Thank you I agree.
Wonder if anyone has experience or knows ,if I can combine these 20 panels into one circuit, even though they are two now.
It's just 3600 Watts total.
I am thinking of several different methods including
- paralleling two mods at a time per Opti
- or stringing all 20 together
I'm wondering how the optimizers would handle the voltage in just one long string of 20.
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Optimizers act analogously to miniature transformers, that can dynamically adjust their buck/boost ratio. Like transformers, they trade voltage and current analogously to what gears do with rotation speed and torque, with the product of voltage and current being roughly equal on both sides of the device. Unlike transformers, they are built for working with DC instead of AC, and do not isolate the two sides.
The raw open circuit voltages of the modules do not add up, like they ordinarily do when modules are directly connected in series. What happens is that the inverter prescribes an operating voltage, and the optimizers work together to solve the algebra problem in order to satisfy Kirchhoff's laws. Current must be the same in all, because they are in series. Voltage comes in proportion to the power that each can produce, and adds up to the voltage set by the inverter. What is "optimized", is that the optimal point of each module (or pair of modules) is tracked separately, and mismatch losses and shading are localized to the individual module, such that "one bad apple" no longer "spoils the whole pot".
The constraint on string sizing is such that DC module power at STC is limited to the amp rating of the optimizers multiplied by the inverter-prescribed operating input voltage. There is also a minimum number of optimizers per string, typically 8, depending on the specific products selected. In the case of the 7.6 kW HD wave inverters, the input voltage is 400V, and typical individual module optimizers are limited to outputting 15A. This means 6000W is the maximum power per string, in this example.
The voltage input range needs to be coordinated with the low temperature Voc for the modules, for your location's ASHRAE low design temperature. Given P320 optimizers limited to 48V input, this may look like it can handle your 72-cell modules, but you need to realize that the Voc has to be adjusted for your design low temperature. It may bleed beyond 48V, thus requiring you to use an optimizer that has a higher input voltage capacity.