Solar Panels <> Resilience

[Graham.]

I admire your altruism in choosing a system that benefits the rest of us, but if you wanted solar energy you could directly use yourself, maybe it was mid-sold? (!)

[AnthonyL]

[Andy Burns]

How well do you think two houses with solar panels would get on trying to supply the whole street's cookers/showers/electric cars? Of course the real reason the inverter shuts itself down is to avoid zapping the chaps fixing your supply ...

[dennis]

They could have but they need some extra kit.

One thing they must not do is power the network if its dead, doing so could get a worker trying to fix it killed.

It wouldn't be difficult to have an inverter and some batteries connected so the panels would still operate without the mains but you would also require some sort of switch to ensure you didn't power the network.

In most cases it isn't worth the cost.

[Theo]

They can, if they have batteries and appropriate controls. If they don't have batteries, they're at risk of a brownout or cut if the sun happens to go behind a cloud at the wrong moment. That could be unfortunate for equipment that isn't expecting intermittent power - and isn't uncommon in our weather.

You can get controls that switch over the house to solar power, while preventing making the inlet live and frying any technicians working on it, but presumably your neighbours didn't invest in such things.

Theo

[T i m]

Talking to the owner of a mostly electric narrow boat the other day, he ditched his solar panels completely (as they failed) as they were not really able to contribute much to the solution, even on a 'good' day.

They may have their place, but not even as a UPS on a sunny day apparently? ;-(

Cheers, T i m

[Theo]

Narrow boats are, well, narrow, and moorings are often shaded by trees. That wouldn't be my first site for a solar installation. Better to have the panels on land and feed in the power to the boat via a wire with a mains plug on the end.

THeo

[T i m]

Yeah, but they are about as wide as a reasonable Solar Panel and often

60-70' long. ;-)

That is true.

No, but many do have quite a few panels so I'm guessing they mush have some use, if only / mostly in the summer and for recovering *some* charge in the Aux / Main batteries?

Again, you are right of course [1] but that sorta defeats the whole 'mobile / off grid home' thing. ;-)

In this case the boat is equipped with a 600cc twin cylinder diesel engine that is run high up in it's efficiency curve when needed to (only) charge the batteries.

As a spinoff of that the engine also provides underfloor heating via it's cooling circuits.

The interesting bit is that he was saying that the LA batteries really needed regular (fortnightly) 'balancing' and if running off grid, that mean running the engine / generator at less than a full load for several (~5-6) hours. If a mains power socket was available that is much more efficient of course.

As an alternative to using the generator for the balancing / equalisation / de-stratification stage, he was considering using some form of Lithium battery or even SuperCapacitor, as they could use the spare power after the end of the main battery bulk charge phase and neither would need much balancing?

I've not read / absorbed all the tech details on his handout yet but he was also saying the boat was too heavy and he will have to remove some ballast. I was surprised to learn that the batteries weren't part of that ballast (in the bilges etc) but were in the main accommodation area as such?

So his was a 'diesel electric' (with batteries) in a similar way a diesel electric train or ship might be, whereas some other hybrid boats could drive the prop with electric motors or the IC engine directly. Apparently that causes a big compromise because of the revs / torque available and he the size of prop required (bigger for electric). But why couldn't they drive the big electric prop from the IC engine via a reduction gearbox of some sort? Reduced efficient (losses in the gearbox) possibly?

Cheers, T i m

[1] Someone was asking me about the idea of a solar powered, battery stored, portable waterpump for allotment use. The water is delivered to IBC tanks via some plumbing (and water butts from the rain etc) but needs to be delivered to the plants manually. I suggested that maybe a leisure battery and suitable low power pump (possibly submersible) could do the job but like you, suggested the panels might be on top of a 'docking shed' or some such?

[spuorgelgoog]

Bilges tend to be wet and mucky places, not the ideal location for batteries.

Owain

[Andy Burns]

The ambulance chasing lawyers do need a new target after next Thursday's PPI deadline ...

[Jethro_uk]

Well it *used* to be such systems were inherently battery powered, and could survive a loss of mains power.

Of course in these days of spivs and spin, it would not surprise me to know where any cost savings in such a system came from.

Even in the days when I had more confidence in the mains supply than I do now, I would have insisted that anything so critical had a backup for power cuts.

Going back 20 years ago, we had some electric window openers fitted (SWMBO couldn't reach the windows) and they were battery powered via the mains. As was her lifting chair.

[harry]

Grid linked solar panels are designed to be "anti islanding". It's a safety thing and it would be impossible for them to meet the load alone.

You can get a "stand alone" system for more money which has batteries included.

[Martin Brown]

They have to drop out or be isolated completely from the mains grid and then be provided a reference 50Hz pilot. It is possible but not common as it is more expense and complexity for a rare situation.

Someone in that position should have an automatic fallback so that when external mains fails the system can be switched to internal power and a generator set starts up (with manual intervention or more expensively automatically start up after mains power fail). The guy who lived opposite had such a system to support his 95 year old father in law.

[Jethro_uk]

I think batteries are an easier option ? You only really need a little bit of power to operate the equipment for a short outage.

Obviously if you are experiencing regular, prolonged outages, a different approach may be needed.

Generators aren't a magic bullet. They need maintenance and testing.

[Andrew]

No standard PV insulation has off-grid enabled. They need to rely on power from the network to generate the correct waveform for starters (didn't we have this discussion with the recent failures at a wind farm?), and also there is the safety aspect so you don't electrocute someone working on the line.

This also begs the question, if the frequency dropped below

48.whatever, shouldn't thousands of domestic PV systems say, ooops, don't like this, and shut down too?.

[Andrew]

I'm waiting for all those 'aggrieved' state pensioners who were contracted out for much or even part of their lives, to demand COMPO for their 'loss' of the full 'new' state pension.

How about car owners who have never made a claim ?. They'll be wanting their premiums back.

[Andrew]

Friends up the road have these. There are two big rotary switches (those things sitting in a wall box, and are about 4 inches across).

One (I think) cuts off the DC power to the panel, the other isolates the output from the inverter from the mains.

[The Natural Philosopher]

They did. 1/2GW dropped off the grid.

[Bill Wright]

NHS outreach beds don't have a battery. All stairlifts do have a battery.

Bill

[Andrew]

The Himolla Zero Stress reclining chairs either run off a big brick transformer or a battery pack, so its not difficult to do.