Solar in a blackout

tails_naf · 03-10-2021 11:10pm #1

In theory those of us with solar could have some power in a blackout - but the current installs (with grants) all have an auto-cut-off when the grid is out that disconnects the solar panels from the inverter.

Some inverters (e.g. solis) have a secondary output that can run when the grid is out, but as the panels are disconnected this would only run until the battery is drained.

So in a blackout, with the sun beating down, we're going to be SOL (pardon the pun).

I was thinking of installing a grid isolation switch that would allow me to keep running - by basically shorting the secondary output to the primary output when the grid isolation switch is thrown (i.e. double pole switch - one side grid, the other side secondary output). Would this work, and allow the solar to keep running? If not, is there an alternative ?

graememk · 03-10-2021 11:36pm

You can get a generator switch put in before your consumer unit - or a sub board with a few essential circuits.

On the sub board you could have some plugs, lights enabled & a supply to the fireman's switch.

Reason I'm suggesting a sub board, is that in chatting to my installer the inverters don't like/your not meant to feed the inverter it's own supply as if it's the grid.

bullit_dodger · 04-10-2021 1:59am

https://www.boards.ie/discussion/2058211555/solar-in-a-blackout

I'm not an electrician, but it sounds like that probably wouldn't (shouldn't?) work. The whole thing about the inverter is that it pumps out a higher voltage than what it detects as the grid. So it would use it's voltage over the grids. So if the grid was reading 220v, the inverter would do 225v or something. If you feed it it's own supply, wouldn't that just create a circular feedback loop? Raising the voltage until it goes out of tolerance? (230v +/- 10%) I guess you could lower it (the voltage), but really, there are probably better solutions. Dedicated UPS boxes and the like.

However, using your backup 3 pin outlet on the inverter, why not just run a 10m extension cord off it and plug in the telly or whatever you want into it. If there was a blackout, it probably would only be for 2-3 hrs max, no?

Victor · 04-10-2021 2:56am

There are two main blackout scenarios at the moment.

A localised blackout due to network damage. This is most likely in stormy weather, nearby construction works or network maintenance. Wind, but not so much solar.
Insufficient supply in the network. This is most likely mid-winter, in cold weather, between the hours of 5-8pm. This would mean no wind and no solar.

Managing you demand generally (insulation, heat storage, batteries, deciding what usage is important) and at such times (batteries, deciding what usage is important) is probably the most important thing you can do.

irishchris · 04-10-2021 8:16am

Several blackouts here so far this year mostly so far in the summer lasting from 1-5/6 hours. Solar has been a blessing in this time.

I have no fireman's switch on the panels and instead just a DC isolator in case of issues. Fitted a generator switch beside consumer unit and in event of outage just click the generator switch and house runs perfectly off both batteries and solar generation whilst keeping batteries topped up. I also turn the AC switch off at the inverter so it is not receiving its own power back

tails_naf · 04-10-2021 8:24am

https://www.boards.ie/discussion/comment/117973106#Comment_117973106

Good to see it can work, and good idea for turning off the primary supply to the inverter while the secondary is driving the full fuse board. So it sounds like we need to

1) isolate the grid from main fuse board

2) isolate the inverter primary output from the fuse board

3) switch the secondary output to drive the fuse board. This allows it run all loads, up to the power limit of the secondary output which is about 3kw

One item, I'd you don't have a fireman switch, do you rely on your inverter primary output shutting off in the event of an outage and you are not at home to switch off the mains?

irishchris · 04-10-2021 8:33am

Yes all approved inverters in Ireland from what I'm aware have anti islanding so designed to shut down in event of grid outage

tails_naf · 04-10-2021 9:11am

https://www.boards.ie/discussion/comment/117973137#Comment_117973137

Shame the grant requires the fireman switch so, seems unecessary, and will lockout the system if the battery goes low overnight it won't have enough juice to keep it open, so will have to remove or isolate that also.

irishchris · 04-10-2021 2:49pm

I suppose it's there to isolate in case of house fire the panels but in my case is in ground mount outside and easily reachable. But agree that surely one of the most important parts of having solar is that you will have continuous power as long as the weather plays ball. But to see a sunny day outside and house with no power during a grid outage is just wrong imo

Manic Moran · 04-10-2021 2:57pm

We've been chewing on the same problem. A battery for the solar system (eg a Tesla Powerwall or the like) makes zero financial sense for us, its only utility would be for power cuts, so we don't have one.

