For the Latest Solar related Articles:
UPS:
Q1: What is the difference between a UPS and an Inverter?
A1: A UPS will filter and clean up mains power that comes in from the utility like City Power and will provide backup power from a battery bank, should that mains supply fall away due to a power failure. An Inverter on the other hand will also provide you with backup power when mains fails, but it is not designed to clean up dirty power like a UPS does, in order to protect sensitive equipment like servers and medical equipment. Both UPS and Inverters create AC Power from a DC source (battery bank), but only UPS's protect their loads from dirty mains.
Some Inverters have a UPS function or setting, this merely means that if the incoming mains voltage is above or below a certain setpoint which could cause damage to the load, the inverter will ignore mains and switch to batteries until such time that the voltages fall back within those pre-programmed parameters.
Q2: What is the difference between a pure Sinewave and a Modified sinewave unit?
A2: A modified sinewave unit is cheaper to manufacture and is not suitable for certain appliances, such as those with inductive loads like microwaves, air-compressors, pumps etc. So choose your system to match the application. Most UPSs in excess of 2kW are usually pure sinewave anyway.
Q3: How deeply should one cycle a UPS battery?
A3: Because power-outs only occur spasmodically (we hope!), the usual battery sold for a UPS application will give you around 250-400 cycles - depending upon the ambient temperature that they are in as well as the quality of the charger in the UPS. Most UPS batteries are cycled down to 70-80% as a rule. The UPS will then shut down before damaging the battery from excessive discharging.
Q4: Can my UPS be employed with solar panels?
A4: UPSs are basically not designed around solar applications – even though some manufacturers would have you believe they are adaptable for solar use. If you have aspirations to ‘go solar’ one day, then it is better to start with a proper solar Inverter-Charger – a bit more expensive, but at least better suited to the job.
Q5: When is it better to use solar for back-up, rather than a UPS?
A5: If you are running a business, then because you are using your power mostly during the day, it makes sense to go solar and at least reduce your electricity bills on a monthly basis. To cater for unscheduled power outages, especially during non working hours; you would need a bigger battery bank which adds to the cost of the system. If the appliances are kept to a minimum (security and convenience items), then it will limit the overall reserve requirement. Usual back-up periods are in the 2-5 hour category as a rule.
Q6: What is the greatest amount of batteries I can use in a bank?
A6: The limitation for any battery bank linked to any UPS is the ability of the charger to cater for the amperage required. A charger should at least be able to put in 10% of the total rating of the UPS battery bank in order to be really effective and to ensure that the batteries are replenished in a shorter period of time, should there be another mains failure in short succession.
Q7: Should I use a lower or higher voltage system?
A7: As a general rule: the higher the amperage the less the losses. However, when going for higher amperage systems remember that you would need to add more, say 12V, batteries, then a lower voltage system where you would be able to add one at a time to increase your reserve.
Q8: Transformer based or Transformerless High Frequency UPS?
A8: If your application for a UPS is in an area where industrial machinery and processes are on the same phases as the sensative equipment that you are needing to protect, then a Galvanically wound transformer based UPS is the machine to use. Areas like business parks where power is stable and no heavy machinery on the same line, a transformerless high frequency UPS is more practical and cost effective.