Renewables: "talking 'bout my generation"

EricMears

It's quite interesting to view GW as a 'religion'

You need to have faith that it's happening.

The details are far too complex for ordinary folk to understand so a group of self-appointed experts have to interpret it for us.

Any deviations from forecasts are given a plausible (or not ?) explanation by these experts.

To become one of the experts you have to believe in the subject.

Any investigation into the subject has to start from the premise that it's really happening and just concentrate on to what degree it is happening.

Larger and larger sums are demanded from the faithful to stop it getting worse - without any real explanation of how that money will actually help.

[Deleted User]

20kWh yesterday @ 84% target.

Would have hoped for more but the heat in the loft where the inverter lives is just nuts this month...

Still it's going to be a good month

KevinG

jeepjunkie wrote: »

Would have hoped for more but the heat in the loft where the inverter lives is just nuts this month...

I know that heat on the panels reduces their output but are you suggesting that the inverter temperature affects generation? I hadn't heard that one before, only suggestions that it may reduce its life.

Martyn1981

EricMears wrote: »

It's quite interesting to view GW as a 'religion'

You need to have faith that it's happening.

Hiya Eric, can I just say, whilst I appreciate that many people are still unconvinced that humans are causing global warming - AGW (man-made or anthropogenic global warming).

As far as I'm aware there is absolutely no argument that the planet has warmed up more (at a faster rate) in the last century than would appear to have happened in the past.

So AGW may be disputed by around 3% of climate experts [edit - may be 3% of climate science papers], but GW is simply a measure of average temps, and that is undisputed. With the bulk of warming being in the Arctic and absorbed by the oceans.

Also, climate change is often used as a debated point, but this is simply the effect(s) that global warming or global cooling has.

Sorry to be pedantic, but GW is a fact, and climate change is a result. The arguments are really about whether man has caused/influenced this current warming and the subsequent climate change effects. So it's AGW, not GW that is disputed.

Mart.

Martyn1981

KevinG wrote: »

I know that heat on the panels reduces their output but are you suggesting that the inverter temperature affects generation? I hadn't heard that one before, only suggestions that it may reduce its life.

Hiya Kevin. When an inverter gets really hot, it should start to throttle itself back, as less work, means less heat. If too hot it may shut-down completely until the temp goes back down. This will help lengthen, or should that be reduce shortening of life expectancy.

You'll need to go online and look up the specs/data sheet for your inverter to find specific info. As a rough guess, probably temps above 40C(?) will/might start to have an effect.

Mart.

KevinG

Martyn1981 wrote: »

You'll need to go online and look up the specs/data sheet for your inverter to find specific info. As a rough guess, probably temps above 40C(?) will/might start to have an effect.

Hi Mart, just checked and mine gives an operating temperature of -20 to +60 C (fully protected against over temperature). I've just stuck a thermometer up there to see what it's really like. I've noticed output has dropped slightly in the really hot weather, but it doesn't seem to be due to the inverter.

zeupater

KevinG wrote: »

Hi Mart, just checked and mine gives an operating temperature of -20 to +60 C (fully protected against over temperature). I've just stuck a thermometer up there to see what it's really like. I've noticed output has dropped slightly in the really hot weather, but it doesn't seem to be due to the inverter.

Hi Kevin

The inverter may have an operating temperature range as above, but that would likely exclude high temperature de-rating. For SMA inverters, at around 40C the maximum output is limited by software and as the temperature rises the limit decreases to an extent where at 60C the output is limited to ~60% of nominal ... above 60C the inverter will shut down.

( http://files.sma.de/dl/7418/TempDerating-UEN103910.pdf )

The reasoning behind temperature de-rating is that in theory, for every 10C increase in operating temperature you half the expected lifespan of an electronic system ....

HTH
Z

[Deleted User]

jeepjunkie wrote: »

20kWh yesterday @ 84% target.

Would have hoped for more but the heat in the loft where the inverter lives is just nuts this month...

Still it's going to be a good month

Just to follow on one day this week it only generated 15kWh when I would have expected ~25kWh

According to one of the UPS units the temp was 41c. Not sure of the accuracy but certainly the sweat was running off my nose when I popped up to loft to switch off the mac mini & ext drive as they were very hot to the touch and not behaving properly.

Oh well at least the inverter has a 20 year warranty...

KevinG

zeupater wrote: »

For SMA inverters, at around 40C the maximum output is limited by software and as the temperature rises the limit decreases to an extent where at 60C the output is limited to ~60% of nominal ... above 60C the inverter will shut down.

Thanks, I just checked the temperature up there and it's 32 C so I'm not too stressed about it. I'm sure it has been hotter but I'd be surprised if it got over 40.

Kernel_Sanders

Martyn1981 wrote: »

When an inverter gets really hot, it should start to throttle itself back, as less work, means less heat.

The first thing an SMA does is to switch on its internal fan. This happens in the mid 20s, so last month was the first time I had noticed it this year. I had mine fitted in a bedroom, partly because my dark grey concrete tiles used to send the mercury in the loft into the 40s. The panels have had a dramatic effect on those extremes though, even in late afternoon when the Sun's as much on my south slope. I've also had a desk fan trained on it to give it some extra cooling, but this doesn't seem to delay the internal fan, so I don't know if there is any point; but the leccy's free, so why not!