Solar energy – generation & applications – AC vs DC

‘High Voltage’ – transmission & usage

Following on from our recent post on our Solar Power System – On Grid Project, the observation has been made that it’s rather inefficient to generate power as DC electricity, and convert it to a higher AC voltage, before converting it back again to DC to suit many consumer applications.

Voltage multiple conversion

The issue of use of AC or DC is not a new one. Famously, in 1893, Thomas Edison who promoted the generation and use of DC ‘lost’ the battle to George Westinghouse who gained acceptance for the generation of AC at the Chicago World’s Fair, since it was more efficient in long-distance transmission.

This has been the situation for more than a century and still applies with generation at remote power stations and transmission at high AC voltage to feed and satisfy local demand. The 240V (in the UK) AC mains electricity that is delivered to a household is perfectly suitable in this form for domestic high power applications i.e. cooker, washing machine, etc. On the other hand, electricity is used for variety of low-voltage DC devices and gadgets e.g. phones, TVs, computers and so on, contain power adapters converting AC to DC and stepping down to typically 12v or 5v USB. Lighting is traditionally AC, but with advancement in LED technology could be of a lower DC voltage.

The development of locally generated solar energy changes things somewhat. The generation output is low voltage DC. The majority of this generated electricity is utilised locally. Excess energy can be stored in batteries, which are also low voltage DC. This could be used in this form, but in order for a household to be able to supplement locally generated energy, when the sun doesn’t shine (night time / winter), it still has to be wired to receive AC from the grid-based electricity. Also, to facilitate the export of excess energy (an increasingly valuable benefit of domestic solar power generation), the locally generated electricity must be converted to grid-compatible AC, using an inverter.

It should be the case that houses of the future are designed and built with solar panels on the roof. Indeed, it is now the case they are cheaper that slate, and so the materials and labour charges would be negligible costs if part of the build rather than as an add-on. In which case, the building could be designed with 12V DC and 5V USB supplementary to the 240V AC for mains wiring, feeding appliances directly at the type of voltage they require, eliminating power rectifiers and most voltage converters.

This ‘direct supply’ is already demonstrated in our Solar energy off-grid eBike charger project with the generated supply connected to a AA / AAA / C / D / PP3 battery charger using its 12V DC input (bypassing a 240V AC input, which requires internal conversion). The 12V supply also feeds LED lights without voltage conversion.

Charging batteries from 12V DC Solar Energy

Similarly, the 5V USB outputs of the solar charger controller can charge iPhones and other gadgets.

Solar Charge controller with 5V DC USB sockets

‘Highway to Hell’ – EV charging & V2X

We know that Electric Vehicles (EVs) are going to be increasingly in use and will gradually take over from petrol and diesel engines.

PHEV charging

And so the ability to charge these at home will be increasingly important and convenient. Some cars are already of a Plug-in Hybrid Electric Vehicle (PHEV) type, meaning that they can be charged from a domestic UK 240V AC supply for local use. 

Another key development is the concept of EV batteries being used as supplementary storage for a household, so called ‘Vehicle to Home’ (V2H), ‘Vehicle to Building / Business’ (V2B) or ‘Vehicle to Grid’ (V2G) [collectively V2X indicating bi-directional, as opposed to single direction V1G], charging at low demand and discharging when household usage is greater, or to take advantage of higher export pricing.

V2X Charging types

The AC supply is needed to be converted to a DC voltage useable by the car batteries, and similarly the car’s electricity needs converting from DC to AC for household export. There are two ways of achieving this, by having a converter in the charger or the car. But if the premises has its own source of accessible DC power, ideally sourced from locally generated solar energy, then this conversion would be unnecessary.

AC vs DC charging

Another issue is that UK 240V AC is limited to 13A supply from standard household sockets (for most domestic use) providing slow charging at 3kW. A dedicated charging point using a UK Type 2 connection is an improvement with direct connection to the mains consumer unit, providing charging at 3.6kWh from a 16V AC supply or 7.4 KW from a 32V AC supply. Faster charging is possible with 11kW from 32A AC supply or faster still with 22kW from 63A AC supply, but these are more expensive, beyond the available power of many households and require a 3-phase supply.

