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Inverters, Solar Panels, and Energy Storage: Facts you may not Know (Part 1)

Monday, 06 August 2018


Domestic inverters are typically used for energy storage to be utilized in the event of power outage. The higher the number of batteries you have the higher the storage capacity you achieve.


Fact 1: battery manufacturers promise a battery life of more than five years, and depending on the technology, some even boast of up to ten years. Usage is a key factor in determining how long your batteries will last: the more frequent your batteries discharge fully (i.e. you hear the beeping sound or the inverter shuts down) before recharging, the shorter the life of the batteries.

Reality: Most batteries in Nigeria today hardly offer useful life after four years, it is common to see battery replacement only after two years. Most people are ignorant of the dangers of allowing the batteries to discharge fully during power outages.


Fact 2: After the restoration of power supply, the inverter uses the grid or mains supply to recharge the batteries, and your energy meter registers or records this additional energy requirement as an extra load.

Reality: After power restoration, the charging load seen by your energy meter presents a virtual 24/7 supply in the sense that the energy used during an outage event is recovered from the grid as if you were enjoying grid supply all the time. The higher the battery capacity (i.e. the number of batteries), the bigger the charging load. The older the batteries, the faster it drains during an outage event and the more frequent it requires recharging and hence the more load your energy meter records.  In fact, the continued use of old batteries mimics a 24/7 plus power supply scenario. This is by the virtue of the fact that a considerable percentage of the charging load drawn from the grid in recharging the old batteries is wasted due to decline efficiency of storage and retention.


Fact 3: Depending on the technology of the battery and hence the lifespan of the battery, there is an occasional need to change your batteries over the course of the useful life of the inverter.

Reality: Most inverters used in the country today offer less than four years of useful life, this makes battery replacement a critical cost consideration. The higher the battery capacity, the higher the replacement cost, and this is in addition to the energy costs incurred during the re-charge of the batteries after a power outage event.

The Hidden Costs:

1)       Your monthly energy costs increase due to the charging load from your inverter batteries

2)       There is substantial replacement cost associated with the use of inverters: you need to change your batteries every 2 to 4yrs

Conclusion: Inverters are luxury items, there are considerable, sometimes hidden, costs associated with its usage


Solar Panels:

Solar panels convert energy from the sun into electricity. The size or capacity of the solar panels determines the quantum of energy convertible from the sun. Solar panels also use inverters to store the energy converted from the sun for use during periods the sun is not available.

Fact 1: The technology of the solar panels determines the efficiency with which the panels convert the energy from the sun. The more efficient the technology, the smaller the space requirement and the more expensive.

Reality: most name plate information does not translate to the actual efficiency of the panels. With poor regulation of imports, most solar panels in the market today fall into this category. You are advised to use certified professionals to ensure the quality of work and materials. If you live in a clustered residential environment, there may be a limit to the benefits you can derive from the use of solar panels due to space limitations. The smaller the space available to you to mount these panels, the lower the capacity available for you to use.


Fact 2: On a capacity basis, the cost to acquire a solar panel system is more than ten times that for a petrol generator.

Reality: within the useful life of a solar power system, a petrol generator of equal capacity and of similar usage would have been replaced many times over, and this is inclusive of the fuelling and maintenance cost involved. The minimal maintenance of solar power system and the relatively short lifespan of a petrol generator, to an extent, compensates for the initial high acquisition cost of a solar power system.


Fact 3: Although not a compulsory requirement, batteries for energy storage form an integral part of a solar power system. For most domestic uses, especially in Nigeria, batteries for energy storage are usually incorporated in solar power systems. In this regard, all the issues associated with battery usage for energy storage analysed above remain valid. The only significant difference being that the energy requirement for battery re-charge is not from the grid. This energy is free.

Reality: The major difference between an inverter power system and a solar power system is that the energy needed to recharge the batteries is free as it is drawn from the sun. This is a major financial consideration in determining which system to adopt. An inverter system may seem cheaper at the initial stage but in the long run,

About IWIN

The Independent Energy Watch Initiative (I-WIN), an enterprise of Energy ConServ and the Roundtable for the Growth and Development of Power (RODEP), is an online/web based power sector portal that strives to engage stakeholders and the Nigerian public on topical issues in the power sector.

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