It narrowed down to two options. One was an external generator (running on natural gas or propane), which is a third the cost of system battery. Again, though, long power cuts are rare enough I'm not sure it's worth the cash.

What I ended up doing was concluding that we didn't need to run the whole house. All we needed to do was keep the refrigerators cold, the 'phones charged, the fish tank at the right temperature, and have the coffee machine functional. To do it, I bought a camping battery. In my case, the 1.2kWh Ecoflow Delta, though there are a couple of other companies such as Jackery. It'll run the necessities of the house for most of the day. Plus, it's portable, so if I ever am out and about in the wild and need power, I'm sorted. I also need to go buy the panels for the thing, so that I can get a charge into it for possible multi-day cuts, not that they are common.

harderthanf · 04-10-2021 4:35pm

I grabbed two 100aHr (2.4 kwhr) lesiuire batteries (400 cycles AGM) for around 130euro each, a 1000W pure sine wave inverter, a mppt charge controller and 300W panel. This easily keeps the house going with broadband , access point, lights and tablets for longer than any outage we've had.

All this was around 550 euro and should do me for most of the rest of my life. 🤣

I've a fire man on my ground array and can't think of an easy way around it either!

VinLieger · 04-10-2021 5:06pm

Just stumbled across this thread as ive begun to look into solar and storage as im guessing have many with the potential blackouts we may have going forward during winters. But this sounds like it makes the whole thing a bit pointless if during a blackout your system also automatically stops even if you have power stored? What is the reason for this and is it likely to change?

bullit_dodger · 04-10-2021 6:27pm

The reason (briefly) is that the wiring is a two way circuit. When you house needs power you take it from the grid, when you have excess you can give it out.

Problem with a powercut/blackout, is that your inverter doesn't know if the grid is down for a deliberate outage, or the electricity cable down the road knocked down by a tree. So for the tree issue, ESB "power down" that area so the electricians can go work out and safely work on the fault. If in the meantime, you are quiet happily chucking 220v out into the wild, while ESB have turned off their side, your about to give some poor electrician a bad day.

So when inverters detect no grid voltage, for safety reasons they will go inoperative. Now in theory you could safely set one up that it can work in an outage, but it requires creating separate isolated circuits in your house. Most people, unless you have some skill in the area should avoid. I know enough, to know enough that it's not worth it for me.

Manic Moran · 04-10-2021 8:06pm

https://www.boards.ie/discussion/comment/117976001#Comment_117976001

In fairness, VinLieger's specifically asking about 'if he has power stored'.

I don't know if there's any specific regulation on the matter in Ireland, but around here, systems with storage systems will switch to drawing from the storage system during an outage, though systems without storage (mine included) will cease solar production for the exact reasons you give. I don't know if the panels will recharge the storage during an outage, however (i.e. if, for safety, they can draw from the battery, but not produce for anything).

"All this was around 550 euro and should do me for most of the rest of my life. 🤣"

How the hell did you find 4.8kWh of battery for EUR550?

harderthanf · 04-10-2021 10:23pm

https://www.boards.ie/discussion/comment/117976476#Comment_117976476

the two together are 2.4kWh, not 2.4 each!

sozbox · 04-10-2021 10:58pm

https://www.boards.ie/discussion/comment/117975008#Comment_117975008

Where did you buy yours if you don’t mind me asking?

