RE: Mr Happy it was advertised as so with the following blurb when I enquired (as you can tell I am not an expert, I ordered 2 units ans the other works fine):

 

This decoy has a solar panel located behind the blue lens which is connected to the included rechargeable battery. With daylight the battery charges and is kept topped up. The battery pack when fully charged has a voltage of 4.8v and the LEDs only require a small amount of power above 3v to flash. There is enough capacity in the battery to keep the LEDs flashing for several weeks even in there was no daylight. During winter there is still daylight which will charge the battery so the LEDs will flash. Once fitted you can leave it for several years and it will keep on flashing. The decoy cover is identical to the live siren and will look like you have a real alarm. ADT is probably the best known alarm company in the UK so fitting their decoy will be a great deterrent. Hope that helps. Have a great day and best regards.

Should have bought a Verisure plaque. 

In hindsight, yes!