ON / Off grid to use renewables generation in a grid outage?

[holwellcourtfarm]

Our barn fire in September 2017 left us with no grid connection. That got me wondering how we could still make use of the output of our 26 kWp solar scheme. As it was the insureres paid almost £12k for us to be on a generator until we could get reconnected.

Now we are looking at moving and hope to have renewables wherever we go. As we hope to be remote and with the current issues folk are having with power following Storm Arwen I wonder how complicated it is to be able to continue using your generation from renewables on site during a mains failure? It's no problem to install a changeover switch but teh safety relays on PV or wind schemes will not let you draw power unless the grid is live. Can this legally and safely be overcome?

 

[sjt01]

Our barn fire in September 2017 left us with no grid connection. That got me wondering how we could still make use of the output of our 26 kWp solar scheme. As it was the insureres paid almost £12k for us to be on a generator until we could get reconnected.

Now we are looking at moving and hope to have renewables wherever we go. As we hope to be remote and with the current issues folk are having with power following Storm Arwen I wonder how complicated it is to be able to continue using your generation from renewables on site during a mains failure? It's no problem to install a changeover switch but teh safety relays on PV or wind schemes will not let you draw power unless the grid is live. Can this legally and safely be overcome?

Have a look at the Tesla Powerwall. It can act as a buffer between your local generation and the grid, but also act as a giant UPS. If you are on 3 phase then you will need 3 of them. Other battery systems may be able to act in a similar way. Someone I know has made a homebrew system with Victron inverters and lead acid forklift type batteries.

 

[renewablejohn]

Any good supplier should be able to spec an Island system which will work totally independant of the mains supply with the right safeguards in place to allow connection to the grid in normal operation.

 

[Exfarmer]

Any good supplier should be able to spec an Island system which will work totally independant of the mains supply with the right safeguards in place to allow connection to the grid in normal operation.

I understood legally they have to be either or!

 

[Kiwi Pete]

I understood legally they have to be either or!

Not here, so I'm following this thread with interest (considerable interest).

We were looking at installing solar here, the panels and regular (grid-tied) controller came to around $7500, and approx. double that for a battery bank and suitable controller package

For all the electricity we "have to" use during an outage, I'm looking at alternatives to battery banks

 

[holwellcourtfarm]

Not here, so I'm following this thread with interest (considerable interest).

We were looking at installing solar here, the panels and regular (grid-tied) controller came to around $7500, and approx. double that for a battery bank and suitable controller.

For all the electricity we "have to" use during an outage, I'm looking at alternatives to battery banks

This is the output from our theoretically 26 kWp solar PV scheme (108 panels) this week (early winter). Spot the dull days!

Hours of generation are quite limited here this close to the shortest day.

Still be useful in a power cut to keep the freezer cold and the underfloor heating warm though if we could use it.

This compares the last 4 years:

 

[Kiwi Pete]

We are in a similar situation re. bright sunshine hours, where Stewart is has about 2600 and we get around 1200

the only reason we didn't go ahead yet, is that energy price is rising slower than the price of installing solar is dropping, so I just shifted it forward and put my money into a technosystem instead.. but we will get there

Little point pouring all that energy into the grid and still being in the dark when a tree takes the grid out, however just enough to give a bit of a reserve is a lot cheaper than being "totally off grid"
I'm thinking a tankful of water 33m above the house will actually provide enough energy to keep us going for a while, with better safety than having a battery bank near the house.. and when battery tech improves, well we have 33,000 litres of water on the ready

 

[renewablejohn]

I understood legally they have to be either or!

Thats totally wrong. Yes you have to switch between the two but how do you think back up generators work such as hospitals or CHP plant.

 

[Exfarmer]

Thats totally wrong. Yes you have to switch between the two but how do you think back up generators work such as hospitals or CHP plant.

totally different, they are set up to deliver power to roughly match the grid. Inverters do not chuck out power like that, so it cannot be a matter of just changing over a switch. You should not even try to run panels alongside Generators

 

[nonemouse]

totally different, they are set up to deliver power to roughly match the grid. Inverters do not chuck out power like that, so it cannot be a matter of just changing over a switch. You should not even try to run panels alongside Generators

Why? I have had no problems running panels and generator together! Just switch off panels use change over switch isolator, set generator running and turn panels back on - just make sure only have enough panels on to provide approx 1/2 of base load

 

[e3120]

I am quite surprised that a generator can provide a 'good' enough grid to pass the g59/83(?) standards on the inverter.