Manic Moran · 05-10-2021 12:23am

https://www.boards.ie/discussion/comment/117977225#Comment_117977225

Still a good deal. Amazon's showing the Ecoflow at $1,100 right now, that's just 1.2.

Soz, at Amazon.

Capt'n Midnight · 05-10-2021 1:11am

Germany had a partial eclipse a few years ago where 15GW of solar dropped off the grid for a few minutes and it was managed.

Have a plan B. Grid outages aren't normally long and your phone has a light build in. Work out what else you need over short time scales. My parents got a bottled gas cooker as a backup for cooking, could have been used for boiling water if needed.

Longer time scales would require you to have more backup. Go read a book.

harderthanf · 05-10-2021 8:16am

https://www.boards.ie/discussion/comment/117977695#Comment_117977695

I am not familiar with the Ecoflow. I just took a look and the battery chemistry is different to that battery I have. As it's lithium if will have a better depth of discharge, closer to 0% (but I'm not getting into that argument !), where as most LA batteries shouldn't really drop below 50%. Also, the weight difference is huge. Still, for what I need the AGM's are perfect.

I see the Ecoflow is just 18650 cells. If you were anyway handy you could make a pack with new (or used) 18650's, a BMS, inverter and the sockets/ports for an awful lot less that what they're advertised as. The do look handy though!

harderthanf · 05-10-2021 2:00pm

Coincidently we just had an unscheduled power cut here from 10am until 14:00 - happy I had that battery and kit in place. Broadband, wireless, laptops all working. Hope this isn't the start of things to come this winter

Nutzfahrzeuge · 05-10-2021 4:18pm

Sorry for asking a dumb question - but how do you get an Ecoflow to power your house during a black out? Presume you cant just plug it into a socket and it works in "reverse" ?

harderthanf · 05-10-2021 5:25pm

https://www.boards.ie/discussion/comment/117980121#Comment_117980121

Technically that will work, but do not do it!

I have the battery pack as a stand-alone unit. When the power goes I roll in the pack and just unplug the devices I need (from the mains) and plug them into the inverter sockets on the pack. I have a few low power (~7W) lamps that I can plug in around the place too. So bare minimum I can light the house and keep the kids occupied with phone/Switch/YouTube etc. while herself can gander at Netflix etc on the tablet. It's not a full drop in replacement but it definitely helps

garo · 05-10-2021 9:10pm

https://www.aliexpress.com/item/4001083766967.html

LifePO4 is safer than 18650. Also cheaper. The set about was 1275 last week. 10.24kWh.

the_amazing_raisin · 05-10-2021 10:38pm

https://www.boards.ie/discussion/comment/117976001#Comment_117976001

It depends on the inverter, but some of them have a system called anti islanding built in. Or it can be installed separately

Basically if it detects any unusual behaviour from the grid, it'll isolate the house from the grid. So the solar and batteries (or generator) can continue operating

It's very similar in function to an automated transfer switch you'd have with a backup generator

Here's an example of one system

https://www.victronenergy.com/accessories/anti-islanding-box-63a

bullit_dodger · 06-10-2021 12:26am

Anyone got any recommendations for some UPS boxes? Thinking of maybe ~1.0 Kwhr or there abouts for the telly.

Thanks.

randombar · 06-10-2021 1:48pm

So I've a back up cable coming back into my main fuse board.

My understanding is that, that is essentially wired into the fuse board and I can switch over to that when the power goes, but I would have to disable a few CBs if I don't want that power going to every device / plug ?

Manic Moran · 06-10-2021 2:38pm

https://www.boards.ie/discussion/comment/117980394#Comment_117980394

This.

