If the inverters are single phase and ideally have a G98 cert then break the lot into 6 separate systems and sell next spring to max out the sell price. Otherwise its a job lot of likely older and "obsolete" kit

I'd guess that secondhand 3ph inverters are a bit of a niche market?? Panels will always sell at the right price but offloading 150 used panels in one go might only be selling into the trade. If youre able to store the panels I'd imagine you'd make more splitting them into domestic size lots, 3-5 kW. Mounting rails, clamps and roof hooks should sell well on their own.