The Ball Park Figure Mistake in an Inverter System Setup

The Ball Park Figure Mistake in an Inverter System Setup

By Bruno

Can you give me the ballpark figure of the cost to have an inverter system, with or without solar panels that can power a 2-bedroom or 3-bedroom flat? Can you give me the number of solar panels for xKVA inverter?

These are the most common questions we often get asked by people, clients, and companies when they learn that Right Click Technologies designs and install inverters and solar systems for homes and companies. Most inexperienced or unprofessional alternative energy installers will immediately start to spew out figures without taking other factors into consideration before putting a number out. One such consideration is that the number of bedrooms in a house is not directly or indirectly proportional to the load in the house. A one-bedroom apartment can have equipment with loads that are more than a five or ten-bedroom apartment.  Therefore, giving a ballpark figure with respect to the number of bedrooms is the first mistake that would spell doom for a project that has not yet commenced.

Other factors to consider include – what will be powered, power consumption of desired appliances/loads, the load duty cycle (if applicable), surge rating of the loads, available charging sources, choice of components, the desired life span of the system especially the batteries, and the brand of choice. Detailed explanations are provided below.

What Would be Powered?


The fewer the load, the lower the system’s cost. When discussing with potential clients, their first statement is often to add one to two air conditioning units (AC) to their request but we often advise them against doing this as it will increase the cost of the inverter system astronomically. A system designed to exclude an AC unit can cost as low as NGN300,000 while adding just one 1.5HP inverter AC can increase the cost to NGN2.5 million and more.

Load Power Consumption:

This merely refers to the amount of electricity an appliance consumes while on. The lower the load, the lower the cost of the entire inverter system, and vice versa. Therefore, we encourage homes and businesses that want to install inverter systems to ensure that the appliances that will be connected to the system have low energy. Typically, devices with Energy Star ratings are best buys.  For instance, if you want to have your TV connected to the system and you have an old cathode ray tube (CRT) television that consumes 120W, it will be wise to replace that with an LED television that consumes 30W to 50W. A small inverter can be used to power the LED TV but that same inverter may not carry the CRT TV. When purchasing a refrigerator, emphasis must be placed on the energy rating of the product, the higher the rating, the lower the energy consumption, and therefore, better. Typically, older refrigerators are not as energy efficient as most newer products.

Load Duty Cycle


This is the state of an appliance automatically turning itself off or on according to the design. A typical example of loads with duty cycles are refrigerators and air conditioners. When the ambient environment is cold (like during harmattan), they are off for about 60% of the time (and on, 40% of the time) but when the weather is hot, they are on for about 70% -87% of the time. This has a direct impact on the entire system because the batteries are drained less during harmattan but more, during hot weather.

Furthermore, regardless of weather, a refrigerator/AC on its lowest settings consume less power than when on the highest setting.

Surge Rating of the Loads

A CRT TV may have a surge rating that is 3 times its nominal power, so a 120W CRT TV can have a surge rating of 360W or higher whereas an LED TV has no surge. The same applies to certain brands of refrigerators, air conditioners, borehole pumps, etc. This affects the choice of components like an inverter that powers appliances with high surge ratings will cost more.

Available Charging Sources

The inverter batteries must be charged regularly and adequately otherwise they will be depleted quickly and will ultimately result in their premature failure. What options are available for charging the inverter batteries – solar panels; PHCN or generator or both? Each has its own cost and consideration. One of the best options is just to add solar panels to the inverter system so that the batteries will be charged daily. Obviously, it will cost more to add solar panels to the entire setup.

Choice of Components

Here, the type of product to use has a direct impact on pricing. For instance, a pure sine wave inverter is at least, double the price of a square wave inverter of the same rating. An MPPT charge controller is at least 4 times the price of a PWM charger controller. In the examples here, these more expensive product types are actually better; it is like comparing carrying logs of wood on a trailer versus a pickup truck. The trailer is more expensive.

Battery Life Span Expectancy

The weakest link in any inverter system is the battery(ies) as they can die within 6 months or last as long as 20 years. The most common inverter batteries – the lead-acid type – have a lifespan of up to 4 years while the more expensive ones – Lithium-ion type – can last up to 25 years.

In conclusion, when deciding to use an inverter system, it is advisable to start off by ensuring that you contact a professional and you ensure that the installer carries out accurate load measurements and also future-proof your load requirements.  Also, switch off all loads when not in use. This attitudinal change will go a long way in helping your appliances and inverter system to last long.

In addition, by carefully reducing the load to be powered to the barest minimum, and to research the various brands in the market to decide on the battery and brand of choice. The cheapest 3KVA inverter system with two 12V 200A batteries can be as low as NGN300,000 naira and can go as high as 3.5 million Naira. The onus lies on the designer, discussing with the clients and working within his/her budgets and needs.


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