The European Union has specified the Combined Charging System (CCS) standard to permit both AC and DC charging. Much faster and more efficient charging at 100kW and beyond is possible using DC charging, eliminating the conversion in the vehicle. However, this is currently an even more expensive solution and limited to EVs that can accept a compatible DC input. Charging at commercial sites such as motorway service stations offer a variety of standards, including the CCS (Europe), CHAdeMO (Japan), GB/T (China) or Tesla Supercharger (propriety).  

EV charging service station offering both CHAdeMO and CCS standards

This conversion and compatibility issue is not confined to motor vehicles. As highlighted in the Solar energy off-grid eBike charger project, conversion using an inverter is necessary from the 12V DC power generated from the Solar Panel and stored in the battery, to 240V AC used by the required charger, which then converts again into 36V DC. The problem is not just related to type and size of voltage, as the lithium batteries used require special adapters to perform the charging correctly. It would be possible to produce these fed from a specialist DC adapter, but such chargers are more difficult (and expensive) to obtain, given that the domestic supplies are generally not available in this form and so consequently the demand for these products is not yet there.

‘Thunderstruck’ – Solar powered cooling (mini project)

Given the current heat-wave and the likely-hood of more temperature extremes as a result of climate change, coupled with cost-of-energy crises and possible supply shortages, it seemed appropriate to build another solar power project, this time focusing on powering a cooling fan with energy from the sun.

The concept is relatively straight-forward: using solar energy to assist with cooling. When sitting out and the sun is shining and the temperature is too hot, the sensible thing to do is shelter under some shade. But when there is little-to-no breeze, even in the shade it gets too hot to bare. In which case, a simple fan can help. The one selected was an old, cheap USB model, which provides a limited amount of cooling, but doesn’t require much energy to operate. Also chosen was a small, also old, and low-cost 6V solar panel, which provides just enough energy to power a USB device using a suitable conversion lead.

Solar powered fan

But this isn’t particularly robust since a slight drop in sunshine can stop the set-up working. Hence this has been additionally paired with a battery power bank, which can simultaneously be charged with the solar energy whilst also powering the fan.

Solar powered fan with battery bank

Naturally, the battery pack can be charged separately – ideally powered by locally generated and stored solar energy!

Charging the battery bank from solar energy

‘For those about to Rock’ – the Electric future

Hopefully this has been food for thought into the exciting fast developing world of solar power generation and the electric future. Please get in touch if you have questions, comments or ideas to share. 

@YellowsBestLtd our mission is in “Keeping Customers Operational”. We’re always keen to enhance our range of #business services, increase the #enterprise infrastructure we support and expand our mix of #sustainable solutions we offer for supply and maintenance of new and legacy #technologies and products for our customers. 

Please help us understand your management services or solutions requirements, whether you’re implementing new systems or maintaining existing infrastructure networks to serve your operational business needs. 

Solar Power System (on-grid) project

‘Free’ electricity from the sun

Obtaining low-cost renewable solar energy has always had much appeal, but historically the investment costs has been rather off-putting, especially in the U.K. where it is perceived that the climate doesn’t provide a reliable enough amount of sunshine.

Available sunlight for power generation

However, in recent years a number of things have changed this evaluation. Performance improvements in solar panels and associated power inverters have resulted gains in energy creation, coupled with the availability of modern battery arrays substantial enough to store the energy produced for later reuse. At the same time, shocks to world fuel prices have results in a rapid shorting of the ‘payback period’; once it was considered that a typical household solar installation would take in the order of 25 years to recoup the investments costs. This has tumbled to around an estimated 8 years based on calculations made last year, and taking into account the recent price increases for domestic electricity supply, the period could be approaching 4 years with further shortening likely as energy prices continue to rise. The recent removal of VAT by the UK government on the implementation of solar energy systems is an added boost.

