The moisture meter should be fairly accutate to +/- 2% MC. I have a moisure meter I use for my woodworking and that has 2 scales depending on wood species. I have another cheaper moisture meter which was free with a wood burning stove and that corresponds fairly well with my expensive one. The possible issue is the sample that one is measuring, how representative is that of the bulk pile and how representative is the measurement of the log being measured. If you leave a wet piece of wood in the dry at ambient temperature for long enough the MC will eqilibrate at round 15 to 16%. Stacked joinery wood in stick, one can reckons it will reach 15% MC per 25 mm thicknes per year. So 50 mm will take 2 years. One way to check how good the kiln drying is would be to cut into each log and measure it. It is possible the wood drying business has an industrial moisture meter with long prongs that can be driven into the log. I air dry my wood indoors in my redundant cattle sheds and typicallly get down to 16 to 18% before use. At this moisture level i find I can have a fire on several days without dirtying the glass and then what soot is on there wipes off with a damp tissue. I get no tarring.

Posted By: JontiHopefully the kiln is solar powered.

I would predicet not Not predictable enough. What I have gleamed locally is that they burn scrap wood from building sites and anything unsaleable in terms of saleable fire wood logs. Think they can still be getting RHI for running the boilers.
The NI scandal around the RHI eventually brought down the NI power sharing government at Stormont. Cash for ash as it was termed every £1 spent got £1.60 in return. There was also lack of uptake of larger more efficient boiler because more subsidy was available for smaller units.

Posted By: JontiI have found that air dried birch or alder gets down to under 10% after 6 months drying (April to September).

Thats interesting and I am somewhat surprised.Timber as it dries it followes an equilibrium moisture curve (EMC) which its moisture content equilibrates with the RH. It then exhibits a hysterisis curve as it reabsorbs. Your birch and alder will reabsorb moisture as the RH goes up again from the summer months. The topic can be quite complex as different species will exhibit their own nuances.

Thanks I'll ask them to split a log and check moisture levels.