Portable battery packs, are they worth having, and how to use?

[ericmark]

I have had one for years, but the 300 watt inverter built in, is very different to the modern units. At £400 not cheap

but it will power a lot more, it would, I think power a kettle

as shown (750 watts) however, it may also have some uses at home as well, like transferring off-peak to peak times.

EPS: Emergency Power System.
Once you have connected the mains and the AC input port of the product via the AC charger cable, you can use the AC output port of the product to power your unit (at this point the AC power comes from the mains, not the battery of the product). In the event of a sudden loss of mains power, the product can automatically switch to battery mode within 20ms.

so add a smart socket, and one can charge it off-peak, and once the smart socket turns off, all will be powered from the battery.

I found the manual here seems there are loads of options, including adding with direct connection of a 100W or 200W solar panel. So all in all seems a reasonable unit.

But there are 100s of these units, and to read every user manual to find which is best, would be a long job. I looked at another type here

slight differences like 50 or 60 Hz, second battery, etc. But very similar. I likely used the wrong google phrase (balcony solar inverter/battery pack) I had expected to find grid tie devices, but having solar panels on the balcony does not need a grid tie inverter, that's a completely different function.

I am a little short in winter of battery capacity, and my thoughts were, if I could shed some of the load to a portable battery, rather than fixed, it would have a second use in the summer. I looked at a 287 litre chest freezer and noted Annual Energy Consumption Kwh : 285. So working from that it needs 620 watt/hours for 19 hours a day (peak time and off-peak direct) So I have three freezers in the same area, so nearly 2 kWh used just for freezers, so it would not be much of a job to have a 2 kWh battery pack for just freezers, which would extend the time the main battery will last in the winter, a small unit just outside and it would not even take up room in the kitchen. At the moment just a thought. Started by reading about grid tie units used for balcony solar, but no real need for balcony solar with grid tie, one of these units will extend my existing battery life in winter quite well.

So have I missed anything? Has anyone already done this? So many times on reflection I realise my idea is daft, if not, why are not 100s of other people doing the same, so what have I missed?

 

[Wayners]

Just my thoughts.

Plug-in solar panels often called balcony solar has become popular in Germany and uk government are looking at them for UK DIY market.
You install yourself.
Plug in your mains.
They also come with battery packs I think?
For emergency power an inverter is cheap enough and you can use your car as a generator to power 240v appliances.
As for your question.
I've seen these packs but I can't think of a use for it.
You mentioned outside. Battery pack needs to be room temperature as if it gets cold the power drops.

 

[Ragnar_AT]

Most balcony kits only have grid-tie inverters and don’t come with batteries I think, the ones with batteries are more expensive.

 

[ericmark]

The balcony grid tied solar, would clearly generate revenue, but not sure if enough to be really worthwhile? And as yet not permitted, so was more looking at the battery, as mine are not big enough in winter, so a third battery will help in winter.

The debate is fixed or portable, the fixed, also fixed size of 3.2 kWh on my system, and around £1200, but the portable one can select a smaller model, likely better as lighter.

I looked at base load, and considered what causes the base load, and in the main it seems the freezer account for most of the base load. I have three in a block together, including the central heating, they are all powered from the existing batteries, a pair of double sockets in the kitchen, with a junction box outside, so splitting the supply into a plug and socket, would allow a battery pack to be inserted, and a simple timer could turn off the supply so forcing it to go into UPS mode, and removing some load from the main batteries, those extending how long the main batteries last.

Cheaper due to being smaller, so kWh to the £ no real gain, but they offer as secondary use in summer. The answers from @Wayners and @Ragnar_AT but assume talking about grid tie, I was not really talking about grid tie. None of the units shown are grid tie. The new units will allow solar panels, and I had considered installing a part roof over the balcony to hold solar panels, I looked at the balcony railings,

and not sure if the fixing are good enough to counter wind resistance on the solar panels, so safer not to use to hang solar panels. On the wall above the living room window would catch the morning sun, but the time of the year when I need the extra, don't get much morning sun, the hill opposite means it is nearly midday in winter when we see the sun, yes I know it is light which generates power, but the solar would be so low in winter, and in summer the existing solar produces enough. At the moment exporting 4.7 kW, at 11:20 UTC (12:20 BST) I have already exported 3.2 kWh. I do not really need extra solar, but extra battery capacity may help.

It was the plug-in grid-tie which got me thinking about a portable rather than static battery, I looked at the plug-in grid-tie, and the problem ignoring the law, is to get it to discharge only when required. OK for me with a MPAN export number, I would get paid, but to set it to export any fixed amount, is rather hit-and-miss. And once you look at some energy meter and CT coils, it is no longer really plug and play. So I see very little benefit with plug and pray solar panels, I have already found, without a battery, solar panels don't really help much.

They may help the grid system? With some extra power in daylight, but yesterday solar was 7 am to 7:30 pm, but with the battery, no grid power used 5:30 am until 0:30 am the next day. So the battery reduces cost as much as the solar, they compliment each other. Having solar without a battery is like having a cart without a house.

 

[Wayners]

For those who are interested.
Few months these plug in solar panels should be legal

Government to make 'plug-in solar' available within months

'Plug-in' solar panels to be in shops within months, offering households chance to significantly cut energy bills.

www.gov.uk

 

[ericmark]

For those who are interested.
Few months these plug in solar panels should be legal

Government to make 'plug-in solar' available within months

'Plug-in' solar panels to be in shops within months, offering households chance to significantly cut energy bills.

www.gov.uk

This is what started the discussion on small solar panels. The point to remember in Germany where this is popular, they have a much larger rented sector to us, and so being able to move solar panels home to home is far more important.

In the main they have 16 amp sockets on radials, so the circuits are shorter to our ring finals, and far less change they can be overloaded.

There are problems, clearly one does not want to export power not used, but the government would not mind if you give away solar power, but if one has bought a solar array clearly one wants to get money back for energy exported. So there are two methods, one is a second MPAN number, so one is paid for solar, or a battery, but then looking at quantity and control methods, a battery powered CT coil used with iboost+ units to allow solar to be used to heat domestic hot water, do not cut in until 100 watts is being exported. This is not really a problem with 6 kW of solar panels, but with only 800 watt, any device which switches after 100 watt is not going to use a reasonable percentage of the total.

So the big question is why grid tie? Can panels or batteries be used without grid tie? The answer seems yes, and this was what I was looking at, and how it can or can't help.

Much it seems depends on what the home already has. If a home has storage heaters, and so peak and off-peak already, so no question as to if charging a battery overnight and using it during the day, is going to save money. But if not already using an off-peak supply, the question is how much must be moved night to day to break even.

The smart meter is useless to work out what is being used in my case, and the consumption I only have because I already have solar.