Sunny Boy 5000-TL fan?

[captaindomon]

I'm having a Sunny Boy 5000-TL installed. I notice there is an optional fan kit that is installed by default on the 6000 and 7000 watt models. So my question is, should I install one in my 5000? My garage where the inverter is installed is inside in the shade, but hits 100 degrees during the summer. It will be connected to 5175 nameplate watts of SunPower modules with no shading, facing due south at about 35 degrees, so I expect production to be within limits for the inverter but at almost full capacity. The fan kits look like they are about $100.

[J.P.M.]

I'm having a Sunny Boy 5000-TL installed. I notice there is an optional fan kit that is installed by default on the 6000 and 7000 watt models. So my question is, should I install one in my 5000? My garage where the inverter is installed is inside in the shade, but hits 100 degrees during the summer. It will be connected to 5175 nameplate watts of SunPower modules with no shading, facing due south at about 35 degrees, so I expect production to be within limits for the inverter but at almost full capacity. The fan kits look like they are about $100.

My garage temps. [~ outside ambient + 5-10 deg. F, depending, and array size (5.232 kW) with a 5 kW inverter ( rebadged PowerOne)] are somewhat similar to what you report. Before I got a fan, I'd check to see what type of flow the fan is supposed to provide through the unit (not free flow - but actual flow rate after installed. Some bolt on units are more for making the user feel good than effective.

FWIW: My high tech window fan under the inverter blowing upward seems to lower the heat sink temp ~~ 18-20 deg. F. when the inverter output is ~ 4,000 - 4500 Watts.

A pretty typical example: Today, data at 1230 PDT, garage temp. 85 F, heat sink temp. 133 F. with the fan off. The fan was turned on @ ~ 1235 PDT. Data @ 1250 hrs.: garage temp.~ 87 F, the heat sink had dropped to 111 F., air outlet from inverter ~98.1 F., inverter output 3.96 kW, and pretty steady (3.93 - 3.96 kW) from ~ 1215 to 1310 PDT or so. If the inverter is something like, say, 97% eff., that means something like 400 or so BTU /hr. gets generated as waste heat.

If (133 -111)/(133-85) =.46 of that is taken off by the fan, --->>> ~185 BTU/hr. is taken away by the mechanical ventilation. If so, a few boring calcs. cranks out an air vol. flow rate of something like 15 or so CFM through the unit's heat sink fin assembly.

I'd suggest that the above is back of envelope stuff, but does seem to point to about a 20 deg. F. drop with some mechanical ventilation is possible and measureable. Those values seem pretty typical of what I measure, with about a 45 -50 deg. F. diff. between the heat sink temp. and the garage air temp. when the inverter is close to full rated output, and ~ 25 - 30 deg. F diff. and the inverter under close to full rated output with the fan operating. What I have is NOT efficient, but it is simple and seems fit for purpose. BTW, The fan draws about 73 Watts ~ = 249 BTU/hr.

Off the subject: Some other #'s for those interested: At 1250 hrs., the irradiance input to the array was ~22,888 W, based on measured horizontal irradiance of 702 W/m^2 and calc'd P.O.A irradiance of ~ 877 W/m^2. That calc's to a net system instantaneous efficiency of 3,960/22,888 ~ = 17.3% or so. the array average cell temp. at that time was ~ 54.8 deg., and the roof ambient air temp. was 30.9 deg. C. The current fouling rate is thus ~ 2.2%, but that's probably no better than +/- 0.75% if I'm lucky.

[solar pete]

Wow, hows that for an explanation nice

[J.P.M.]

Wow, hows that for an explanation nice

As usual, take what you want, scrap the rest. If you like our service, tell your friends.

[captaindomon]

That's awesome, thanks for the detailed info!

[solarix]

I would say trust the SMA engineers to not need the fan on a 5kW. All the TL inverters use the exact same housing so the larger kW sizes need the fan to get enough cooling from the same heat sink. Of course, heat is the enemy of electronics and while there are many that think installing microinverters on roofs is OK, adding a fan to a TL might be good insurance - hard to say if worth $100 though.