One additional further benefit that has recently arisen is the introduction by some power utility companies, such as Octopus Energy, of ‘agile’ export tariffs, which pay increased amounts at peak demand times. This can be taken advantage of by the use of smart meters, supplying surplus generated or stored energy to the grid at the best times to maximise revenue, offsetting the purchase of electricity from the grid at other times.

Given that the future is anticipated to require increasing use of electricity to provide power for EV cars and hybrid vehicles, generating your own electricity makes increasing sense. 

Overview of our implemented system

Solar Power System overview

Given the now obvious benefits of a solar energy, we have acted accordingly and implemented a system, which has the following component parts:

  • 13x 385W JA Solar Monocrystalline Panels with PERC technology, limited by the available roof space, but sufficient for energy needs.
  • Alumero Mounting accessories & Tigo Optimisers to enhance performance when part of the solar array is shaded.
  • Luxpower Hybrid Auto Inverter, 16A single phase, to convert the generated 12V DC electricity to 240V AC for household consumption or export.
  • 4.8 kW Aoboet Uhome battery storage array to store excess energy for later use.
  • AC and DC isolators to connect the component system parts.
  • Generation meter to measure energy production.
  • Wifi Monitoring portal for displaying instantaneous and historical performance.

The calculated annual yield for this system is 3,679kWh, which should be enough to fulfil the household’s electricity needs, estimated at 3,207kWh based on previous usage. 

Solar Panels – the ‘heart’

Monocrystalline Solar panels

Key to the collection of energy from the sun are naturally the solar panels. These vary in size, and technology is improving continuously, so the latest available are more efficient than previous generations.

Those selected for this project were 13 x 385W JA Solar Monocrystalline Panels with latest PERC (Passivated Emitter and Rear Cell) technology. Monocrystalline are more expensive but more efficient, with a longer lifespan than other types available. PERC technology improves light capture near the rear surface, optimising electrons flow and thereby achieving higher efficiencies.

Solar Panels installed on the Roof

The amount produced by a solar array naturally depends on sunlight hours and will be much lower with poor weather or as daylight reduces, whilst household electricity demand also varies during the day.

The ultimate aim of using solar power is to reduce as far as practically possible the need to source energy from the grid. Consequently, a larger array of modules than those just to meet the typical usage amount is needed to ensure adequate production whatever the weather, with the excess being stored or exported. 

Mounting fixtures
Optimisers

Alumero mounting kits were used for fixing the solar panels to the property roof, together with Tigo optimisers which maximise the generation from each panel. Without such optimisation, the power output from all solar modules can be reduced when some of the array is in shade. 

DC Isolators

DC isolators connect two ‘strings’ of series connected panels to the Hybrid Inverter.

Hybrid Inverter – ‘the brains’

In order for the system to be truly useful, power conversion and energy management functions are needed, to ensure a seamless and uninterrupted supply of electricity from the available sources i.e. an appropriate mix of the local generation, storage and grid supply. Chosen for this installation was a Lux Hybrid Automated 16 Amp single phase inverter.  

Inverter

The Hybrid Inverter ensures that when solar energy is available i.e. during daylight hours, this is firstly routed to provide for domestic consumption, and then used to charge the battery storage (as required, if not full). Any additional energy is exported to the external grid. When there is not enough energy generation from the solar array, the hybrid inverter routes the energy storage to the household, and when this is depleted, electricity is imported from the grid in the usual way. Critically, where to source electricity from is completely seamless such that the domestic consumption is never interrupted and the household is unaware of these ‘decisions’ being made.

It’s the inverter’s job to take the DC electricity produced by the solar panels and turn it into 240V AC electricity for household use. It’s a sad fact that many domestic appliances then take this 240V AC and convert it back to DC and lower voltages like 12V and 5V; this double conversion adding theoretical inefficiencies. But this is simpler to implement than rewiring the entire building and trying to then integrate with power to and from the grid.

