£3k for 5kwh of batteries seems a little steep. The inverter will probably work with a range of batteries. The smart is generally in the inverter, so the batteries don't really matter.

Get the iboost put in at the same time, you'll save some cash as it's a simple installation and if they are doing the batteries why not. Just make sure it's set-up so the order of priority goes, house, batteries, hot water then grid.

Thanks @batalto - that's really helpful including the order of priority.

With batteries - I did find 2 that can supply some energy Tesla's pwoerwall without the grid & the UK made pure drive- though I'm struggling to find many fitting these - not sure if it's new ora reflection of the technology ( or marketing to installers).

I noted previous discussions on here about challenges of working off-grid eg not overloading the battery- how to manage/isolate circuits etc.

I was looking for something that could keep laptops/kettle going in case of a short (24hour) power outage.

One of the challenges of working at home perhaps how to manage without power!

@alex you get get EPS switches, but you'll need a new consumer board with that EPS attached to it so the specific loads can be isolated. It's simple enough to do, but retrofit might be expensive. However if you're doing solar and batteries you could easily do it at the same time for not much money - provided you know your current circuits!!

@batalto- thanks very much. Sounds like I need a fitter/electrician who has done the isolation before. Really helpful in my coversations  finding an an installer

We're looking at an off grid system that can charge via PV and it's turning out to be ridiculously complicated. It's easy enough to put a battery system that runs off grid, but it can recharge via PV which is pointless. Admittedly, I've only started looking at this, but so far there's no easy way around it. Even the Powerwall 2 won't recharge via PV in the event of a power outage. 

Posted by: @editor

We're looking at an off grid system that can charge via PV and it's turning out to be ridiculously complicated. It's easy enough to put a battery system that runs off grid, but it can recharge via PV which is pointless. Admittedly, I've only started looking at this, but so far there's no easy way around it. Even the Powerwall 2 won't recharge via PV in the event of a power outage. 

Hi Mars,

The German company SMA produce a system that would appear to meet the requirements. I have not delved into the details fully yet, but their Sunny Backup system appears to meet what I think are your requirements.

I have attached a document with some details, and I would suggest that you have a look at their website.

Posted by: @alex

Thanks @batalto - that's really helpful including the order of priority.

With batteries - I did find 2 that can supply some energy Tesla's pwoerwall without the grid & the UK made pure drive- though I'm struggling to find many fitting these - not sure if it's new ora reflection of the technology ( or marketing to installers).

I noted previous discussions on here about challenges of working off-grid eg not overloading the battery- how to manage/isolate circuits etc.

I was looking for something that could keep laptops/kettle going in case of a short (24hour) power outage.

One of the challenges of working at home perhaps how to manage without power!

Hi Alex,

Important industrial control and computer systems will often incorporate an Uninterruptible Power Supply (UPS), to safeguard against loss of the mains power supply. It would be possible to keep a computer and router working during a power cut, for a certain period of time, with such a system.

If you need to supply power to your whole house during a power cut then the German company SMA can provide such a system. I have attached a copy of one of their documents, but would suggest that you have a look at their website.

@editor you need an off-grid setup with grid capabilities e.g. a secondary power source i.e. the grid or a generator. That should work. The issue is going to be that your system wasn't installed that way in the first place, so there is probably a load of rework needed.

Thanks @Derek M - UPS does look like a good option for short term use for 1-2 laptops - looks like it could last a  hour or two- thanks for the idea. 

SMA sunny boy looks really interesting for switching to off-grid use when required for domestic PV. As with all these more interesting options- it's finding a trusted installer with the experience to do it that seems a challenge. I've contacted the company - so will see. 

I've also considered a stand alone system eg by sunshine solar - one of the companies reasonable rated by ethical consumer. I've seen people using the off-grid solar kits - eg 330w/24v/1kw storage kit- for Sheds/camper vans/garden offices - so it could work for laptops (with the right weather of course!). 

That may just keep the domestic installation simple. It's been challenging enough to get quotes so far without introducing unfamiliar components systems

@Mars good luck with your off grid plans. & thanks for your blog -  it's been really helpful reading about your experiences. 

Posted by: @alex

Thanks @Derek M - UPS does look like a good option for short term use for 1-2 laptops - looks like it could last a  hour or two- thanks for the idea. 

SMA sunny boy looks really interesting for switching to off-grid use when required for domestic PV. As with all these more interesting options- it's finding a trusted installer with the experience to do it that seems a challenge. I've contacted the company - so will see. 

I've also considered a stand alone system eg by sunshine solar - one of the companies reasonable rated by ethical consumer. I've seen people using the off-grid solar kits - eg 330w/24v/1kw storage kit- for Sheds/camper vans/garden offices - so it could work for laptops (with the right weather of course!). 

That may just keep the domestic installation simple. It's been challenging enough to get quotes so far without introducing unfamiliar components systems

@Mars good luck with your off grid plans. & thanks for your blog -  it's been really helpful reading about your experiences. 

Hi Alex,

I have recently ordered a 1500VA, 900W output, UPS from the UPS Centre, for the princely sum of £108. The primary reason is to help smooth out the power supply to my A2A ASHP, which I operate when there is sufficient output power from my solar PV system.

Let me explain. Last year I installed an A2A ASHP, to better utilise the electrical energy produced by our solar PV system, and in so doing to help reduce our gas consumption. The major problem is that the output from the solar PV can vary quite considerably, just a short while ago today the solar PV output dropped from 2800W to 300W in less than one minute. So within a matter of minutes, my system can go from having ample solar  power to supply not only our home heating, but also hot water, to requiring energy from the grid just to run the heat pump. Although I have an Immersun diverter unit, which performs an excellent job of utilising any excess solar power, to provide hot water via the immersion heater, and also supplement home heating via a convection heater, it would not be possible to use it to power the heat pump, which requires a more consistent power supply. My plan is therefore to provide solar power to the UPS via the diverter unit, the output of the UPS would in turn power the heat pump. The heat pump should therefore receive a  consistent power supply, even when a pesky cloud should obscure the Sun, and also provide additional heating capability later in the day when the solar PV output starts to reduce.

For your particular home office requirement, the UPS described above could possibly provide sufficient power for 10 to 12 hours of operation.

I am now eagerly awaiting the arrival of the UPS, so will provide further details once i get my design up an running.

@derek-m what's the total capacity of that ups? How many Wh?