wife ) although I still incorporated a generator input which through a couple of cam switches we can select from various charging and power supply configurations for emergency .
Our main batteries are AGM and charged conventionally through an MPPT and two Turbines although the turbines are hardly ever turned on now . The Batteries we installed to act as our backup are Lithium and on a dedicated circuit , they are charged independent of the PV Array circuit by turning on either a DC to DC or an AC charger that’s mounted on the back of the unit . The idea is that they would recharge at the first opportunity when the main batteries next went into Absorption which normally happens by 11am . The calculated the Capacity of the Lithium batteries to match our night time consumption which i knew from historical data , they are sufficient to last two or three nights , more than that would be very unusual in this part of Spain . Day times are never a problem even in the worst weather as I deliberately over panelled while maintaining the advised safety margin for the MPPT voltage . Both circuits incorporate Smart Shunts so they can be monitored online through VRM . When we need to use the Backup batteries we now only have to turn a switch and the Inverter then draws its power from the Lithium batteries relieving the AGMs of any load and their circuit uninfected . Once our AGMs give up there is provision on the unit to add more Lithium batteries so everything will then be more self contained .
The Victron Equipment is mounted on three heavy preformed galvanised steel sections which are designed to be welded to a framework to make external fire escapes , I find them excellent for dissipating heat but as an added `precaution I cut holes behind the MPPT and the DC Charger and mounted small computer fans . The fans are controlled using the Temperature sensors supplied with Multiplus Inverters , those sensors dont require power so I just tucked them between the equipment and the steel back panel and wired them through the relays on the Cerbo . There is an additional large AC fan above the Multilplus as it can get quite warm in our garage during the summer months , this and the lights either side of it which are useful at night are controlled through Alexa as is the AC output into the house from the back of the unit , Alexa of course extends control into our living room or anywhere away from home as its also online .
The Busbars are the same design as others I made and have been using successfully for over 21 years despite not being copper which I couldn’t get hold of here at the time their mass makes for excellent conductivity and they don’t registering any resistance between connections . Each Busbar consist of a 12cm x 12cm x 8mm thick carbon steel plate drilled and fitted with stainless steel countersunk 8mm bolts and serrated nuts . To protect them so they weren’t left exposed and risk a short circuit I bought a red and a grey fire retardant 6mm thick kitchen chopping boards which i cut down to size to cover them , I also bought 8mm blind hole Plastic thumb screws from Temu to secure them .
As an antiques dealer I didnt have much use for tools but I did have a DIY pedestal drill that was given to me plus , a small hand grinder and an assortment of spanners , files and screwdrivers that I had picked up over the years . I cant weld so I bought long lengths of 4cm tubular steel and angle iron which I cut up into around 35 different lengths then drilled and bolted together with over 400 nuts and bolts , once assembled I had to take it apart to be powder coated , putting it back together was a real headache as it wasn’t possible to mark the orientation or number any parts because of the powder coating , the best I could do was to put a small nut and bolt in each of the left hand side pieces which helped a bit by removing almost 50% of the guesswork .
The Huawei tablet provides the ability to configure equipment through Victron Configure or Victron Connect as well as monitoring through the latter and VRM . Ive taken a lot of photographs and labelled the various switches and parts with a description of how/what they do which and added to home screens so they can be quickly swiped through . I also placed a digital file containing simplified drawings of individual circuits .
I completed the unit six months ago and although its not been necessary Ive been trial running the Backup once a week otherwise it could be months between uses , so far Ive been pleased with its performance , there was only one occasion when we were not able to recharge them due to the weather being bad but we switched over to the main AGMs in the morning and the PV output covered our consumption during the day but didnt quite fully charge them so we gave the backup Lithiums a second nights use . The following day when the weather had returned to normal and we were back to running on the Main batteries full time while also charging the Lithiums which were only down to 45% DOC , plenty left for a third night in the unlikely event that they were needed .
Our average daily consumption is only around 3.5kWh although on occasionally we have use as much as 7kWh , while the maximum load at any time has never exceeded 1400 watts . We have an average size house with numerous lights , large flat screen TV, Fridge , Chest freezer , Microwave , a wireless internet supply , outside submersible water pumps for grey water , fans in the summer and a fan assisted woodturner and electric Blankets in winter plus around 20 sockets used for clocks , charging phones ect , kitchen appliances . Our Washing machine is the only appliance that exceeds the inverter if it were to heat the water but its always only ever been set for Cold wash because the water is heated externally by bottled gas . I think we have proved that its possible to live width a small system .
I had a lot of fun making the unit and learnt a lot along the way , you can learn anything if you take the time to read and take advice , as my old grandfather always used to say , “ if you dont know then ask “ , it would be nice if there’s some aspect of it that could prove useful in someone else’s setup .
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