Pv solar install the inverter in loft or garage

Martyn1981

OK, firstly, I got lost about 4 pages back, so be patient with me, whilst I attempt to sum up.

Originally thought that the assumption was that a 20C difference between locations could / should give a 4 fold increase / decrease in life expectancy.

Eg if a loft 40C, and a garage 20C, then inverter life expectancies could be 3yrs and 12yrs respectively, or 12yrs and 48yrs, or maybe a bit of both, 6yrs and 24yrs.

However, now understand that life expectancy relates to component temps, not ambient (ok so far?). So we need to see how bad the difference is.

Is the garage an integral, double skinned, north facing garage, or an attached south facing, single skinned, with solar gain.

Similarly, is the loft, vented, insulated (against the slates / tiles), has thermal cladding (PV) on a large percentage (mine about 90%).

Assuming the worst, and stable 20C garage and 20-40-20C loft, am I right in thinking that the big question here is - how much effect does the ambient temp have on the component temps when working hard?

I believe that SMA inverters can actually have an 'exhaust' pipe to funnel the vented air directly out of a roof vent?

This is raising lots of questions with me (nosey wise, as my inverters are in coolish downstairs toilet) particularly the mention of a cupboard, earlier on. How big is the cupboard, how full is it, and does it have venting, if not, could an inverter heat up the volume, sufficiently to negate any benefits? After all a loft does have a huge volume of air to start with.

Don's in a slightly different position to me, as I understand it, as he's posted pics of his system nearly peaking in Jan / Feb when loft cold.

So many points, sorry for all the questions. Repeat the main one.

Anyone know how much effect a large but hot (40C is that possible) loft ambient would have on the component temp, and therefore life expectancy?

Mart.

grahamc2003

My sonnyboy is now sitting in my hallway (plans were to have it in the loft). Advantages are

- (much) lower maximum temps, so zero chance it derating due to ambient temps of >40C
- longer life due to less extremes of temperature
- the approx 10% inefficiency of conversion of dc to ac is recovered almost all the time as useful heat (that's what the big heat sinks on top are for). On the hottest summer days, that heat will be superflous, but all the rest of the time (330 days?), that heat will be a useful addition to the house heat.
- I can tap the display and read it any time I want (190W atm, how crap is that - mind you, I've used 100% of what I've generated so far), without spending £200 on a bluetooth module. (I have the eon monitor, which gives plenty of (buggy) displays at a much greater accuarcy than the owl).

Disadvantage (to some)

- it's easily visible (till I get it boxed in).

zeupater

Martyn1981 wrote: »

OK, firstly, I got lost about 4 pages back, so be patient with me, whilst I attempt to sum up.

Originally thought that the assumption was that a 20C difference between locations could / should give a 4 fold increase / decrease in life expectancy.

Eg if a loft 40C, and a garage 20C, then inverter life expectancies could be 3yrs and 12yrs respectively, or 12yrs and 48yrs, or maybe a bit of both, 6yrs and 24yrs.

However, now understand that life expectancy relates to component temps, not ambient (ok so far?). So we need to see how bad the difference is.

Is the garage an integral, double skinned, north facing garage, or an attached south facing, single skinned, with solar gain.

Similarly, is the loft, vented, insulated (against the slates / tiles), has thermal cladding (PV) on a large percentage (mine about 90%).

Assuming the worst, and stable 20C garage and 20-40-20C loft, am I right in thinking that the big question here is - how much effect does the ambient temp have on the component temps when working hard?

I believe that SMA inverters can actually have an 'exhaust' pipe to funnel the vented air directly out of a roof vent?

This is raising lots of questions with me (nosey wise, as my inverters are in coolish downstairs toilet) particularly the mention of a cupboard, earlier on. How big is the cupboard, how full is it, and does it have venting, if not, could an inverter heat up the volume, sufficiently to negate any benefits? After all a loft does have a huge volume of air to start with.

Don's in a slightly different position to me, as I understand it, as he's posted pics of his system nearly peaking in Jan / Feb when loft cold.

So many points, sorry for all the questions. Repeat the main one.

Anyone know how much effect a large but hot (40C is that possible) loft ambient would have on the component temp, and therefore life expectancy?

Mart.

Hi M

Decent summary ..... so to address the above we need to consider cooling mechanism employed in the inverter .....

To open the discussion let's look at the inverter design and say that a typical inverter from any decent manufacturer would be IP54 & IP65 rated for component protection, therefore the majority of radiated heat contained within the protected shell would be absorbed, leaving convection, or forced convection, across a heatsink surface as being the main cooling mechanism.

What does this mean ? - well effectively we have a source generating heat, a temperature differential between the heated mass and the ambient temperature of the surrounding air. Heat dissipation results from a convective current forming which moves a mass of air past the mass of the heatsource, the mass of the airflow (mostly velocity dependent) being related to the temperature differential between intake and exhaust and the cooling capacity of the airmass being related to the temperature differential between the intake air and the mass being cooled .....

What needs to be considered is that in a dry system there is no evaporative cooling effect from the movement of airmass past the surface to be cooled, therefore the surface will not cool if the air is at the same temperature as the mass to be cooled no matter what mass of air comes into contact with it, therefore the mass will continue to heat until a temperature differential allows cooling to happen.

Taking the above into consideration we see that the capacity for convection to remove heat depends on a temperature differential and the ability for the differential to drive a convective current, this capacity is effectively the same at a differential of 25C vs 75C as it is at 35C vs 85C, as is the case in a convective central heating environment, therefore raising the ambient of the air still means that the same amount of energy needs to be dissipated, therefore the components run proportionally hotter.

