My EPS (like UPS) is not part of the original house wiring, I have on FCU supplying the central heating, and two double sockets supplying the fridge and freezers, and for lighting rely on an emergancy torch to find items to light the house independent of main house lighting.
The battery in the main is to transfer off-peak to peak times, and to smooth out the solar supply so I can use a 3 kW appliance without drawing from the grid, 10% is reserved for power cuts, but 640 watt/hours would not last long, it is hoped we have more than 10% when the power cut happens.
The problem with manually turning over to a generator when one has a power cut, is how do you know when the power has returned?
In the main, a power cut is only a problem with heating and freezers, we can do without cooking, and use torches and candles for light, even heating, I still have an open grate, it has a board to stop drafts, and a spigot to allow the AC to vent through the chimney in summer, saves having a window open, but although I have never lit a fire, it is there should there be an emergancy.
So in the main it is freezers which need a back-up supply. A chest freezer can likely if well stocked last 24 hours without power, however the frost free upright freezer it depends when the last de-frost cycle was as to how long it will last, and also unlike the chest freezer, opening the door to get food would allow rapid heating up of rest of food.
So in the main, it is the freezer that needs emergancy power, and any manual generator will need as the name suggests, some one to manually turn it on.
I found out the hard way, losing 2 freezers full of food, while away from the house looking after my mother, the problem when manual intervention is required. The fault was simple, a RCD had tripped, so this house, the three freezers come from to independent RCD sockets, which only supply the freezers, so very unlikely they will trip, and even more unlikely for both to trip.
I will admit a red indicator lamp to show they are powered up, is not the best option, an emergancy torch would be better, one does not notice a light not lit, better for some thing to light up.
But if I did not already have battery back-up, then the portable battery packs with built in EPS seem to be best option, as they auto cut in with a power cut.
We did when working on the Falklands have a problem with generators failing, which powered to connection to UK, so was a major concern, so a large UPS system with a bank of lead acid batteries was installed in the offices, however by the time it was installed, the generator problem had be resolved, and there were more power cuts due to the UPS failure than generator failure.
This does need considering, I have looked at the plug in battery packs, they have a second use when going out, and by adding a plug in timer, I could charge with off-peak, and use during the day, reducing the load on the existing batteries, so they would last further into the winter evenings. By powering my fridge and freezers from them, AI says "A typical modern 60 cm fridge freezer uses about 0.3 to 0.8 kWh per day (averaging roughly 0.67 kWh per day)." so with three I could use 2 kWh per day, more to the point around 750 watt/hour during the time dusk to 00:30 when off-peak starts, I don't feel the gain is worth the money, so not getting one. However if I did not already have batteries, the situation would change.
Also looked at generators, petrol/TVO would be best option, then it could run on my central heating fuel, but my inverter can be used with either a generator or the grid, not both. With the grid it only uses grid power when batteries are down to 10% but with generator it will start it and run it to recharge batteries, so it is run at most economic rate, for as short of time possible.
It is bad enough watching fuel oil level for heating, without going totally off-grid. And with oil prices, that option is not really a good idea.
So basic point, it is good to look at the options, but in the main, stand-by generators are only for people living out in the country where power cuts are common, from around 1933 to 2008 we have slowly brought more and more homes onto the national grid supply, think the remote village of Abergeirw in Gwynedd, Wales was last on 19 December 2008, it does point to how long it may take to upgrade the grid, but to now look at going off-grid, does seem a bit silly.
