25 kW Solar power project in Iowa.
- Thread starter Redneck in training
- Start date
OP
Redneck in training
Elite Member
I purposelly put the cost "as built" there so whomever is interested can do the math.
Qapla
Veteran Member
Since some if you guys seem to be well versed in Solar ... any idea if and how and how much it would cost do put in Solar to power my 5 ton A/C-heat pump package unit?
OP
Redneck in training
Elite Member
Since you live in FL your unit does primarily AC I am guessing. If I am not mistaken 5 ton=17.6 kW. Heat pumps have about 400% efficiency therefore the unit has about 4.5kW compressor. Actually better approach is to figure how much space you have available in example on the south facing roof. Based on the size of the HP unit (I am guessing) you burn about 23000 kWh/year. PV system producing 23000 kWh/year would have to be about 15.5 kW. The actual cost would then depend on DIY or turn key and location. Roof being the cheapest. I got quote for turn key $3.90/W in Iowa before tax rebate. We built our ground standing system DIY for $2.26 before tax rebate. Gainesville has solar coefficient 5.17 in other words 1 kW of installed PV power would produce (in average) 5.17 kWh/day.
If you would do it DIY I would recommend microinverters. It will increase the cost by about 7% but you will not burn anything or kill yourself. It is much easier to deal with single panel producing 30V/9A then a string of panels producing 600V/10-15A.
Just remember though about those micro-inverters is that the heat in the Fla Sun from May-Sept. will have them in the 110-120*F range or higher up on the roof under the solar panels. They have not been on the market long enough to make a judgement about how they hold up.
That would be my biggest concern.
That would be my biggest concern.
OP
Redneck in training
Elite Member
You have to use longer standoffs for better cooling.
schmism
Super Member
can you talk about the micro inverters?
I get that they generally have proprietary cabling and connections to the panels, but how does the AC side work. Do you simply use a junction box and wire nut 3/4/5 (whatever) AC leads together to join that many micro controllers all putting out 2 amps into a single 6/8/10 (whatever) amp AC lead? I assume they phase correct on there own somehow with electronics?
do you just run those AC legs back to a receptical/service panel to connect to the house/barn/shop?
is it possible to pull direct DC off the microinverters for battery charging or DC lighting? can you use a backup battery bank and microinveters together?
I get that they generally have proprietary cabling and connections to the panels, but how does the AC side work. Do you simply use a junction box and wire nut 3/4/5 (whatever) AC leads together to join that many micro controllers all putting out 2 amps into a single 6/8/10 (whatever) amp AC lead? I assume they phase correct on there own somehow with electronics?
do you just run those AC legs back to a receptical/service panel to connect to the house/barn/shop?
is it possible to pull direct DC off the microinverters for battery charging or DC lighting? can you use a backup battery bank and microinveters together?
OP
Redneck in training
Elite Member
Yes. Microinverters have special cabling with connectors spaced either portrait or landscape. It makes all connection quick and easy. You can chain up to 17 inverters/branch. Each branch has to have its own 20A breaker. They are grid comutated and produce "pure" sine wave. If the grid voltage drops below 210V or increases over 260V they disconnect from the grid. There is a possibility to use them also off grid. The battery feeds a "master" inverter that makes the microinverters think that the grid is up and running.
We have 96 inverters in 9 branches. Each branch is center connected directly to a breaker and via breaker box to the main cable and grid.
Qapla
Veteran Member
According to the data with the A/C unit it has a "total unit amps" of 30.7 and it is single phase 220-240v
At 240 volts that would be 7369 watts needed to operate the unit.
I would assume that would be for A/C-Heat Pump operation since it takes an additional breaker to run the heat strips. The heat strips are actually optional and the unit can run without them. In fact, the heat strips could be connected to the grid while the A/C-Heat Pump is run from the Solar Power.
As far as roof area, I have an East/West roof - no South facing roof. However, I have 30 acres so finding a place to put a free standing array would not be a problem. I am also capable of DIY.
With this information is it possible to give a more bottom-line type figure for the panels and inverters needed. As far as a frame, I am sure I could build something if need be.
At 240 volts that would be 7369 watts needed to operate the unit.
I would assume that would be for A/C-Heat Pump operation since it takes an additional breaker to run the heat strips. The heat strips are actually optional and the unit can run without them. In fact, the heat strips could be connected to the grid while the A/C-Heat Pump is run from the Solar Power.
As far as roof area, I have an East/West roof - no South facing roof. However, I have 30 acres so finding a place to put a free standing array would not be a problem. I am also capable of DIY.
With this information is it possible to give a more bottom-line type figure for the panels and inverters needed. As far as a frame, I am sure I could build something if need be.