AC Isolator
AC Isolator

AC Isolators connect the Inverter’s output to the household electricity supply.

Batteries – ‘the memory’

Quite literally, ‘saving for a rainy day’ is the function of the batteries, which add to the capability and capacity of solar power generation. They are effectively ‘optional’ since the system can be run without them. But since there is a huge natural variation between maximum sunlight and night-time, it makes sense to capture excess energy at peak times, and use this when sunlight is not available or sufficient. 

Chosen for this project were 2x Aoboet Uhome-LFP 2400 providing 4.8kW of storage capacity.

Batteries

At the beginning of a day, the batteries are naturally somewhat depleted, and therefore excess solar energy is initially used to charge them. Once full, they remain ‘on standby’ until later when generation is unable to fulfil the immediate electricity needs, in which case they start discharging their stored energy. Ideally, they will not become completely depleted over the course of the day and night, so that energy is not needed to be imported from the grid.

Grid – import / export

Electricity from the grid is the “insurance” for times when the solar energy is not able to fulfil demand. Naturally, this is likely to be due to a lack of winter daylight hours and/or poor weather, which of course has to be paid for.

Generation Meter

But at other times, there will be an excess of energy that can be exported to earn back some of these costs. A Generation Meter as part of the solar energy system enables this export of electricity.

Smart Meter
WiFi Monitor

The bi-directional energy flow is measured with a ‘smart’ meter using a suitable import / export tariff from the Utility company, such as the Octopus with their Agile tariff, and displayed on an associated WiFi monitor.

As to be expected, the amount paid by the Utility for kWh export is considerably less than that charged for import, so it’s worth making best use of the generated and stored energy as much as possible, like running appliances when the sun shines!   

EPS socket

An EPS (Emergency Power Supply) socket was additionally included in this project. Though optional, it was chosen for providing ‘backup power’ from the solar energy system in the event of a power outage from the grid supply. It is standard practice in such an event to shut off the export to the grid from solar energy systems to avoid difficulties whilst restoration work is in progress. But during such a period, the household can make use of the generated and stored local energy, for a limited time and restricted to a maximum of 13A. Avoiding excessive consumption, it should be possible to maintain a local supply for 12 hours, assuming a fully charged battery array.

MCS Certificate

To complete the project to become an ‘energy generator’ (as well as satisfying own consumption needs), an MCS (Microgeneration Certificate Scheme) certificate is issued, together with receiving acceptance documentation from the DNO (District Network Operative). This then allows the establishment of the export tariff with the Utility provider so that payments for excess energy exported will be made. 

Operating performance

A WiFi Portal provides the householder with an overview of the current operation of the solar energy system, displaying instantaneous status and historical energy performance for tracking generation yield and import / energy export.

WiFi Portal

Initially, it can be reported that average energy yield is around 0.86kWh, ranging between a typical peak of 2-4kW during the day and zero at night, compared with average consumption of approximately 0.35kWh, with the excess charging the batteries in the morning and exporting to the grid during the rest of the day. During the night, the consumption is met from the battery storage, with the batteries depleted to around 11% by the next day. It is noted that even during relatively cloudy days, at least around 10% of the 5kWh maximum power is generated, enough to at least meet the immediate consumption needs and even provide some battery replenishment.

A complete picture of the operating performance of the solar energy system will be known after a full year, taking into account the peak of summer and the shortest winter daylight period. Rising costs of electricity will also impact on the longer-term cost savings anticipated. 

Conclusions

Hopefully this ‘project description’ is of interest and perhaps of use to anyone contemplating installing a Solar Energy system at their home or office premises. Please feel free to get in touch if you would like us to provide consultancy advice (on a no-obligation FOC basis) leading to a quotation for establishing your own system, or just to gain an in-depth appraisal and more information from our first-hand experience of implementing a Solar Energy system. 

