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 Post subject: Building a System, Cost Observations
PostPosted: Mon Mar 31, 2008 8:03 pm GMT EstGMT 
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Guppy
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Joined: Thu Dec 06, 2007 11:34 am GMT EthGMT
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Location: Maine
I just wanted to point out that it seems to me, if someone wanted, they could put together a decent grid tied system for alot less than what is advertised in packaged systems from most companies. I see that 3.0kw systems run around $22,000. I just ran some numbers, did a little research, and looked for deals. Even without the great deal I got on our solar panels, you could build a very nice system with high quality parts. For example, If you bought 16x190w "sun" panels from sunelec, the rebranded evergreen panels, a Xantrex GT 3.3, 2 6inch Schedule 40 pipes about 11' long, cement, 2 8 Panel Direct Power & Water Racks, enough conduit and 8ga copper wire to run 100ft, Grounding lugs, ground wire, ground rod Midnight Solar MNPV6 and 2 15A fuses, and a 20A 240v Circuit Breaker. You could do it all for $15,000 or less. Am I wrong? Let me just point out that this is the Same system I just built with the exception that I used Sunpower Panels that I got a good deal on and my inverter cost more because it was positive ground. The whole nine yards came in under $15,000 for us and we made some mistakes too. Thats a savings of $7,000 if my math serves me right, and they are on Racks too, not roof mounts which are stuck at 1 angle all year and 1 direction all day. Pole mounts give us the option change the angle easily and to manually track the sun if we are home by turning the array about every 1.5 hours, about 4 to 8 times a day depending on the time of year. If you live in a place with alot of open space, you may wanna reconsider those roof mounts.


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 Post subject:
PostPosted: Mon Mar 31, 2008 11:22 pm GMT EstGMT 
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Red Cobra Delta Guppy
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Joined: Sun Jun 02, 2002 1:01 am GMT EndGMT
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Location: Lakeland Florida
This isn't anything special about solar, just about every trade has the 50/50 rule, meaning supply costs are 50% of the retail price.

Very few people have the skills to tackle something like solar that requires cash, good shoping skills, understanding electrical and mechanical systems. You got off easy because you had no permits to deal with another thing most people have no clue how to handle

I have even less cash invested than you, I got panels at 1.5/2.5/2.90 watt over the last 4 years, my inverters were part of work with Xantrex and I did all the work myself. So sure, it can be done for ALLOT less

I'm looking at replacing the AC/Heat pump in my home, local contractors want 7-10K to put in a SEER15 system , I can buy the "parts" in tampa for 3200 ... Same thing. Maybe 1 days work, looks like brazing is the next trade to tackle!

By the way, my main motivation of the years to learn all these trades wasn't to save money, it was for me anyways, harder to find contractors than learn the trade. Its also good in slow times to be able to draw on more than one talent for income.


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 Post subject:
PostPosted: Tue Apr 01, 2008 8:51 am GMT EstGMT 
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Guppy
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Joined: Thu Dec 06, 2007 11:34 am GMT EthGMT
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Location: Maine
Good points SG. I was thinking about helping a friend of mine build his own system, he saw how well mine worked and told me if I could build him one for the same price he would go get a loan ASAP. It wouldn't really make sense to sell systems for profit around here though, $15,000 is starting to push the limits of affordability in Maine. There are plenty of installers around here but when you call and talk to them they all seem to now only as much as they need to in order to install 1 particular type of system. They either do grid tied, or battery backup, but never both. If you asked someone to design a system that does both they would say... Well Why on earth would you want to sell back to the grid? Or they would say, what do you need batteries for? Then if you start to get technical with them they try to tell you its so comlicated that someone at home really can't handle it themselves. I say they are all full of BS and are only in it for the money. If you want a system to pay you back in in as much time as it will take to pay the loan back, you better do it yourself. As far as installing goes, everyone that I talked to that were certified installers who would qualify the system to get the state rebate, said that installations START at $2000 for small systems that barely qualify for the state rebate. Basically in order to get the Maine State Rebate, you have to spend in excess of $4000 on the installation. Which means that even with the rebate included and tax credits, you would still save a minimum of $2000 or more by doing all the work yourself and ignoring the rebate all together. By the way SG, must have been nice getting panels $1.50 a watt!!! HOLY SHISTA! :shock:


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 Post subject: Re: Building a System, Cost Observations
PostPosted: Wed Oct 22, 2008 11:04 am GMT EndGMT 
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Minnow
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Joined: Fri Oct 17, 2008 8:07 am GMT EthGMT
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I replaced two A/C systems in my home 2 years ago this past July and never regretted it one bit. I had a 10 SEER 3.5ton unit downstairs and a 10 SEER 2 ton unit for the upstairs. I replaced the upper unit with a 14 SEER TRANE 2 ton with a variable speed air handler which, BTW, not considering the 5KW electric heat strip, only draws 800 mA running for cooling. I didn’t want the heat-strip even installed but my installer said it was needed for de-icing the compressor during reverse heat pumping in the colder months. He told me with the combination of the VS A/H and the 14 SEER compressor I would get the equivalent of a 15 SEER unit. The down stairs got a 15 SEER 3 ton TRANE with a variable sped A/H as well. I had to drop the breaker size on both units back, the 3 ton went from a 40A 2P to a 20A 2P which was a problem, I had to replace the wire as you can’t fit #6 AWG on a 20A 2P breaker. The 2 ton dropped back to 15A 2P. I have been very pleased with these units, they cut my electric bill by about 40% and the 2 ton unit runs great on my stacked SW5548 TRACE inverters. I have a friend in the A/C business do the install so the whole setup with all new copper lines completely installed was $8,000.

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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 10:13 am GMT EthGMT 
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Catfish
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WizBandit wrote:
I replaced two A/C systems in my home 2 years ago this past July and never regretted it one bit.

I didn’t want the heat-strip even installed but my installer said it was needed for de-icing the compressor during reverse heat pumping in the colder months.

I have been very pleased with these units, they cut my electric bill by about 40% and the 2 ton unit runs great on my stacked SW5548 TRACE inverters. I have a friend in the A/C business do the install so the whole setup with all new copper lines completely installed was $8,000.


I too have been wondering if I could eliminate the heat-strip on one of the two A/C systems for my home here in Central Florida. I have been wanting to set up the one on the XW6048 inverter, which would easily do it without the heat strip.

I'm just wondering if this is a good idea though, mostly because twenty years from now somebody buying the house would be upset if the heat strip wasn't connected. I guess it is a bit of a proceedure to disconnect and reconnect the heat strips on the units I have.


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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 11:07 am GMT EthGMT 
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Red Cobra Delta Guppy
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Joined: Sun Jun 02, 2002 1:01 am GMT EndGMT
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It takes 10 minutes to disconnect the heat strip in my air handler ( pull one wire ). If I ever sell, it would be another 10 minutes to reconnect

If your home has good insulation, here in central Florida, heat strips are not needed.


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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 1:31 pm GMT EthGMT 
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Minnow
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Now you have me in the "thought process" again darnit. I never gave it much because here in Tarpon Springs, FL we use the A/C for cooling way more than for HEAT. But, we do have some bone-chilling cold days here that require some form of Heat. We rarely use the A/C in HEAT mode as we do have a fireplace. BUT, I have the 2-ton on the Stacked SW5548 setup and I'm not sure if the inverters would support the heat strips in the 2-ton's airhandler. I think I will install a relay that is only on the main "grid" panel that stays on only while the grid is up. I can use this to wire the "heat" wire from the thermostat so heat will only work if the grid is on.

