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ON-GRID vs OFF-GRID

How does it all work?

There are essentially 3 system types

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  • The 'On-Grid' system (no batteries)

  • The 'Hybrid On-Grid' system (with batteries)

  • The 'Off-Grid' system (only batteries)

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The 'On-Grid' system

(No batteries)

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  •  Solar panels generate power as a result of sunlight shining onto the panels.

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  • The panels are connected to a device called an 'Inverter'.

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  • The 'Inverter' is connected to the house electricity supply (hence the 'On-Grid' terminology)

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  • The 'Inverter' converts the power generated by the panels into the 230V AC we are all familiar with in our homes, and supplies power to the house.

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  • During daylight hours, the power generated by the panels alone can be enough to power our homes.

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  • When the sun goes down in the evening, the panels will stop producing enough power to supply the house on their own, so the 'Inverter' makes an adjustment and adds the extra power needed from the 'Grid' (PEA- Provincial Electricity Authority).

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  • In darkness the panels are not producing any power, so all the power needed by the house will be supplied from the 'Grid'.

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  • The next day, as the sun comes up, the panels will start to generate power again, and the 'Inverter' starts to use this power to supply the house.​​

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  • Once the sun is high enough and the panels are generating enough power, the grid is no longer needed. The 'Inverter' makes the necessary adjustment, and the house is once again powered by the solar panels alone.

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  • Loosely speaking, in Thailand, from 09:00 - 16:00, the solar panels will be generating enough power to supply your home.

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  • It should be noted that on cloudy days, the panels will generate less power, so this should be taken into account when designing the system initially.​​​

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  • It is probably worth repeating here, that the 'On-Grid' system will supply power to your house during daylight hours only.
    In Thailand, this is typically 7 hours, or approximately 1/3rd of the day.
    The other 2/3rds of the day will be supplied by the 'Grid'.

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  • PEA policy approves 'feed-back to the grid' with these 'On-Grid' systems, provided you have PEA registration and PEA approved equipment.

The 'Hybrid On-Grid' system (With batteries)

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This system uses a 'Hybrid Inverter' and works in a similar way to the 'On-Grid' system outlined above.

The difference is, the 'Hybrid Inverter' can charge batteries as well as provide power to your house.

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  • The 'Hybrid Inverter' converts power from the solar panels to 230V AC and supplies power to the house.

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  • The 'Hybrid Inverter' also charges the batteries at the same time as supplying power to the house.

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  • When the sun goes down in the evening, the solar panels will stop producing enough power to supply the house on their own, so the 'Hybrid Inverter' makes an adjustment and adds the extra power needed from the batteries instead of the 'Grid'.

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  • In darkness the panels are not producing any power, so all the power needed by the house will be supplied from the 'batteries'.

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  • The next day, as the sun comes up, the panels will start to generate power again. The 'Hybrid Inverter' starts to use this power from the panels to power the house again, and recharge the batteries ready for the next evening/night.

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  • Only if the batteries 'run out', will the 'Hybrid Inverter' supplement the power needed by the house, from the 'Grid'.

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  • With a correctly designed system, it will be possible to supply the power to your home from the  'Solar Panels' during daylight, and from the batteries during the evening and night-time.

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  • PEA policy DOES NOT approve 'feed-back to the Grid' with these 'Hybrid-On-Grid' systems.

The 'Off-Grid' system

(No Grid....Only batteries)

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Typically, this system would be beneficial to a residence/building in the middle of a field, or

a place where there is no 'Grid' supply nearby.

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This system uses an 'Off-Grid' inverter and batteries.

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  • Solar panels generate power as a result of sunlight shining onto the panels.

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  • This power is converted into 230V AC by the 'Off-Grid Inverter' and supplies power to the building.

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  • The 'Off-Grid Inverter' also charges the batteries.

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  • When the sun goes down in the evening, and the solar panels stop producing enough power, the 'Off-Grid' Inverter will supplement the power needed by the building, from the batteries.

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  • In darkness, all the power needed by the building will be supplied by the 'batteries'.

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  • The next day, as the sun comes up, the panels will start to generate power again, and the 'Off-Grid Inverter' starts to use this power from the panels to power the building again, and recharge the batteries ready for the next evening/night.

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  • If there is a very cloudy day and the batteries aren't fully charged by sundown, there is an option to connect a small 'petrol generator' to the 'Off-Grid Inverter' to help charge the batteries.

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