I own FSFL too, but probably not for much longer. I suspect the root cause is increasing exposure to wholesale power pricing. These prices are in decline - maybe this is one of the by products of renewables: plentiful cheap electricity. Take a look at the principle risks in the annual report - top of the list is the impact of decline in wholesale power pricing.
Existing assets are losing value which is natural (except when their lifespan is mysteriously lengthened), new assets are subsidy free - likely to increase exposure to wholesale prices.
This is likely to reduce NAV, and the share price will follow. Ultimately if cash reduces significantly the dividend will be put at risk. Which may be why we have changes to the investment objective - the dividend used to be linked to inflation, not any more. Take a look at historical versions of the investment objective. A slight but sneaky change.
Not as sneaky as changing the discount rate used to calculate the NAV. The calculation of NAV and the choice of discount rate isn’t properly explained in the reporting. A reduction in the discount rate will push up the NAV, or in this case, cushion the fall.
Their decision to get exposure to batteries may help the above issues as the revenue isn’t linked to power pricing in the same way.
I now view this as a bet on them being able to add to, and churn their assets at a faster rate than they devalue, and than power prices decline. As an investment it probably boils down to whether the dividends offset the likely erosion in capital.