How to convert existing inverter to a solar inverter?

Solar inverterThe inverter is a popular home appliance used to avoid complete power failure at home & offices. Most homes equipped with inverter battery systems in India. Do you know you can use it with solar panels? with littile tweak.
Small rooftop system is a cost-effective and reliable source of uninterrupted power supply. Rather than buying a new solar inverter you can convert your existing inverter /battery bank to the solar rooftop.
It will be pretty easy and cost-effective solution for users who already have an inverter.

Though normal inverter doesn’t has port /connectors for solar panels, it can be connect with solar panel by few additional components. We need following components to convert the existing inverter into a solar inverter :

  1. Solar panels
  2. Charge controller
  3. Some wirinng(length depends on distance)

1. Solar panels

Please gain some information before buying the solar panels. Solar panels available in a large number of capacities and brands. Though you may easily find some cheap Chinese solar panels in market, Cheap Chinese panel looks perfect by shape and size but most probably under rated. So we recommend to have MNRE approved solar panel.

How to choose solar panel voltage?

Solar panels available with various voltage options. Select one which can easily couple with your existing battery bank. Each MNRE approved panels have a volateg and current rating label on the back of solar panel. The label contains detailed information about solar panels capacity, voltage and current. Do not confuse with 2 types of voltages over there, Voc (open circuit voltage) and Vmp(Voltage at Maximum Power),  select a panels with higher Vmp.

Battery voltage depends on number of batteries connected to system.
– If you have single battery inverter then choose a solar panel with Vmp between 14V to 18V.
– If you have double battery inverter then either choose a solar panel with Vmp between 28V to 37V or 12-volt panels and connect them in series to produce 28 Vmp.
If you are planning to buy solar you can check the data sheet of specific product. Confused where to find data sheets? Well, each solar branded solar panel company have an official website, You can find datasheet easily there.

For the reference please visit Microtek 100W solar panel data sheet .

How to choose suitable solar panel size?

Each solar panel comes with a capacity (wattage) rating, such as 100w, 150w, 200w, 250w etc. It is important to note that current produced by solar panels should not be exceeded to battery safe charging current. Battery has an ideal voltage and current ratings for charging, the ideal charging voltage for a 12volt lead acid battery is 14.5V and ideal charging current is 12A, therefore solar panel charging current must be below 12A for single battery otherwise it may affect the battery life.

Single battery system

Maximum solar panels installed on single battery  inverter system is 300W

  • Solar panel:12V-250W – 1no, 12V-150W – 2no, 12V-100W – 3no,
  • Charge controller: 12V, 20Amps, MPPT
  • Inverter: 600 – 900 VA
  • Battery:150AH Tubular, C10

Double battery system


Maximum solar panels installed on double battery inverter system is 600W

  • Solar panel: 24V-250W – 2no
  • Charge controller: 24V, 20Amps, MPPT
  • Inverter: 1400 – 1800 VA
  • Battery:150AH Tubular, C10 -2no

Charge controller

The charge controller is an electronic device which controls the flow of current between your battery and solar panel. It discontinues the charging once the battery is fully charged, hence prevents the battery from overcharging moreover, prevent the reverse current flow from battery to solar panels at night.

The capacity of charge controller measured in watts. Always make sure to install a charge controller with larger than total solar panels wattage.
For example, if you installed two 100W solar panels than buy a charge controller of 250W. You can opt for a charge controller with LCD display. LCD shows the battery health, voltage and current ratings, these reading are used to monitor the output of solar panels. Charge controllers with LCD display are bit expensive but worth to buy.

Types of solar charge controller

1. PMW charge controller– Most commonly used charge controller.
2. MPPT charge controller– It is advanced charged controller with MPPT technology which increases the efficiency of solar panels up to 30%.
Some of popular solar controllers brands/ manufacturers in India are:

  1. Systeller
  2. Phocos
  3. Sukam
  4. Microteck
  5. Luminous

How to connect solar panels?

The solar panel connections must be done carefully, otherwise, it may damage the whole system. Each solar panel have two terminals, positive (+) and negative (-). In most of the cases you can identify terminals by reading labels on them. If you don’t find any label or mark then use a multi-meter to identify the terminals.
Basically solar panels can be connected in 2 ways:
Connection in series– Positive terminal of one solar panel connects to negative of other. Series connection increase the overall voltage of the circuit.
For example, two 12 volt 6A solar panels connected in series would increase voltage to 24 volt, current will remain same ie 6A.
Connection in parallel– Positive terminal of one solar panel connects to positive and negative to negative. Parallel connection increases the overall current of the circuit.
For example, two 12 volt, 6A solar panels connected in parallel would increase current to 12 A, voltage remain same ie. 12 volt.

Always use red and black color wires for positive and negative terminals respectively.

2 Comments

    • Dear Amit,
      There are 3 ways to utilize the solar power in the current situation.
      1. Put an On/Off switch for the inverter, Switch off the grid supply in the morning and switch it On at night daily.
      2. Put an automatic timer switch, It switches off the grid supply in the morning and switches on at night automatically.
      3. If your budget allows buy a hybrid solar inverter. It will automatically select the Grid or Solar based on availability.

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