It must be a decent generator.

 

[Exfarmer]

Why? I have had no problems running panels and generator together! Just switch off panels use change over switch isolator, set generator running and turn panels back on - just make sure only have enough panels on to provide approx 1/2 of base load

I have been told they would blow the generator apart if they produce too much power when the load is small
I am looking at a 110K array

 

[Hampton]

Have a look at the Tesla Powerwall. It can act as a buffer between your local generation and the grid, but also act as a giant UPS. If you are on 3 phase then you will need 3 of them. Other battery systems may be able to act in a similar way. Someone I know has made a homebrew system with Victron inverters and lead acid forklift type batteries.

I have a feeling that Tesla use someone else’s batteries etc but package it and brand it well

 

[Exfarmer]

I am quite surprised that a generator can provide a 'good' enough grid to pass the g59/83(?) standards on the inverter.

It must be a decent generator.

to be honest I dont think it would, but we have informed the site they must disconnect before firing up. It is a site which has chickens and is remote so get frequent cuts

 

[Will0]

Have a look at the Tesla Powerwall. It can act as a buffer between your local generation and the grid, but also act as a giant UPS. If you are on 3 phase then you will need 3 of them. Other battery systems may be able to act in a similar way. Someone I know has made a homebrew system with Victron inverters and lead acid forklift type batteries.

It’s a good system, but I don’t think battery backup is supported on 3 phase. Only 1 battery can function as backup for a chosen phase. You then end up trying to put too much on the backup phase, and run into balancing problems!

 

[renewablejohn]

Why? I have had no problems running panels and generator together! Just switch off panels use change over switch isolator, set generator running and turn panels back on - just make sure only have enough panels on to provide approx 1/2 of base load

I quite agree but then I am not a sparky and I leave such things to the experts. I hate electric as its so easy to be killed by it. Needless to say I treat my two girls with the utmost respect.

 

[wanton dwarf]

Have a look at the Tesla Powerwall. It can act as a buffer between your local generation and the grid, but also act as a giant UPS. If you are on 3 phase then you will need 3 of them. Other battery systems may be able to act in a similar way. Someone I know has made a homebrew system with Victron inverters and lead acid forklift type batteries.

I'm thinking similar, using the backup facilites of a Battery Pack to automatically continue using power from the solar panels whilst off grid - with auto swtiching in the battery pack.

Solar Battery Storage: Everything You Need to Know

Solar batteries let you store electricity for use at a later date. This is everything you need to know about them.

www.solarguide.co.uk

At the time of writing, we were only able to find 3 battery systems available in the UK that will keep the lights on during a power cut. The Tesla Powerwall 2.0 with the Back-up Gateway. This updated version of the Powerwall 2.0 comes with a separate unit which looks like a smaller version of the battery itself and completely islands your home in the event of a power cut. The second and much cheaper option is the PureStorage battery system from PureDrive. Finally, the Samsung SDI can also provide emergency power during an outage. Always check with the manufacturer ahead of the installation as power-cut back-up may not be fitted as standard.

 

[holwellcourtfarm]

Going throughout figures earlier today (for a carbon footprinting exercise) in the last 12 months we have drawn 2770 kWh from the grid (for the house and farm) and exported 9868 kWh (admittedly under deemed export) from our 108 panel system. On the face of it we could be self sufficient.

Whether that would still work moving in rural Scotland instead of North Londonshire I'm not sure yet. We'd probably aim to have a modest wind turbine as well. Ideally I'd love hydro but it'd depend what we end up buying.

A suitable UPS capable battery system would be a lovely extra for whatever we fitted. Eventually I'm sure we'll run an EV which could also charge from it.

 

[wanton dwarf]

Still going to need a generator ?

Are you going to use wood as a heating source or Heat Pump ?

What KW size are you thinking of getting and have an idea of model ?

 

[holwellcourtfarm]

Still going to need a generator ?

Are you going to use wood as a heating source or Heat Pump ?

What KW size are you thinking of getting and have an idea of model ?

All up for thought until we get to offer on a specific farm.....

Just trying to scope out general ideas at present.