I read somewhere and was told by my A/C friend that it was not a good idea to disable the heat-strip in a heat-pump split system and here is why. In reverse heat pump mode the reversing valve located outside near the compressor "switches" the roles of the two coils. The coil in the airhandler now is used to blow heat, the coil in the compressor unit is blowing cold (simplified explaination). If the dew point and temperture outside are just right and the system has been running a while trying to get you some heat, the compressor coil will ice up, like a big block of solid ice and that is very bad. The system has sensors that can tell when this happens, I'm guessing using system pressure. It will stop the reverse action, turning the unit back to cold inside and heat outside, turn on the heat strip at the same time, which is why the heat strip is before the coil on heat pumps that need to do this. This action now sends heat into the coil, some heat out into the room and forces the unit outside to thaw the ice as it is pumping the heat basicly out of your warm room to do this. The heatstrip comes on for two reasons, to assist the thawing and to prevent snow from being dispensed from the grill over your head.

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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 1:59 pm GMT EthGMT 
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Red Cobra Delta Guppy
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That doesn't make any sense. The Heat Strip is in the air handler. In Heat pump systems, the heat strip is in addition too what ever the heat pump is supplying btu wise and only comes on when the temperature difference is more than 3-5 deg from the setting desired or with that famous "emergency heat" setting. It has no effect what so ever on the compressor and outside coils. If the outside is freezing up, the unit will simple reverse the flow, and self generate heat. It does that about every 30 minutes on my unit in very cold weather, its automatic.

My zero energy home built in 1999 ( sol in 2003 ) has gone thru much colder weather than any coastal location, without a heat strip now for 9 years. The key is a well insulated home , r40 ceiling and R11 walls.

The only use for heat strips with heat pump systems is for poorly insulated homes that a heat pump in sub 40 degree weather can't overcome the btu loss in the house, it serves no other purpose. Unfortunately here in Florida, that covers just about ever home built before 1995 or so. The very first thing people should do is make sure they have minimum R40 ( 14" of blown in fiber glass ) in our state, but few have ever heard this or understand why it makes such a large difference


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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 3:52 pm GMT EthGMT 
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Minnow
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If the outside is freezing up, the unit will simple reverse the flow, and self generate heat. It does that about every 30 minutes on my unit in very cold weather, its automatic.


A heatpump can not "self generate heat". Have you ever put your hand on an air grill in the house while this is happening? "usally" the air would be close to room temp because the heat strip is on (generating heat), if you think about it, you are in summer "cold" mode during this defrost and with the outside temp down around 40 degrees you should feel air coming out at about 38 degrees, cooling the room down fast, even if just for 60 seconds. If you have disconnected your heat strip, you should have VERY cold air during the defrost cycle. The system is a heat pump, it can't make heat, it just moves it from inside to outside, or outside to inside. The heatstrip makes heat during the defrost cycle to replace the heat being pumped out of the room defrost the outside coil, otherwise it would get start to cool down inside.

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 Post subject: Re: Building a System, Cost Observations
PostPosted: Fri Oct 24, 2008 6:31 pm GMT EthGMT 
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Red Cobra Delta Guppy
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Joined: Sun Jun 02, 2002 1:01 am GMT EndGMT
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Location: Lakeland Florida
When a heat pump is in defrost mode, its simply running in cooling again and yes it need btus to raise the coil tempatures to get ride of any frost. What is NOT required is a heat strip. The Air being taken from the living area is ideal as heat rises and most areas heat pumps are used the return is in the ceiling. There will be cooler air for the 5 minute defrost cycle, but regardless of a heat strip or btus stored in the ceiling air, energy will be used for the defrost.

The point is a heat pump doesn't require a heating strip and in our mild climate, it is not necessary for the 1-3 night a year we get below freezing. Without a heat strip, all the heating btus are being generated at a COP of 3-4 vs a COP of 1 with resistance heating.

I've done it, it works fine and I'm in an area that easily gets 10 degrees colder than Tarpon Springs


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