Anyone have experience with these "solar assisted" air conditioner/mini split?

[neweclipse]

No doubt there is an exception somewhere. COP of course IS NOT on the label, but can
often be found with a little research. I would not risk buying some energy inefficient unit,
that refused to admit (because they are so bad) what the performance numbers were.

Just maybe, you could figure them out for yourself by comparing power input and BTU out.
1 KWH = 3412.142 BTU Bruce Roe

Let's pretend this is a consumers conversation and leave out the upper level engineering facts.

Low SEER=Bad...High SEER=Good... ...runs there about 13 up to 37 currently...COP does pretty much the same too as for Low to High, from 1 going up never surpassing 3 maybe???

(S)EER will get a consumer were he needs to be...anybody so inclined can have at it, and go nuts with their math and text books.

[neweclipse]

If one wants to hit the real high COP like say 6 plus, then look at solar assisted ground source heat pumps another form of geothermal.(SGSHP)
But I'm afraid that will bring out the math and text books...

[bcroe]

Ha I remember my 1972 AC was 8 SEER, last I heard still in service on a very light load. Geo thermal
was the obvious electric winner way back. Fine for a clean sheet brand new build. I looked at it a lot
in 2014, but it would be difficult to fit into this hilly homestead. The the cost was large, there was no
opportunity for DIY style savings, and it would take the rest of my life working to get the lawn repaired
back to the way it was. There is an additional problem, the thermal sink is limited, and it can freeze up
and quit on a long, cold winter. Then you are back to resistance heating, your SEER in the dumpster.
A sink big enough to entirely avoid this doubles the cost again. And there is the plumbing issue of
fluids and maintaining all those pipes, which will not last a lifetime.

When the current mini splits came out, they offered solutions to a whole list of my problems. They could
compete directly with geo thermal efficiency, and with my DIY input were far cheaper, could be tested
and then increased in total capacity, in installments. They will never freeze the ground solid, and my
latest claims heat to - 25F outside. I really liked decentralizing HVAC, so a single failure (like my blower
motor I replaced this month) cannot leave me in desperate straits. There are more advantages, also
some minor negatives will be described another time.

I noted some dual powered units listed a COP well above the 4 I look for. This I see as a rating
standardization problem. They are not using an amazing compressor to get a COP of 6, they are
comparing BTU out to line power in and ignoring the panel power input. Not a fair rating. Bruce Roe

FurnBlower.JPG

[J.P.M.]

This thread title is air conditioning and mini-splits...all mini-splits are NOT heat pumps either.

No consumer Label for an air conditioner or A/C only mini-split will revel a listed C.O.P., but engineers sure would get a chub if the label did.

That about sums that up...

Of course a consumer label won't show a C.O.P. - it's not required by law, so they don't bother. But C.O.P. was around a longtime before all the dumbed down EER came on the scene and was quite adequate until people got stupid. You want reality in comparing efficiency of HVAC equipment use C.O.P. , multiply by 3.412 for EER if it makes you feel better and don't waste time with SEER which is simply no more than smoke & mirrors.

[neweclipse]

Ha I remember my 1972 AC was 8 SEER, last I heard still in service on a very light load. Geo thermal
was the obvious electric winner way back. Fine for a clean sheet brand new build. I looked at it a lot
in 2014, but it would be difficult to fit into this hilly homestead. The the cost was large, there was no
opportunity for DIY style savings, and it would take the rest of my life working to get the lawn repaired
back to the way it was. There is an additional problem, the thermal sink is limited, and it can freeze up
and quit on a long, cold winter. Then you are back to resistance heating, your SEER in the dumpster.
A sink big enough to entirely avoid this doubles the cost again. And there is the plumbing issue of
fluids and maintaining all those pipes, which will not last a lifetime.

When the current mini splits came out, they offered solutions to a whole list of my problems. They could
compete directly with geo thermal efficiency, and with my DIY input were far cheaper, could be tested
and then increased in total capacity, in installments. They will never freeze the ground solid, and my
latest claims heat to - 25F outside. I really liked decentralizing HVAC, so a single failure (like my blower
motor I replaced this month) cannot leave me in desperate straits. There are more advantages, also
some minor negatives will be described another time.

I noted some dual powered units listed a COP well above the 4 I look for. This I see as a rating
standardization problem. They are not using an amazing compressor to get a COP of 6, they are
comparing BTU out to line power in and ignoring the panel power input. Not a fair rating. Bruce Roe

Your application is admirable, but your horror stories are just that...horror stories. There are many geo system out there working flawlessly but then nobody "Chirps" about any of that...
Been a DIY GSHP guy for 25 years. It's pretty simple with a drilled water well and a drain field for discharge. Ground water has none of your negative talking points. It's referred to as a "Pump and Dump" system and the pipes are never an issue. Ground water with it's constant temperature will beat any outdoor air temperature for COP...cannot pump heat that is NOT there...

[NochiLife]

I noted some dual powered units listed a COP well above the 4 I look for. This I see as a rating
standardization problem. They are not using an amazing compressor to get a COP of 6, they are
comparing BTU out to line power in and ignoring the panel power input. Not a fair rating. Bruce Roe

Could you please clarify the difference between "line power in" and "panel power input"?
I understand that "SEER" ratings are rather baseless, as "seasons" change based on where you're located. Conversely, an EER is based on "power used" vs "work done" (then there's the fun of BTU/W EER ratings vs. W/W EER ratings, with vastly different numbers). I am aware that the power usage at the rated output is generally less than the MAXIMUM possible power usage (is that what you mean by "panel power input"?), but most mini-split units can also produce more than their rated BTU/hr (at a significant loss of efficiency).

