|
Post by StepfordRenegade on Jul 17, 2014 8:08:21 GMT 10
Solar questions for any electrically minded folks...
We have solar power but no battery bank. What happens to the power generated by our panels when the grid goes down (e.g black out). I was under the impression that the power from the panels flows through the house wiring first, and any excess goes back into the grid. Does this mean in a blackout that our appliances (thinking fridge mainly) will be getting some power while the sun is shining?
I have heard that the electrical company can automatically shut off your solar so power doesn't flow into the grid while they work on downed power lines. Can you turn it back on in a SHTF situation?
Battery banks can be ridiculously expensive. Does anyone know of an economical set up, big enough to run a fridge, that we could hook up to our existing panels?
Thanks in advance for your time!
|
|
|
Post by graynomad on Jul 17, 2014 9:33:49 GMT 10
I'm not very familiar with grid-connected systems, there may be some clever circuitry inside the inverter that isolates it from the mains wiring when there is no external power, it would be possible to do but I don't know if they implement that. I would think that you would have to install a manual changover switch.
If you add a switch then you may be able to run autonomously, but then again if the inverter is smart enough to detect the mains power it may still shut down. In the absence if a real expert here you may have to ask the installer or inverter supplier.
I don't know if the electrical supplier can switch off your inverter, it makes sense for the reasons you state, but for the same reason you would not be allowed/able to switch it back on or you would fry the workers. Once again a changeover switch would be the answer as long as the inverter will run with no external power.
As for the batteries, the size of the bank required depends on how long you expect to be without sun, to get you through the night I would think 2 batteries would suffice, certainly I've lived off two batteries for months running two fridges, but they where small DC models. This requires a charging source every day though so if the sun don't shine you'll need a generator.
Now all that said I'm pretty sure you can't add batteries to your grid-connected inverter because it's not designed to be a charger as well, but that doesn't really matter because you can use a separate charger, if this is a backup system only then a cheap trickle/maintenance charger is all you need unless you plan to also charge from a gennie, then a good three-stage charger would be better.
|
|
|
Post by pheniox17 on Jul 17, 2014 11:24:38 GMT 10
I'm going to try and keep the theory as simple as possible for you your solar system goes through a inverter... electricity is lazy, it will power your house before leaking into the grid but because the inverter is tied into the grid there is risk of "islanding" what that is, (a example) a power line has been knocked out causing a localized blackout, energex shuts power to that line to repair it... but how do you shut off that 240vac back to grid power?? that line becomes live, and a danger because of islanding inverters have a blackout "off" switch, so when there is a blackout there will be no power from your inverter to your home... there will still be power from your solar panels... but the inverter been switched off means no power for your home... so to sum it up 1. grid goes down 2. your in the dark
|
|
sentinel
Senior Member
Posts: 463
Likes: 253
|
Post by sentinel on Jul 17, 2014 11:36:40 GMT 10
I'm going to try and keep the theory as simple as possible for you so to sum it up 1. grid goes down 2. your in the dark I loike simple!!
I loike summing it up versions!!!
So - to do it right you'd need a axillary battery pack back-up to cover yourself.
Did I get that right???
|
|
|
Post by StepfordRenegade on Jul 17, 2014 11:45:48 GMT 10
1. grid goes down 2. your in the dark Bummer, that's what I thought. Any ideas on how to make it so this isn't the case, without forking out for a full off grid set up?
|
|
|
Post by graynomad on Jul 17, 2014 12:39:39 GMT 10
There's no technical reason an inverter can't do all you want (after all mine would do if it was grid connected), but given that it was installed as part of a grid-connected system I'd say there's no way it can because it wasn't designed to do so. If the brief is "keep a fridge and maybe a few other small things running on solar during a blackout" one way (and the simplest I can think of right now) is as follows Get - 1 or 2 batteries
- solar regulator
- small true sine wave inverter
- A generator and charger if you think you will have long periods with no sun.