System Schematic

Our summary of conclusions at this stage having now implemented a system are:

  1. Solar energy collection has developed rapidly in recent years, particularly now that home energy storage is practical enough to capture excess energy during peak daylight and release it for use during the night or whenever demand exceeds generation.
  2. Although such systems are still a significant investment, given the recent escalation in energy costs, the ‘break-even’ point has reduced dramactically and the trend is for energy costs to continue to rise thereby making the payback period increasingly shorter.
  3. An attractive feature is the notion of being paid to supply energy to the grid, though it should be noted that currently at best this is 7.5p per kWh, so unlikely to be a significant revenue source. But it does mean that energy bills over the longer term will be vanishingly small.
  4. The contribution to the nation’s renewable energy mix helps in a small way to aid the drive to reduced carbon emissions and tackle climate change. 
  5. Naturally, a suitable oriented roof or land space for solar panel installation is required, as well as a location for housing the inverter and batteries (loft space is ideal). Plus, it should be noted that a PV cable needs to be installed (most likely running down the outside wall of the building) to link the inverter to the consumer unit.
  6. Should power cuts from the grid occur in the future, the solar energy system is capable (thanks to the EPS socket) of providing power for a limited period to maintain household electricity use.
  7. With the increasing use of electric cars (all new will need to be at least hybrid by 2030), being able to source local renewable energy will make increasing sense.

@YellowsBestLtd our mission is in “Keeping Customers Operational”. We’re always keen to enhance our range of #business services, increase the #enterprise infrastructure we support and expand our mix of #sustainable solutions we offer for supply and maintenance of new and legacy #technologies and products for our customers. 

Please help us understand what would be of interest to you by getting in touch to discuss your management services or solutions requirements, whether you’re implementing new systems or maintaining existing infrastructure networks to serve your operational business needs. We look forward to hearing from you.

Challenging times demand time for a change!

New “UK” launch

It’s been a challenging time for businesses generally, and particularly in the United Kingdom, with Brexit in many cases adding cost and time to trading, and Covid-19 restricting travel and networking.

So it seemed an appropriate time to launch a new varient of the Yellows Best Limited website, now additionally utilising “.co.uk” as a signifier of commitment to our home market location.  

Keeping Customers Operational

The new YellowsBest.co.uk promotes the same blend of Services and Solutions for “Keeping Customers Operational”, but presented in a different and modern single-page layout, making it particularly mobile device-friendly where ‘vertical scrolling’ is more appealing than using the traditional ‘horizontal tabbed’ layout.

We hope this provides Customers old and new with a welcome alternative, though the original YellowsBest.com will continue to be maintained, along with it’s associated blog for ‘informal’ views and news updates.

Assisting with your requirements

It would be interesting to receive feedback as to how useful you may find this additional site, and whether there is anything else you’d like to see featured.

Of course, @YellowsBestLtd online content ultimately serves the purpose of highlighting the types of services and solutions we can provide. Customers may therefore be prompted to get in touch to discuss their specific requirements, which we can usually assist with.

Rest assured, if you use either contact address:

enquiries@yellowsbest.co.uk

enquiries@yellowsbest.com

we’ll receive your message and will be in touch by return. We look forward to hearing from you! 

‘Dynanet’ Telecoms – ‘Rampdown’ notice

Phased Discontinuation of Production – 31st May 2019 – 31st January 2020

The production of the ‘Dynanet’ family of PDH Transmission telecoms products, first introduced by Nokia over 20 years ago, and continued in recent years by DNWP, is finally being ended.

This product range has well served Public Operator and Private Network Customers across the Telecoms, Utilities, Transport and Public Safety markets with high availability mission critical infrastructure, and indeed some networks are continuing to provide good operational service. 