Part of the reason I picked the Ecoflow unit which I did is that it has a 'draw limit' sufficiently high that it will run some more power-hungry items at the same time. It's not just a matter of how many kWh the battery stores, but whether it can provide that power quickly enough to meet devices which use electricity more rapidly. You can imagine that charging your iPhone will take far less of a draw than running my American-sized fridge-freezer. Most camping batteries will have multiple power sockets, but are not expected to run major appliances, so if I want to run, say, my main fridge-freezer, the deep freezer, the fish tank and charge my 'phone all at once, with the high draw limit I can do it with the unit I have (Using 50' extension cables, granted), although, of course, for less time than running just the one item.

Plus, of course, I can use it for other things. It's in the garage right now, powering my tyre inflator.

tails_naf · 06-10-2021 7:28pm

https://www.boards.ie/discussion/comment/117983456#Comment_117983456

If you allow the backup to power your main fuse board, you have to cut off the supply to the grid, that's the crux. That'd why I'd like a single switch that connects in the backup supply while at the same time disconnecting the grid (and inverter primary output). This would allow the fuse board to supply the house but also make it safe to someone working on the grid. If there was a switch like a double pole double throw, capable of handling grid current it would be ideal.

MAULBROOK · 06-10-2021 7:42pm

If you have a Solis inverter their is a backup plug on it, so i just put a single socket on it and during a power failure I just run the extension lead out to it.

Now depending your battery output that is. I'm lucky our setup can output 3.5kw. no problem for coffee makers or a kettle. I could easily run the TV router and sat box for a number of hours, god forbid we have to acutely talk to other members of your family.

Knowing your setup is key to this, you need to understand what it can or cant do.

Many people with solar and a battery have this in place without knowing it. TBF you paid a lot of money for it, why would you not try and learn what it CAN do for you.

NOTE, not all setups are the same and some don't have this facility.

harderthanf · 08-10-2021 9:51am

https://www.boards.ie/discussion/comment/117983908#Comment_117983908

Yeah, that is a good point. That really comes down to the inverter though and for small (relative) current an SLA battery is comparable to any other chemistry regarding max C-rating and/or in rush amp limits.

The Ecoflow's are nice bits of kit but extremely overpriced for what you actually get. However, for most people, the price is easily offset against the hassle of building a pack yourself!

edit: just looking over the Ecoflow spec and although it doesn't say it, it must be using a pure sine wave inverter as it mentions be able to use devices with motors etc. This would bring a "self-build" pack price up a little bit.

randomname2005 · 08-10-2021 10:12am

https://www.boards.ie/discussion/comment/117975443#Comment_117975443

Any links/brand names and models for the components for us newbies to this game?

harderthanf · 08-10-2021 10:40am

https://www.boards.ie/discussion/comment/117991878#Comment_117991878

Well, there are loads out there - but a lot seem to be out of stock , especially the batteries. Here is a few items I've used over the years (for pack builds and/or shed/small office setups). They're on the cheaper side so add +- 50% if you want to increase capacity and/or brand name!

You will also need some sundries like MC4 connectors, 12v cable and fuses/busbar. All of the below comes in at around €460. Also, if you have large-ish car and can get to the wholesalers you can pick up a single 300W panel for around €100 +VAT - they tend not to deliver single panels (or at least charge for pallet size) as they're too big for the standard couriers.

B Class Lesiure Battery, walk in off the shelf

https://www.halfords.ie/camping-and-leisure/caravan-and-motorhomes/halfords-leisure-battery-hlb700-682063.html

MPPT Charge controller

https://www.amazon.co.uk/EPEVER-Controller-Automatically-Identifying-Voltage/dp/B0721QNDQD/ref=sr_1_5?crid=3PPDDZRE8MTVC&dchild=1&keywords=epever%2Bmppt%2Bcharge%2Bcontroller&qid=1633685337&sprefix=epever%2Caps%2C143&sr=8-5&th=1

1000W (2000W peak) Inverter

https://de.eco-worthy.com/collections/solar-wechselrichter/products/1000w-12v-solar-wechselrichter-dc-12v-ac-220v

