about 30 mins with decent accus (or more if I shifted around various pieces of equipment); although the UPS output isn’t a pure sine wave (its not as rough as a square wave, though a bit odd shaped. I will try and upload a video of it to youtube when I get some spare time I need to hook up the “Vorsicht-Lebensgefahr” mains transformer to my cheapo oscilloscope, and do so without taking a hit from 230V).

To be fair the audio kit works OK with it but I wouldn’t want to run any sound equipment on that sort of power for any length of time.

The UPS units do keep away sags/surges and noise from the boiler firing up (there is only one ring final circuit in my whole house) – and stop hard shutdowns if the mains does cut out. The one on the telephone system generates a log file as well; since UK Power Networks fixed the dodgy 400V service cables to my part of the estate the mains has been fairly reliable, if it does go out its a HV fault (11 000 V side of the substation) and a large bit of town will be off supply. (I’ve already had an apology email from UKPN when the mains went off in town and put ICR-FM off air…)

the phone system, router/network switches and some smalller audio kit is left switched on 24/7 (its less stressful on the PSU circuits to leave it switched on than keep switching it on and off). I did switch to the 100% renewable power from Good Energy last year (which is no more expensive than EDF even after the price rises)

I need to get the roof looked at anyway (as there is some hole that birds were nesting in); so as well as fixing the roof there will be nest boxes put up to replace the hole, CCTV and audio feed from the roof (to watch the birds), and the solar panels put up there; about 800-1000 W. These will charge 4 x 12V accus stored in either a plastic box or outbuilding just outside my house (probably outside the kitchen, as I can get an earthing point there), the -48V DC supply will be split so there is one inverter feed for the fridge/freezer and another DC feed to a pure sinewave inverter that will be used as a clean power feed for all the analogue audio equipment.

that will take some time as I have to get the whole lot cleared through building control (and its probably still covered by Part P) and explain the Council its not a grid tie system, the whole idea is to generate and use the electricity locally rather than feed it back to the grid (as with the usual system during a power cut your solar panels get shut off to stop them trying to back feed the trafo in the substation).