Standby Generator or 15KW Battery UPS and 3kw MD

[gally35]

Is it cost economic to use a EV Car Battery or external for home supply outage, use a backup generator or Solar PV.

To cover a standing load of 0.5kw and cooking Maximum demand of 3kw it seems a small generator or 15Kwh battery might suffice.

What would people suggest as there is no money any more in generating for Grid supply with limits on export it a mug's game to install for lighting, standing load and cooking.

So what is the best economic option to guarantee security of supply as the first priority? All the suppliers I speak to want me to install a solar/Battery system when all I might need to a battery backup by car or standalone? A supplier might be a useful start as well

Thanks for your opinions.

 

[JohnD]

Buy a bottled gas cooker

 

[JohnW2]

To cover a standing load of 0.5kw and cooking Maximum demand of 3kw it seems a small generator or 15Kwh battery might suffice.

I presume you mean the EV battery, since a typical (non-EV) 'car battery' is only about 0.84 kWh

It may not be the most convenient option (one has to start it up, maybe in the cold, wet and dark), but a generator is likely to be the cheapest option. My current standby genny is a 2.5kW one I bought from Lidl several years ago for well under £150, and it still works fine if needed (which is extremely rarely).

In my case, I have no electric cooking (other than a microwave!) and the main reason I got the genny is that it would be very frustrating not to be able to use my gas (LPG) heating because there was an (electricity) power cut - and it obviously also provides light etc.

Kind Regards, John

 

[flameport]

for home supply outage

How often do these outages occur?
Installing a large capacity battery and the associated equipment just for the occasional power cut makes no sense at all.
An installed battery system for a whole house is only remotely credible if most of it's capacity is used every day, which means charging it from solar, or possibly cheap overnight electricity, and then using 90%+ of that stored energy during the following 12-18 hours.

If you want something for occasional use for a few items of equipment, get something like this: https://www.amazon.co.uk/Jackery-Generator-SolarSaga100W-Adventure-Emergency/dp/B09N8KBRRQ

An EV battery is far too big for home use, it would run a typical house for a week on a single charge.

 

[JohnW2]

How often do these outages occur? Installing a large capacity battery and the associated equipment just for the occasional power cut makes no sense at all.
An installed battery system for a whole house is only remotely credible if most of it's capacity is used every day, which means charging it from solar, or possibly cheap overnight electricity, and then using 90%+ of that stored energy during the following 12-18 hours. .... An EV battery is far too big for home use, it would run a typical house for a week on a single charge.

Maybe I'm wrong, but I got the impression that the OP was not talking about acquiring an 'EV battery' for this purpose but, rather, was proposing to use the (charged) battery in his EV as a 'stand-by' energy source - but I may be wrong.

Kind Regards, John

 

[StephenStephen]

I'm confused...

- Do you currently have solar, house batteries, V2G or V2L?
-Are you wanting to have a cast iron guarantee that you'll not be without electricity ever? (Medical need?)
-Are you wanting to save money in the medium or long term?

 

[JohnW2]

I'm confused... - Do you currently have solar, house batteries, V2G or V2L?

The OP seems to be implying that he currently does not have 'anything', since speaks of "what suppliers want him to install".

-Are you wanting to save money in the medium or long term?

It doesn't sound as if his interest is in saving energy costs, but merely wants to have some backup option available should he lose his electricity supply (which, as you imply, would presumably be a very rare event).

Kind Regards, John

 

[ericmark]

Either the outage is short, so does not need a back up. Or it is for an extended time so need to be able to top up the energy supply.

An inverter to supply a freezer needs to be around 2kW to take inrush, and would need around 400 AH at 12 volt.

So likely a 2 kW generator would do a better job.

I have a gas cooker used for camping, plus BBQ, and solid fuel fire, so main concern is the freezers.

 

[StephenStephen]

...or just have a well insulated freezer...

 

[StephenStephen]

I can't remember precisely just now, but our freezer is rated at well over 48 hours without power before defrost...

 

[JohnW2]

An inverter to supply a freezer needs to be around 2kW to take inrush, and would need around 400 AH at 12 volt.

For what it's worth, I can't remember us ever having a power cut of long enough duration for me to even think about the need to use alternative (limited) electricity sources to supply them - I have much higher priorities than that!

So likely a 2 kW generator would do a better job.

As I said, I have a 2.5 kW genny, which has been used in anger very rarely, in many years. However, as I've also said, I use it mainly to enable my gas (LPG) to work (plus lights) and, ass above, have never even thought of using it for a freezer -most are Ok without power for at least 24 hours, more commonly 48h or so (provided not opened).

Kind Regards, John

 

[robinbanks]

An EV battery is far too big for home use, it would run a typical house for a week on a single charge.

We're looking at leveraging it to provide local scale power storage and distribution though, which makes sense to me; EVs being essentially large, mobile power banks. There's a use case for having a small power wall that keeps the fridge going when you're out but you car battery running your hob when you're in

 

[ericmark]

A chest freezer is good for nearly 24 hours, however an upright frost free depends on when it last defrosted.

I had one fail, and had a spair in garage, heard it go bang so knew when it had stopped, gave spair an hour to cool first, stuff in bottom OK, but stuff in top foot had started to defrost.

I would guess failed just at end of defrost cycle, but point is you have less than an hour if happens at wrong time.

New freezer shows temperature when power returned, so you know but clearly don't want to open door, so without that feature, need some thing like ice lollies in top, so you can see if defrosted.

 

[hllns]

An event I was volunteering on used a battery system fronting a generator for load optimisation/backup but like Flameport said they're huge and expensive:

EasyGrid

www.energy-solutions.co.uk

 

[JohnW2]

A chest freezer is good for nearly 24 hours, however an upright frost free depends on when it last defrosted.

A chest freezer should generally be "OK" for a lot more than 24 hours, provided it was not opened and particularly if it was kept as full as possible.

The same is probably also true of upright freezers (again, provided it was not opened and particularly if it was kept as full as possible. so long as it was not a "frost-free" one.

I had one fail, and had a spair in garage, heard it go bang so knew when it had stopped, gave spair an hour to cool first, stuff in bottom OK, but stuff in top foot had started to defrost.

I personally think that there is far too much concern about things 'starting to defrost' (which, initially, will in any event only relate to the very outside of things), particularly if they are foodstuffs we are subsequently going to be cooked, anyway (I'm personally not all that comfortable about freezing things which would be eaten without any cooking after thawing). The only reall issue is one related to practical things, rather than considerations of 'food safety' - such as things like ice cubes and 'ice lollies' being effectively 'destroyed' if they thaw

I suspect that a lot of people may not realise the importance (in terms of the very rare issues we are discussing) of "keeping a freezer as full as possible".

Kind Regards, John