Example of usb charge you can use from the battery

https://www.amazon.co.uk/Charge-Charger-Aluminum-Voltmeter-Motorcycle/dp/B07NV7579D/ref=sr_1_10?dchild=1&keywords=fast+charge+12v+usb&qid=1633685463&sr=8-10

100W Panel

https://de.eco-worthy.com/collections/solar-module/products/100w-12v-monokristallines-solarpanel

300W Panel

https://midsummer.ie/buy/Clearance/qcell-325w-mono

randomname2005 · 08-10-2021 11:44am

https://www.boards.ie/discussion/comment/117991997#Comment_117991997

You make it seem so easy! Many thanks for those links. When I searched leisure battery I was getting random things over €1000. Halfords makes more sense.

I am sure I will have a ton more questions, including how to get this past the other half, but very interesting.

Edit: First question! Somebody, possibly bullit_dodger in the solar pv quotes thread, suggested some ideas for garden mounting, and one option would be on a vertical wall. I know, not ideal from a capture stand point, but possibly the only place I could do it. Is there anything specific I would need or could I just grab the cheapest roof mounting rails and use those? Would be looking at mounting to concrete fence pillars.

harderthanf · 08-10-2021 12:16pm

I've mounted a good few panels over the years to vertical walls. Take a look at these images. It's crude but works very well. The panels are on hinges so I can change the elevation with the lower arm over the year.

panel1.jpg

panel2.jpg

Furze99 · 08-10-2021 12:27pm

Depends where you live I guess. In an urban area, unlikely to be lengthy power cuts as even in storms, faults in such areas get fixed first. Living rural you could be waiting days, standard generator is the way to go to get water into the house and charge devices. After that, rechargeable lanterns and solid fuel stove.

randomname2005 · 08-10-2021 12:59pm

https://www.boards.ie/discussion/comment/117992463#Comment_117992463

Nice, seems doable. Thanks again

https://www.boards.ie/discussion/comment/117992518#Comment_117992518

I live on the outskirts of a small town in Galway, defined as urban for electricity prices, but probably have more cows in a 100m radius around the house than people! In the event of a grid supply issue, being able to have a few things running for a few hours would be nice. Same in the event of a fault on the grid. If I do go down this line, part of this would be to satisfy the geek in me, part to have some power in the event of an electricity outage.

bullit_dodger · 08-10-2021 5:32pm

https://www.boards.ie/discussion/comment/117992677#Comment_117992677

Mentioned previously (sorry can't remember who to give credit), but most inverters or the batteries themselves have an 'emergency' outlet so if you have a battery in your solar installation a cheap-n-cheerful solution would be to run an 20m extension cable from that outlet to the living room and plug in the telly and or router (assuming your load network hub has power but that's another problem for another day)

Depends on how accessible your installation is of course. But might be a lot easier than building an off grid solution? (but it's a lot of more fun to come up with an off-grid solution to be fair)

randomname2005 · 08-10-2021 6:18pm

No battery, don't think my standard Solis inverter will have a plug. Looking at pics online it doesn't appear so.

graememk · 08-10-2021 6:50pm

https://www.boards.ie/discussion/comment/117994449#Comment_117994449

Only a hybrid inverter will have an eps output

randomname2005 · 08-10-2021 9:52pm

https://www.boards.ie/discussion/comment/117994586#Comment_117994586

Figured as much, but always nice to get it confirmed by more knowledgeable people.

randomname2005 · 08-10-2021 9:53pm

https://www.boards.ie/discussion/comment/117992463#Comment_117992463

What is the most per hungry thing you run?

harderthanf · 10-10-2021 1:14pm

https://www.boards.ie/discussion/comment/117995371#Comment_117995371

I've had a lot of setups over the years, so running alsorts really. Even now, and although I've just under 7kwh of an array feeding the house, my garage is on its own circuit. That has a fridge, lights, laptop and a couple of power tools - chop saw etc. All from battery and inverter

randomname2005 · 11-10-2021 9:32am

https://www.boards.ie/discussion/comment/118000578#Comment_118000578

7Kw is a nice size!

randomname2005 · 16-10-2021 7:14am

https://www.boards.ie/discussion/comment/118000578#Comment_118000578

Circling around this in my head still. How many panels do you have connected to your garage grid, and what size batteries to run that stuff in the garage?

prosaic · 16-09-2022 4:15pm

What if I make a pretend grid supply?