Wire them up permanently to the panels (in parallel with the existing inverter), then when the power goes out unplug the fridge and whatever else you need to keep running and plug them into the new inverter. When the power is on the solar will lose a little current to keep the batteries charged, but not much. That's the cheapest way I can think of (except just using a generator, in which case that's all you need) and it doesn't require any mains wiring so you can do it yourself.
|
|
|
Post by pheniox17 on Jul 17, 2014 12:56:26 GMT 10
there is a way to bypass the power off safety, but that will take a lot of research you will need a electrical diagram of the inverter, then locate and bypass the safety switch, I would only consider doing this if its a shtf american blackout type of event you need there to be no rule of law, as unless you install a switch to/or remove main grid connection you risk a lot of law suits... just as a start but for here and now, look up the info, work out how to disconnect the house, and just roll with the punches having the ability to store unused power for night time is a good idea
|
|
|
Post by pheniox17 on Jul 17, 2014 18:31:38 GMT 10
had a bit more of a think on this
what would I do if I had a tied in inverter with solar (on the house)
I would first locate and look at how to bypass the safety switch... and how to remove mains power from the house (remember the grid is down)
look at what I plan on providing power for at night
I won't have my lights on at night anyway...
maybe some power tools, torches, radio...
as I don't want the world to see me as having power, so I would invest in battery chargers and rechargeable batteries for the technology I will use, and leave it there (this is very inefficient way to charge batteries) so wouldn't recommend for off the grid set ups but for Joe blow with a existing back to grid set up this will work nicely...
a 3kw system will provide plenty of power to use, just make sure you use your freezer to help with cold storage (ice placed in fridge over night) and you still try and maintain opsec... (air con, lights, loud music/TV/DVDs)
I would also have electrical tape on hand for making the disconnection of main power safe (grid comes back on will = death)
the biggest plus is fire risk, you reduce it .. once the grid is off, solar still generates power = risk, when power comes back on there will be a massive spike in electrical caused fires (the surge will cause damage)
|
|
|
Post by StepfordRenegade on Jul 17, 2014 20:30:21 GMT 10
Cool, thanks heaps pheniox17 . I'll have a look online and maybe print out some diagrams, instructions etc. for how to bypass the safety switch and disconnect the mains. Obviously would only do this in a WROL situation, proper TEOTWAWKI situation. I wouldn't want to run anything obvious at night, just keep the fridge cold. I would also have electrical tape on hand for making the disconnection of main power safe (grid comes back on will = death) I don't understand this comment about the electrical tape though, can you please put it in have-no-idea-about-wiring terms?
|
|
|
Post by pheniox17 on Jul 17, 2014 21:28:25 GMT 10
I would remove the actual mains wires into the house, that's very easy when there is no power... but you will end with 2 exposed large gauge wires, covering the wire with electrical tape will make it safer if power comes back on
small scale, speaker wires, there is normally a exposed silver or copper wire at both ends, the rest is covered in "plastic"
now imagine (yes hard) that lethal amounts of power is going into the wire
its completely safe to pick up
but if you touch the ends, you will have a very bad experience
what you are using the electrical tape for is to cover one end of the wire (cover both wires separate) and don't be afraid to use a lot of tape.
now back to the large scale, (it is illegal to do this so teotwawko only) your doing exactly the same, except the wires you're covering are as thick as one of your fingers...
this makes what you have just completed (removing your house from the grid) safe,
if power comes back on you need to call out a election to re connect you to the grid... but you also remove islanding effects from the solar setup... this steep has to be done before adding any bypass, its 3 parts safety 1 part opsec...
think of it as a important steep, get off the grid before stuffing around with the inverter...
there are more safety guidelines, but think on the lines if its plugged in its dangerous, so unplug it before working on it..
|
|
|
Post by You Must Enter A Name on Jul 23, 2014 19:19:04 GMT 10
Good info on safety, as it is often overlooked. You a sparky?
|
|
|
Post by pheniox17 on Jul 23, 2014 19:59:32 GMT 10
No license,
|
|
Paco
New member
Posts: 5
Likes: 4
|
Post by Paco on Aug 9, 2014 0:09:17 GMT 10
If you disconnect the main line into your house, whether live or not, will cause the inverter to think the grid is down and go into standby mode?
