Traditional solar photovoltaic installations, in the main, have to be installed on a single roof facet which is usually the south most facing part of your roof. All the panels used need to be identical which means along with the need for a south facing aspect limits the potential of your roof space. In the UK this means that millions of homes are not suitable for solar power.
To solve this problem SolarEdge came up with an add-on power module (powerbox power optimizer) that can be attached to each panel to give module level control of each panel. This essentially means that different types of panel facing different directions can be joined together and connected to a single inverter. Without this technology the added cost and potential power loss would make the installation cost ineffective.
On the whole photovoltaic solar panels work well under optimal conditions. The problem is that we do not always have optimal conditions which means that the panels are not always performing to their full potential.
One such problem is shading. Panels can be fully or partially shaded which means they are no longer getting direct sunlight. The types of panel used on most domestic installations in the UK work best in direct sunlight rather than indirect ambient light. This means that when they are even just slightly shaded their output falls. To compound this problem as the voltage of the panel falls it affects the entire string of panels and reduces the effectiveness of all the other panels even if they are not in the shade.
As a result of shading the electrical power output of the array can be reduced by as much as a quarter with just partial shading. This is because traditional inverters treat the whole string in the array as if it was a single panel. You could solve this problem by having several inverters but as solar inverters are expensive it wouldn't be a very cost effective solution.
In situations where there is potential shading or where you want to optimise your roof space by installing panels on different facing aspects then a per module power optimizer can make your installation more efficient.
A solar power optimizer maximises the output from each panel so that the inverter can run at optimal efficiency. It is attached to the underside of the panel and can be installed as an add-on or there is an integrated version for panel manufacturers. A single optimizer such as the SolarEdge PowerBox PB250 currently costs around £60 but claims to increase power output by up to 25 percent. This would add about £1,000 to a typical installation in the UK which works out to about 10 percent on the individual solar panel cost. At this price it should in theory pay for itself in as little as 4 or 5 years.
Using a power optimizer allows installations to be done on different facing roof aspects on a house. If you have a south facing aspect but a gable roof which reduces the size of the south facing aspect you could use the gable end of the roof to install panels cost effectively. For people with smaller roofs it means they can make maximum use of the available space by using different sized panels and different roof aspects.
If you have shading caused by tall building or trees that would otherwise severely reduce the performance of a solar array then power optimizers could make the installation financially viable.
As cost s come down solar panel probably have optimizers built in as standard so that a wider range of installation could take place that would previously have not been cost effective. At this point I doubt whether installers of free solar are going to use this technology due to the increased cost where more optimal sites would be chosen first.
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A roof facing as far as a West-South-West (almost West facing) direction or East-South-East (almost East facing) can still potentially generate up to 90 percent of a roof facing South.
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