Essentially almost all the old equipment items, with a very few exceptions such as the TPS64, are being completely discontinued in a phased way according to these milestones, which have already commended:

31st May 2019 – DM8 Multiplexers, DF2-8 Optical Terminals, RPSA

31st October 2019 – DM2 Multiplexers, Subs/Exch & VF Cards, DN2 IU2, Service Terminals, V.28/V.11 DIU

31st January 2020 – DB2, DN2 CU & BPU, G.703 & V.110, DIU, Ethernet I/F, Ring Gen, NDM 19” Subrack, NDA

@YellowsBestLtd satisfies customer product sourcing requirements for current and ‘legacy’ equipment technologies.

Should you wish to read the full ‘ramp-down’ notice and know more about obtaining equipment before it is no longer available, then please get in touch.

Keymile UMUX – Multiservice access solutions

Comprehensive Functionality

The UMUX platform provides carrier-grade reliable multi-service multiplexing and aggregation functions over copper and fibre networks. A variety of voice (POTS, FSX, FSO, ISDN) and data (e.g. G.703, V.11, V,24, V,35) interfaces, SHDSL and Ethernet (including PoE+ and EoS) services are available. 

The modular and flexible housing provided by the UMUX 1500 (8U, 21-slot) and UMUX 1200 (4U, 8-slot) 19” subracks provide the perfect solution for all applications and locations, offering redundant controller and power supplies.

‘Legacy’ telecoms history

The UMUX SDH product portfolio was originally launched 1991 by Ascom, which subsequently became Keymile.

In 2003, by when 70,000 units had been deployed worldwide, the ‘enhanced’ UMUX multiservice access platform was introduced, offering the delivery of ATM, TDM and IP based services from the same platform, with support for IP/Ethernet, ADSL, VoDSL and G.SHDL.

Keymile was sold to ABB in 2017 when the UMUX range was discontinued, and then was acquired in 2019 by DZS. 

Continuing to provide operational service

The UMUX, together with the UNEM network management system and ‘sister’ LINERUNNER and MILEGATE products, continues to provide operational service with various global Operator, Utilities and Transport companies. 

@YellowsBestLtd supports requirements to maintain these networks by supplying various spare part items from refurbished and surplus stocks in perfect working order.  

There follows a list of the main elements that are typically provided, though other items can be provided. Please let us know of any specific requirements you may have. We look forward to being of assistance.

Part CodeUnit typeDescription
A31A1679U1500-CSU1500 Core R2 (DC) for 19″ mounting (incl. Subrack, POSUM, COBUX 128x2Mb/s XC)
A30A0205DATAS-FUData Interface unit.  Multi-Interface V.35, V.24/V.28, X.24/V.11, RS485, Ethernet, 4 ports, all options
A24A3323LOMIF-FU2 Mb/s IF (E1), 8 x G.703 Interfaces
A24A3651COBUX-FUControl Unit Standard,128x2Mb/s XC
A21A2865EXLAN342POTS FxO Interface Unit, 12 ports, complex impedance
A31A7871GECOD371Data IF 64kb/s G.703 codir., 8 interfaces
A24A3338LOMI4-FU2 Mb/s IF (E1), 4 x G.703 Interfaces
A24A7979POSUM306Power supply unit -48VDC 85W
A30A1442SUBH3-FUPOTS FxS  Interface Unit, 30 ports
A31A7873SULIS393ISDN Interface Unit Subscriber side, ISDN BA 2B1Q, 8 interfaces
A23A9927SYNAC-FUSDH Access bridging unit SBUS-PBUS, 8xVC-12; no external IF
A24A1989TUPON-FUOptical Trunk Interface 8Mbit/s 1xopt.(o), 4xel.(e), 1550nm, PBUS access


Nokia ‘Dynanet’ Telecoms – Stock disposal

‘Last chance’ for spares!

The Nokia ‘Dynanet’ family of PDH Transmission telecoms products has served customers well for the last 20+ years, and indeed some networks continue providing good operational service. 

DM2
Dynanet Subtrack

@YellowsBestLtd has supported requirements to maintain these networks by supplying various spare part items from refurbished and surplus stocks in perfectly working order.

