New PV FiTs - Good News?

My short answer is "No". In November I posted results from running the then proposed numbers though my simple model, showing that commentators were right to call "Foul". I think I should point out here that my model fits very well the results I am seeing from my own installation, so I have some confidence that, simple though it is, it does pretty well represent expectations. I have rerun the model on exactly the same example project except that I've used DECC's revised generation tariff of 4.39 p/kWh and their capital cost estimate of £1630/kW. Oh dear! I calculate the NPV at year 20 to be -£1129. Even if I assume that there's no need for an inverter replacement part-way through the project the NPV is still negative at -£516 (tho' the project does break even in year 25). To achieve my previous target of a 10% IRR the capital cost would need to drop to £837/kW, almost down to 50% of DECC's assumption. A more modest 5% IRR would require installation for £1247/kW. I would like to be proved wrong but I fear that there is going to be a nasty down-turn in solar PV installations.