Turn of grid at meter box. Have a small battery plus inverter to generate 220V (or could it be lower like 210V) that you can switch into the primary output of the solar inverter. Turn off any heavy power using equipment. The solar inverter and fireman's switch would think that the grid is up and running so the solar would work away. What are the issues with this approach?

Does the solar inverter need to sense the flow on the CT clamp in order to work right?

tails_naf · 21-09-2022 11:57pm

Some inverters have a backup output. So I guess if you either connect critical loads to this, or else isolate the main output and connect the backup output via a two pole switch, in theory you can have this drive the house. You need to isolate any path out to the grid also though. Ideally wed have a smartet fireman switch setup, that allowed the house to run in the absence of the grid, but still be disabled by a switch in the meter box.

mswomex · 01-10-2022 11:43am

I have a Solis inverter (2.4Kwp) with a Pylontec battery installed a year ago. If I knew then what I know now and how the setup is configured to operate under various circumstances I would not have invested in a battery at all as I do not believe that they are a great bang for your buck. The Pylontec (2.4kwh) was €3k + vat. You would think that for that money you would be able to run your house for a decent amount of time. What I have found is that it will run the house from maybe 6pm onwards for the rest of the day on a full charge. However, turn on one of the big drainers ( oven, dishwasher, washing m/c etc.) and it wouldn't pull the socks off a deadman! So for me at the moment it feels like a bit of an expensive ornament 😁.

Which, leads me to the reason for my post. I have a long extension lead connected to the backup outlet of the inverter. Reading previous posts I see now that during a blackout I will not have supply from the panels available ( it's all in the small print isnt it 😕) and would be solely reliant on whatever SOC is available via battery. I have been trying to configure the solis not to discharge the battery so that at least I have maximum charge available for an outage ( at least configure it this way during winter period when conditions would not be generating really any excess charge to battery anyway). I have not had any success though. I have tried to configure the discharge time to a few mins a day but Solis seems to ignore that setting. If there is any charge there it will feed it to the load regardless. Can I just turn off the battery when fully charged and turn it on again when there is a blackout during winter? Or am I stuck with the expensive ornament!😁

jkforde · 02-10-2022 8:20am

how about go on a Day\Night tariff and fill it at night so you can minimise Day rate usage until some solar surplus starts to refill it (Nov, Dec, Jan notwithstanding). you can turn it off but then you really do have an expensive ornament for 99% of the time, I mean, how many power cuts do we get? maybe 2 a year, where we are anyhows

btw, let us know if you're thinking of selling the 2.4 Pylontech

mswomex · 02-10-2022 12:44pm

@jkforde It is already configured to charge off grid by installer (00:00-01:00) but come 8AM has drained to its discharge SOC. I'd still be at the mercy of good timing of a blackout and having sufficient charge built up.

There has to be a better solution.

jkforde · 02-10-2022 1:01pm

https://www.boards.ie/discussion/comment/119691811#Comment_119691811

so why not set to charge from grid at the end of the night rate window (0000 - 0900, 2300-0800)? so for example 0600-0800?

Jonathan · 02-10-2022 1:08pm

https://www.boards.ie/discussion/comment/119688381#Comment_119688381

You can set a battery reserve mode on the Solis. This means that during normal operation, the battery will not discharge down below a configured SOC, to keep a reserve for use with the backup socket.

Solar in a blackout

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