Inverter Temperature Derating

[moggy1968]

oh yes, to have a good quality system, you need a good quality system, not just decent panels. The components need to be properly matched.

You wouldn't put bicycle tyres on a ferrari!

 

[FB.]

I've had a max/min thermometer in the loft for the last few days, to see what the temperature variation has been.

Days have been sunny - sometimes a little haze or a thin cloud - with outdoor temperatures peaking around 26'C.
The loft has been peaking at 33'C; 7'C above ambient.

It should be borne in mind that about three-quarters of one roof aspect has now been covered by solar panels which will be blocking the sun's heat from that direction (but that would be the case with most solar arrays; it covers part of the roof and keeps the roof cooler).

If the roof hadn't been part-covered by panels then I suspect it would have added about 11'C to the loft temperature, taking it up to about 37'C in recent days (taking into account the additional unshaded roof and its likely ability to absorb the sun's heat).

I remember having to change the ball and float on the water tank in my old house on a hot sunny day about ten years ago and it was probably 40'C in the loft.

 

[babba]

I've had a max/min thermometer in the loft for the last few days, to see what the temperature variation has been.

Days have been sunny - sometimes a little haze or a thin cloud - with outdoor temperatures peaking around 26'C.
The loft has been peaking at 33'C; 7'C above ambient.

It should be borne in mind that about three-quarters of one roof aspect has now been covered by solar panels which will be blocking the sun's heat from that direction (but that would be the case with most solar arrays; it covers part of the roof and keeps the roof cooler).

If the roof hadn't been part-covered by panels then I suspect it would have added about 11'C to the loft temperature, taking it up to about 37'C in recent days (taking into account the additional unshaded roof and its likely ability to absorb the sun's heat).

I remember having to change the ball and float on the water tank in my old house on a hot sunny day about ten years ago and it was probably 40'C in the loft.

So you should not put inverters in lofts ?

 

[Earthstore]

So you should not put inverters in lofts ?

This has been covered before, but just a little refresher; Most installs differ, and it can be a case of saftey over performance, DC cables have no mechanical protection, no trips, nothing. So if you feel it is safe to route DC cables through a house with 600V+ maybe to gain a little performance on a hot day, then that is your decision, As FB stated the temperature in his loft was 33 degrees, so he was way below the 40 advised for the SMA, the biggest loses come from the panel temperature and not the inverter.

 

[FB.]

This has been covered before, but just a little refresher; Most installs differ, and it can be a case of saftey over performance, DC cables have no mechanical protection, no trips, nothing. So if you feel it is safe to route DC cables through a house with 600V+ maybe to gain a little performance on a hot day, then that is your decision, As FB stated the temperature in his loft was 33 degrees, so he was way below the 40 advised for the SMA, the biggest loses come from the panel temperature and not the inverter.

I agree. The panel output is about 20% lower in this weather, so the inverter won't be running as hot, so may cope with a slightly higher temperature than expected.

I have a P1 Aurora indoor model in a downstairs utility, which hasn't exceeded the outdoor 26' temperature in recent days, whereas it would have been 33'C in the loft (perhaps another degree or two warmer in the loft due to the inverter's own heat generation; the inverter adds a few degrees of heat to my cool downstairs utility room), but even if it was in the loft, it should still be within its 40'C de-rating.
Mine runs two strings, running down the outside of the house in a conduit on the wall between mine and the neighbours house, so out of view. Cables come back into the house next to the inverter, into two DC isolators. The DC voltages are about the same as mains voltages (200-300V DC, 7-8A current at full power).

I find the inverter's location convenient for taking a look at what it's doing without needing a desktop monitoring device (costing £100+ and which may only last a few years like most electronics) - the screen on the indoor model is more useful than certain other inverters - pic below:

 

[babba]

DC cable can be protected, I think the inverter will be working its socks of in tempetures stated by FB and is sure to shorten its life

 

[moggy1968]

DC cable can be protected, I think the inverter will be working its socks of in tempetures stated by FB and is sure to shorten its life

All things being equal we will mount the inverter somewhere other than the loft, but sometimes it's inevitable. SMA HF and TL inverters are rated to 60C so typical loft temperatures are well within it's operating range.