Panel-level optimisation (PLO)

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PLO uses smart electronics to optimise the power of each panel in a string independently. As explained already, if you have PLO and bird poo is affecting the panel, you only lose half of the pooey panel. The rest operate as normal.

PLO is useful for more than soiled panels.

• It reduces the effects of shade from trees and aerials.
• It optimises the power from solar panels if different panels are facing different directions.
• Even if your panels are all facing the same direction and you have no shade at all, PLO can increase energy yield by about 10%.

This last benefit is due to ‘panel mismatch’. All panels operate at slightly different powers in the same sunlight due to manufacturing tolerances. They will also degrade at different rates. And between rain showers, some solar panels in a string will get dirtier than others. In a string system, this means that they’ll all perform at the power level of the worst panel. PLO solves this.

You should get PLO if you have any shade on your roof, as the effects of shade on a conventional string are so drastic. If your roof space is so precious that you simply want to squeeze every last drop of power from your solar panels, PLO is for you.

If none of the above describes you then you’ll be just fine if you get a regular string-level optimised solar power system.

I’ve started the hardware section by talking about solar panel optimisation because PLO can affect the type of solar inverter or panels you buy.

If you want PLO, there are three options:

• Micro-inverters
• DC optimisers
• Maxim optimisers

Micro-inverters and DC optimisers add about the same to the cost of a string optimised solution – expect to pay about $1,500 extra on a 3 kW install and $2,000 extra on a 5 kW install.

Maxim optimisers are the cheapest way to get PLO. Expect them to only add $750 to $1,000 to a 5 kW installation.

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