[bcroe]

Your application is admirable, but your horror stories are just that...horror stories. There are many geo system out there working flawlessly but then nobody "Chirps" about any of that...
Been a DIY GSHP guy for 25 years. It's pretty simple with a drilled water well and a drain field for discharge. Ground water has none of your negative talking points. It's referred to as a "Pump and Dump" system and the pipes are never an issue. Ground water with it's constant temperature will beat any outdoor air temperature for COP...cannot pump heat that is NOT there...

I had no intention of discussing a pump and dump system. I have little knowledge of
them, do not approve of the idea, it was NOT offered to me in 2014 for my own well and
septic, not sure it is even legal here, but saw one a few miles from here. My comments
are on closed loop fluid systems only. And what COP have you seen over 25 years?

Heat is everywhere there is matter. Bruce Roe

[bcroe]

Could you please clarify the difference between "line power in" and "panel power input"?
I understand that "SEER" ratings are rather baseless, as "seasons" change based on where you're located. Conversely, an EER is based on "power used" vs "work done" (then there's the fun of BTU/W EER ratings vs. W/W EER ratings, with vastly different numbers). I am aware that the power usage at the rated output is generally less than the MAXIMUM possible power usage (is that what you mean by "panel power input"?), but most mini-split units can also produce more than their rated BTU/hr (at a significant loss of efficiency).

By dual powered Mini Splits, I was referring to those with some combination of
solar panel power input, AC line input, and battery such as 48V input.

I expect the equipment to deliver the efficiency rating at maximum power, and
somewhere approaching the rating at lessor output. I do NOT expect more BTU
delivery than the output rating, keep in mind more BTUs are moved at the load
in heat mode than in cooling mode. Bruce Roe

[NochiLife]

bcroe Thanks for the clarification; I fully understand now. Using solar power does not magically increase the efficiency of the unit.

[Gilligan]

bcroe Thanks for the clarification; I fully understand now. Using solar power does not magically increase the efficiency of the unit.

I'm not doubting what you are saying but YMGI says something else. I honestly don't know anything about any of this so I'm not saying anything one way or another, just presenting what I'm reading.

[bcroe]

I'm not doubting what you are saying but YMGI says something else. I honestly don't know anything about
any of this so I'm not saying anything one way or another, just presenting what I'm reading.

That is just another example of what I said before. Look at all SEER with no panels, they are fixed
numbers. But the last one is all over a range, because the panel power they are NOT COUNTING
can vary so much. Then look above at EER, there is no line for panels, because the COP really
does not care where the energy comes from.

Not a true picture, better standard methods needed. Bruce Roe

[NochiLife]

That little set of details proves the point by bcroe. Notice that they do NOT give you an EER for "with solar panels." SEER ratings are completely subjective, so what's a smidge of fudging the numbers?

Basically, SEER/EER is calculated by measuring the AC power draw vs BTU out. The problem is, they are NOT factoring in the power generated by the solar panels, and thusly, it appears like the air conditioner can be very efficient.
BUT...if you are paying for electric, and want to reduce your electric bill by using a "solar assisted" air conditioner, this is exactly what you want to get, and it will give you the equivalent of up to 40 SEER. If you do not have any solar at the moment, this might be a great way to "wet your feet" and whet your appetite for more solar, as you literally only need the air conditioner, and a couple of (properly rated) solar panels. (Note, however, that it will not function without AC power, even in full sun. Much like most grid-tie systems.)

To be technical, the air conditioner is not actually achieving 40 SEER...but if we ignore the power generated by the solar panels (leaving it out of the calculation), it can under full sun appear to be a 40 SEER unit. Interpretation of statistics is pretty much everything; if the solar power was factored into the equation, the SEER would not have such an extreme range (SEER 20 without, and up to SEER 40 with).

[Gilligan]

So do you guys think it makes sense to get one of these systems and dedicate some panels to it.

VS.

Get a grid tie inverter and feed the system (even without net metering, as my system wouldn't be big enough to roll anything back yet) and get regular mini-splits with inverters?

I feel like the cost savings in the these (not needing an inverter) is attractive.

But then there is the waste of energy from the PV panels if I oversize it like I would probably do, so that even on cloudy days most of the energy is coming from the PV panels.

[bcroe]

So do you guys think it makes sense to get one of these systems and dedicate some panels to it.

VS.

Get a grid tie inverter and feed the system (even without net metering, as my system wouldn't be big enough to roll anything back yet) and get regular mini-splits with inverters?

I feel like the cost savings in the these (not needing an inverter) is attractive.

But then there is the waste of energy from the PV panels if I oversize it like I would probably
do, so that even on cloudy days most of the energy is coming from the PV panels.

My feeling is net metering is the best deal, no power wasted, and night backup. But
if you cannot arrange net metering, this will allow some savings, or take a lot of strain
off batteries. Bruce Roe

[Gilligan]

I won't have batteries.

These units use mains as their backup/night draw.