However, demand has recently reduced and warehouse space is needed, so now the time has come to recycle / dispose of a large proportion of the remaining equipment. Consequently, there remains a short-term opportunity to obtain any items still required to maintain existing deployed infrastructure, before the products are gone.

Here is a stock list of the main items currently available, though there may be a few additional parts that can be supplied. Hence, please check and if you do have any requirements, please let us know – before it’s too late! We look forward to hearing from you.

Part  NumberDescription
24204TPSO H/W Module
CC 24002DB2 Branching Unit, B2 2×2 Mb/s 75 ohm
CC 24011DB2 2 Mb/s Switching Unit, X2 75 ohm
CC 24101DN2 Interface Unit (IU2) 2×2 Mb/s 75 ohm
CC 24111DN2 Control Unit (CU) 75 ohm
CF 24186DN2 19″ Subrack
CF 24186.09DN2 Subrack 19″, grey-L91 EMC
CG 24170DN2 Bus Power Unit (BPU)
CG 24171Extended DN2 Bus Power Unit (EBPU)
CU 24013Data Interface Unit (DIU) 2M, nx64k: G.703/704, 75 ohm
T30506.0917-slot DYNANET Subrack
T30851.02Subrack Power Adapter (SPA)
T37870.01NDM ACM2 19in 17-slot subrack
T37871.01NDM DN2 19″ 17-Slot Subrack
T37882.01NDM DC Unit (NDUe)
T37882.02NDM DC Unit (NDUe)
T37885.01NDM Ring Generator
T37889.01NDM Backup Unit (NBU)
T65520.01ACL2 RM DC Power Gen
T65580.01ACL2i PF GEN Line Terminal Card
TA 21513Optical Line Terminal Repeater 2-8 M, 1300 nm LED MM/SM
TA 21516Optical Line Terminal Repeater 2-8 M, 1300 nm LASER SM
TC 21101DM34 Mux Card
TC 21301DM8 Multiplex Equipment, 75 ohm
TC 21705Supervisory Substation
TC 21710.01TMS Adapter
TG 21261Ring Generator 25HZ 15W
TU 21122.5Data Interface Unit (DIU) 48..64k V.11 10ch
TU 21124Data Interface Unit (DIU) NX64k V.11/V.35/X.21 2CH
TU 21124.05Data Interface Unit (DIU)
TU 21125Data Interface Unit (DIU) 48..64k with sync, X.21
TU 21205Channel Unit SUB/SUB
TU 21206Channel Unit SUB/SUB
TU 21215Channel Unit SUB/EXCH
TU 21216Channel Unit SUB/EXCH
TU 21234.20Channel Unit E&M/VF-P, 10 CH, 20 E&M CH
TU 21236.10Channel Unit (CU) 8ch E&M/uP: 2xe&m/vf
TU 21255.01Channel Switch, 4 PORT
TV 21640.08Power Interface Adapter DC

Three years milestone

Three years completed; onward in our fourth year!

@YellowsBestLtd has now reached the significant milestone of completing three years of trading; something often useful to be able to state when qualifying for opportunities and registering with business customers.

Our aim continues to be “Keeping Customers Operational”; understanding requirements and fulfilling them by providing a range of management services and solutions, including:

  • consultancy, such as business development planning3_years_services
  • technical support, e.g. day-rate engineering, NMS assistance
  • systems supply, including legacy IT servers / workstations
  • spares for infrastructure, in particular telecoms and CCTV cameras
  • repairs at module and component level, e.g. LED displayboards
  • value recovery through reverse logistics, resale and recycling

As we move forward in year four, we’d very much like to discover what else to provide to our existing Customers, as well as what would be of interest to potential clients. We’re always keen to enhance our range of #business services, increase the #enterprise infrastructure we support and expand our mix of #sustainable solutions we offer for supply and maintenance of new and legacy #technologies and products.

Please get in touch to discuss your challenges; whether you’re implementing new systems or maintaining existing infrastructure to serve your operational business needs. We look forward to hearing from you.