UPS (backup)

Your Actual installation

Pic. 1 shows the default single phase layout of a household with

  • a mainpanel including a PHCN meter for billing
  • two power lines 230V for two independent supply strings ending in
  • a circuit breaker box where several fuses are located transporting the power to the consumers. 

In case PHCN shuts down the supply you suffer a total blackout.

To provide you with power even during blackout there are several technical solutions suitable:

  1. the backup system provides you with accupower for a certain time
  2. the backup with PV system even generates PV-power itself to load the backup

the creme de la creme solution even incorporates an auxiliary generator loading your backup system


The Backup System

In Pic.2 you the structure of a backup system built into your standard single phase installation.

For a sustainable system you need

1. accumulators

the capacity of the accumulators define the power they can supply for a certain time.

2. bidirectional inverter

The bidirectional inverter is the heart of the system. It contains

a. charger

the charger uses PHCN AC power to charge the accumulator with DC. Size of the charger has to fit to the accumulators to provide a quick reloading during PHCN-supply.

b.      automatic switch

within 20 milliseconds after a blackout the automatic switch changes from “charger” to “inverter”. As you can’t realize a timespan of 20ms you will enjoy an uninterrupted power supply.

c. inverter

The inverter provides 230V AC power out of your DC accupack. Now Your backup provides power to the attached string and consumers (blue line).

Size of your system:

A nice thing to have would be enough accupack capacity to run all your consumers during blackout for quite a long time. This is like always a question of the size of your wallet.

These are the basic considerations to define the size for your backup system:

The normal way to design for you a tailormade solution is to divide your consumers into several priorities:

  • “must always have”
  • “like to have” and
  • “not necessary for now”


the consumers itself have to be divided again into

  • larger consumers like a/c’s and washing machines
  • medium consumers like fridges, air blowers, PC’s and TV’s
  • smaller consumers like light, door bell


A combination of your own priorities and the demand of your consumers with priority define the calculation basis for the size of your accupack.

Now you have to decide for how long you need your accupack to supply your house during blackout.

These two values define the final size of your accupack.

The charger has to fit to the size of your accupack. It needs to charge your accus again during PHCN service after a blackout.

This is an example for a proper calculation:

A fully charged accupack with a capacity of 350Ah (amps hours) should be able to power your lights, charger for your mobile phone, the fridge, a TV and an air fan (no a/c) for about 4 – 7 hours.

If your accupack has not been recharged after your last blackout yet, the supply time is shorter, obviously. The capacity of your inverter should be here about 3,000 W.

To increase the lifetime of your system the DC voltage of your accupack should fit to the installed size of accupack and inverter.

Smaller applications run on 12V DC, medium ones on 24V DC; larger and multiple phase installations on 48V DC.

Our team is specialized in supporting you finding the best technical solution for you.

It is important that you connect only the most necessary electrical load to the system in order to achieve a long life of your batteries . Light should be able to feed your system into your rooms , with telephone landline , your charging station for your mobile , your doorbell , the refrigerator , the TV , the computer , and one or two fans . At this size , the inverter should not be less than 3000 watts and the battery does not fall below a minimum capacity of 350 Ah. This allows interruption times of about 4 - 7h . be covered depending on time of day. However, this requires a 100 % filled battery bank. Should the interruption after the other pile , the operation of the connected devices must be restricted in order of preference .

System performance and battery voltage

The larger the inverter in its output , the higher the battery voltage should be.

For systems with a capacity up to 1000 watts you can use a battery voltage of 12 volts without hesitation. For systems of 1000-3000 watts we recommend 24 volt systems. All stronger and multiphase systems should preferably be operated with a system voltage of 48 volts to the power taken from the batteries to keep them in bounds.