Solar PV Supplier Midlands?

[alan_m]

But under-running electronics such as an inverter is likely to improve reliability and longevity. It all depends how well the electronics have been designed and how close to their maximum rating they are being run, especially temperature on a dark roof or loft space during summer with no forced air cooling

[Theo]

I found this one:

1.5 and 2kW versions) that has a 4-input MPPT, so you could run 4 or 8 panels off that, and potentially have multiple inverters rather than optimisers and a separate inverter.

The reason for thinking about this is residential solar is often compromised in some way - shading from trees, non-optimal sun angles, birds pooping on the panels, leaves, etc. So an optimiser or MPPT allows you to get the most out of the site that you have, and if the cost is cheap enough you can just fit more panels even if the placement isn't perfect.

Theo

[Andy Burns]

What do they do, effectively "short out" any panels that are giving low voltage while they are in shade?

[Theo]

MPPT is maximum power-point tracking. MPPT optimisers are essentially a DC-DC converter. The panel has a certain sweet spot it can yield most in terms of I/V characteristics given the current illumination, but it can be different for each panel (shading, panel size, ageing, etc). So the DC-DC pulls the energy at the optimal panel I/V and then outputs a current to match the rest of the string, adjusting its output voltage to control it. This pushes the most energy out of the string into the inverter.

If the panel was completely blacked out it would have no output power and so the voltage out of the optimiser would be 0V and look like a short, but if the illumination was weak it would have some voltage and so still generate some energy.

I don't know if it's all analogue feedback loops to communicate across the string or whether the optimisers communicate. Multi-MPPT inverters have the power electronics inside the inverter, rather than a module on the back of the panel.

One advantage of optimisers on the DC side over AC microinverters is I don't think they need to be G98, since they aren't attached to the mains supply.

Theo