I know my inverter is designed to stop all power to house and importing to grid when is senses no AC current from the mains, which is to protect Mr Energex as he tries to fix the lines. Not sure how big a battery system needs to be but maybe a small one could work that would supply a day or two of basic appliances.
When all else fails, wait until night time and put an axe through the cables from the panels and then attach them to a car battery or deep cycle
|
|
|
Post by pheniox17 on Aug 9, 2014 0:16:05 GMT 10
All it is (in the inverter) a internal switch, and that's the definition of islanding The theory here is a long term grid down (American blackout) scenario... So even in your case, find the bypass, disconnect from the mains (properly) and then bypass the switch, and you have a small supply of power, but this also gets into a lot of legal issues and only to be attempted as a "long term grid down" emergency
|
|
|
Post by dellarius on Aug 10, 2014 15:33:47 GMT 10
Hello all, first post.
So your inverter does switch off when the grid go's off, this stops EMF from entering the power grid to allow linesmen fix the overhead lines. With this said when a linesman is working on your power line they will earth both sides so if someone does have a rouge solar inverter they'll be "safe"
Only in an emergency situation touch your wires, dangerous stuff. An alternative to taping up electrical wires is using something call Single or Double Screw Connectors, we call them BPs in Queensland. Having these in your tool kit would be handy if you're a prepper so you can wire up 12, 24 or 240 power systems so they are safe and manageable. If SHTF you'll be able to securely wire two or more electrical connections together.
My general advice is learn a little about electrical safety and even how to wire ELV systems (12,24 VDC or 32 VAC).
|
|
|
Post by You Must Enter A Name on Aug 10, 2014 15:49:11 GMT 10
Hello all, first post. So your inverter does switch off when the grid go's off, this stops EMF from entering the power grid to allow linesmen fix the overhead lines. With this said when a linesman is working on your power line they will earth both sides so if someone does have a rouge solar inverter they'll be "safe" Only in an emergency situation touch your wires, dangerous stuff. An alternative to taping up electrical wires is using something call Single or Double Screw Connectors, we call them BPs in Queensland. Having these in your tool kit would be handy if you're a prepper so you can wire up 12, 24 or 240 power systems so they are safe and manageable. If SHTF you'll be able to securely wire two or more electrical connections together. My general advice is learn a little about electrical safety and even how to wire ELV systems (12,24 VDC or 32 VAC). Great first post mate,I appreciate the information. You should stop by the introduction section and let everyone know you are here. It sounds like you have some good information to share.
|
|
|
Post by thereth on Aug 11, 2014 3:07:54 GMT 10
if your not to 'switched on' with electrical wiring, a good option would be to go for your Restricted Electrical Licence, the course is done at night in some states and it goes a long way to teaching you the basics.... and as a bonus you get a D class licence as well!
|
|
|
Post by StepfordRenegade on Aug 11, 2014 7:41:55 GMT 10
if your not to 'switched on' with electrical wiring, a good option would be to go for your Restricted Electrical Licence, the course is done at night in some states and it goes a long way to teaching you the basics.... and as a bonus you get a D class licence as well! IN QLD a restricted electrical licence is only for people who have a legitimate need for it, e.g. a plumber who has to disconnect/reconnect an electric hot water system etc. in the normal course of their work. ... but I totally appreciate the pun
|
|
krull68
VIP Member
Posts: 535
Likes: 875
|
Post by krull68 on Sept 17, 2014 21:26:58 GMT 10
Some updates for everyone.
My friends have a solar instillation company where I live, and new tech is coming on the market. you can get a battery system that is hooked up to the mains. If a blackout happens, apparently it switches to internal only, then when the power comes back on, it reconnects to the grid.
This type of system has only been available for a few weeks, so time will tell if it is any good or work needs to be done to iron out the kinks.
If it does what it says, it should be absolutely fantastic, store your own power for night time use and still make some money off the power companies.
|
|
antiag21
Full Member
Posts: 58
Likes: 65
Location: Perth WA
|
Post by antiag21 on Sept 20, 2014 3:20:34 GMT 10
^^^^ this would be awesome.
|
|