[PVAndy]

I would say trust the SMA engineers to not need the fan on a 5kW. All the TL inverters use the exact same housing so the larger kW sizes need the fan to get enough cooling from the same heat sink. Of course, heat is the enemy of electronics and while there are many that think installing microinverters on roofs is OK, adding a fan to a TL might be good insurance - hard to say if worth $100 though.

I wouldn't add the fan on a 5K -22. We've installed several hundred of them and they run pretty cool as long as you have good air space above and below. My personal system uses 2 6K -22's with fan, I run 7.5 kW DC into each and rarely ever does the fan come on.

Andy

[J.P.M.]

That's awesome, thanks for the detailed info!

You're welcome. Meant only as a serving suggestion and info only. The fan was about $12 @ big box.

[J.P.M.]

I wouldn't add the fan on a 5K -22. We've installed several hundred of them and they run pretty cool as long as you have good air space above and below. My personal system uses 2 6K -22's with fan, I run 7.5 kW DC into each and rarely ever does the fan come on.

Andy

If I was running an inverter co., I might think about not putting a fan in a design in a borderline case if it meant an increased probability of extending the design's fleet statistical life span much beyond the warranty period.

However, a hundred bucks and some fan noise but not much circulation can help people believe they have a cooler running and thus longer lasting unit. Happy cust., increased profit. What's not to like.

[sensij]

I haven't attempted to replicate it, but there is some evidence that a cooler inverter will work more efficiently, shown in this thread. I doubt the fan would be enough cooling to recover the power required to operate it, but if you are thinking it is insurance that might prolong the life of the inverter, the cost to run it might be less than it appears on the surface.

[J.P.M.]

I haven't attempted to replicate it, but there is some evidence that a cooler inverter will work more efficiently, shown in this thread. I doubt the fan would be enough cooling to recover the power required to operate it, but if you are thinking it is insurance that might prolong the life of the inverter, the cost to run it might be less than it appears on the surface.

FWIW, I haven't been able to document an increase in eff. using methods I've described here. Out/In on the inverter seems to run pretty steady @ ~~ .969 - .971 regardless of fan running or not. I'd need to get beyond 97 % or so. I don't think that's in the cards for a reasonably efficient inverter. As in: 5,000 Watts going up 1% in eff. , 97 to 98 %. Possible ? maybe. Likely ? I'm skeptical. Increased life from lower temps ? Maybe to probably. Quantifiable ? Probably not. A good idea ? Probably but hard to quantify from a cost standpoint. If I could squeeze 50 more Watts out of a 5KW inverter for less than 50 Watts of fan power, it might be worth it. But, as it is now, 73 watts of fan power doesn't produce increased eff. that I can see from the inv. screen for increased air flow. Maybe others have diff. #'s. I'm sure I'm not the only game in town.

[captaindomon]

Thank you everyone for your advice! With the 50 watt increase in efficiency at 70+ watts fan usage example, combined with a great installer that doesn't think I need one and a good SMA warranty, I think I'm going to pass on the fan for now, and then monitor temps carefully next summer when things heat up. I can always install the fan at that time if it starts having issues.

[bcroe]

I'm having a Sunny Boy 5000-TL installed. I notice there is an optional fan kit that is installed by default on the 6000 and 7000 watt models. So my question is, should I install one in my 5000? My garage where the inverter is installed is inside in the shade, but hits 100 degrees during the summer. It will be connected to 5175 nameplate watts of SunPower modules with no shading, facing due south at about 35 degrees, so I expect production to be within limits for the inverter but at almost full capacity. The fan kits look like they are about $100.

Some in the electronics industry think the primary reason to add a fan, is to increase reliability or extend
life. This won't happen if the fan rarely runs (controlled). Your results may vary. Bruce Roe

[Willaby]

Some in the electronics industry think the primary reason to add a fan, is to increase reliability or extend
life. This won't happen if the fan rarely runs (controlled). Your results may vary. Bruce Roe

My fan cooling solution for my SE5000 (when I get around to it), will be to mount a small ~10 watt panel to the roof eve, wired down to a computer fan. More sun = more fan speed and no timer. I've had a solar attic fan running for a couple years now. I can't say it helps keep the house noticeably cooler, but the attic is. which reduces the load on the AC system.