The only mechanisms which can be applied to assist cooling are to either increase the surface area to be cooled (which would likely increase the physical size of the inverter), or increase the mass of the air passing over the surface to be cooled by employing forced convection, which some, but not all, inverters do through switching fans on when a temperature threshold is reached in order to delay the requirement for temperature derating.

HTH
Z

zeupater

grahamc2003 wrote: »

My sonnyboy is now sitting in my hallway (plans were to have it in the loft). Advantages are

- (much) lower maximum temps, so zero chance it derating due to ambient temps of >40C
- longer life due to less extremes of temperature
- the approx 10% inefficiency of conversion of dc to ac is recovered almost all the time as useful heat (that's what the big heat sinks on top are for). On the hottest summer days, that heat will be superflous, but all the rest of the time (330 days?), that heat will be a useful addition to the house heat.
- I can tap the display and read it any time I want (190W atm, how crap is that - mind you, I've used 100% of what I've generated so far), without spending £200 on a bluetooth module. (I have the eon monitor, which gives plenty of (buggy) displays at a much greater accuarcy than the owl).

Disadvantage (to some)

- it's easily visible (till I get it boxed in).

Hi G

What model SMA inverter ? - some have bluetooth as standard - If yours does you could connect from a PC using a bluetooth dongle for <£10 ... it's useful if you want to access generation history etc.

HTH
Z

hp4020

My neighbour and I had identical systems installed last October, same panels, same inverter, identical roof pitch, identical orientations SSW.My Inverter was placed in Garage, as I had doubts about loft temp.Neighbours inverter was placed in loft as he was unable to site in garage.So far panels / inverter are producing identical results +/- 2kw per quarter.Will update as we head towards a glorious summer !!

don0301

grahamc2003 wrote: »

My sonnyboy is now sitting in my hallway (plans were to have it in the loft). Advantages are

- (much) lower maximum temps, so zero chance it derating due to ambient temps of >40C
- longer life due to less extremes of temperature
- the approx 10% inefficiency of conversion of dc to ac is recovered almost all the time as useful heat (that's what the big heat sinks on top are for). On the hottest summer days, that heat will be superflous, but all the rest of the time (330 days?), that heat will be a useful addition to the house heat.
- I can tap the display and read it any time I want (190W atm, how crap is that - mind you, I've used 100% of what I've generated so far), without spending £200 on a bluetooth module. (I have the eon monitor, which gives plenty of (buggy) displays at a much greater accuarcy than the owl).

Disadvantage (to some)

- it's easily visible (till I get it boxed in).

Fronius say, for my range of inverters anyway, you shouldnt install in an occupied living area

they also say if you box it in, you should apply a forced ventilation system. so thatll be more noise and cost to do it properly

larkim

Fronius (IG30 manual) say "During certain operation phases the FRONIUS IG unit may develop a slight noise level, for this reason it should not be installed in the immediate vicinity of living areas", so I suppose a hallway would be OK as you wouldn't mind a small amount of noise there. It also says don't install where ambient temps are > 50degC, so the 40degC being talked about before seems a little low!

Matt

Dave_Fowler

larkim wrote: »

Fronius (IG30 manual) say "During certain operation phases the FRONIUS IG unit may develop a slight noise level, for this reason it should not be installed in the immediate vicinity of living areas", so I suppose a hallway would be OK as you wouldn't mind a small amount of noise there. It also says don't install where ambient temps are > 50degC, so the 40degC being talked about before seems a little low!

Matt

The copy of the manual I was reading said maximum 50C too, but also said derated reduced output above 40C (or was it 42C? - can't remember)

Dave F

Martyn1981

grahamc2003 wrote: »

My sonnyboy is now sitting in my hallway (plans were to have it in the loft). Advantages are

Disadvantage (to some)

- it's easily visible (till I get it boxed in).

G. Doubt you'll value my opinion, but my two sunnyboys do buzz, not too much, can't hear them in kitchen through wall to downstairs toilet, but fair buzz when peaking. Not sure if there is an associated vibration.

Really unsure about boxing in, regardless of views on ambient temp, I'm sure the sheer volume of available air is extremely important when these are running pretty damned hot. Hence my earlier concerns about fitting in a cupboard. You'll also need, at the very minimum, to leave a substantial amount of space on all 5 (free) sides when boxing in. Would suggest large vents and 'exhaust' pipe (appropriate SMA model) to remove forced air.

Maybe think twice and see how you get on for now.

Mart.

The_Green_Hornet

The instruction manual for my particular model of Sunny Boy includes the following information:

• The ambient temperature should be below 40 °C to ensure optimal operation.
• The Sunny Boy must be easy to remove from the mounting location at any time.
• Do not expose the Sunny Boy to direct sunlight, so as to avoid power reduction due to excessive heating.
• In a living area, do not mount the unit on plasterboard walls (or similar) in order to avoid audible vibrations.
  The Sunny Boy can make noises when in use which can be regarded as a nuisance when installed in a living area.
• Observe the minimum clearances to walls, other inverters or objects as shown in the diagram in order to guarantee sufficient heat dissipation and to have enough space for removing the Electronic Solar Switch. The minimum clearance in the diagram being 20 cm from top and sides, 50 cm from the bottom and 5 cm from the front.

If you check the manual for your own particular model then you shouldn't go far wrong.