Opinion on Solar PV System for my house

[Vic99]

I'd be grateful if you could help me. I posted this on a solar website as well. I know a few of you run solar here or follow it a lot.

I think I am ready to pull the trigger on a system in Massachusetts. I did a lot of research, but will be spending a lot of money and I'd like your opinion as to if this seems a solid system and if the price is in the ball park. I got two local companies evaluate my site. we worked through a system to meet 95% of my needs and both companies priced it with similarly within a few hundred bucks. I wanted to go with a bigger system, however.

Goal: Grid-tied, roof mounted solar PV to meet the majority/all of my electricity needs now and have room for the addition of an electric car in 4-5 years.

My site is south facing, most of the roof where the panels would fit would be at 28 degrees, four panels would be at 55 degrees. They calculated I'll get about 82% sun year round, this is after I had a tree taken down and a few branches trimmed. I'm told the Tigo maximizers will not only help with efficiency, but also prevent shade on one panel from killing the rest of the panels production. I was told that microinverters are not suitable for the 327 Watt panels. I talked to one guy who had a set up like this for a year and he was happy with it.

After several questions and a few revisions below is what seems to be the best. I haggled with this company after the initial proposal and got them to knock 1,000 bucks off. Below is the final price.

"5.56kW Photovoltaic system:
17 SunPower 327 watt High Efficiency photovoltaic modules, 1 SunPower inverter, 17 Tigo Power Maximizers, and all necessary balance of system materials (racking, wiring, disconnects, etc.). This price for complete, turnkey installation including all permits and rebate paperwork.


Gross Price $37,895
Less Commonwealth Solar II base rebate* - $2,000
Less CSII Moderate Home Value Adder rebate* - $2,000
Less anticipated 30% federal tax credit* - $10,169
Less anticipated 15% state tax credit* - $1,000
Total anticipated cost after rebates and tax incentives: $22,726


The above system would produce approximately 5,600kWh/year, which is an estimated 128% of your current electricity consumption. The anticipated payback period is 6-9 years and this includes the electrical upgrade to 200A service."

The last 2 years I've consumed between 4.25 and 4.5 MW annually.

Massachusetts allows solar home owners to sell SRECs. This year they are going for about $500/MW. The ceiling for the program is $540 /MW this year and next. The price will go down over time, but the floor is something like $170/MW and I'd be in for 10 years.

The company also told me to figure that I'd spend some cash to replace the inverter in ~15 years.

Thanks.

 

[peakbagger]

The price is high per watt but the power maximizers are probably adding a lot of dollars. There are one or two inverters with dual MPPT inputs so you can optimize two sets of panels. The odds are your 28 degree panels will be useless in snow conditons unless you can rake them which would be a good case for at least two MPPT controllers one for the 28 degree set and one for the steep set.

If you have multiple persistent shadows then string inverters are the perferable approach. I dont see power maximizers around for long and they are a lot of extra expense. I would stick with smaller panels that will work with microinverters. Many inverters have 10 year warantees. At the end of ten years I would be surprised at how much the technology has changed, if you can buy a replacement it will look a lot different.

In general there is a going to be run on solar in Mass as thestate have painted itself in a corner on rewewable now that they have cut off biomass power plants. Their only currently choice is Wind or Solar. Given the high cost of both and cheap natural gas power, the ratepayers are going to start to get grumpy when the utilities start increasing the rates substantially to cover the extra cost. Hydro Quebec is lurking in the background and if Mass changes the rules to buy Hydro Quebec power as renewable than dont be surprised if any incentives go away rapidly.

You may want to talk to Revision Energy as a third bidder, they are NH and Me based but may over the state line, they do a lot of volume.

 

[Vic99]

I have heard more than once that maximizers seem to be on the way out. A microinverter that handles panels larger than 250W must be in the works. I did talk to a guy that uses Tigo power maximizers and he says that work great. I'm hoping to talk to another in the near future.

I called Revision and set up an appointment. They talked about an AC panel that therefore does not require an inverter. Know anything about this?

Peak, did you have a thread on your set up? What do you think is a fair price? I already haggled and they knocked $1,000.

 

[StihlHead]

I would go with a system like Solar City has, and just pay the lower utility bills to them. That way to do not have to pay for anything and get savings from day one. You also do not have to do very much and they pay for the upkeep over time. 22 grand is a large output for solar that far north and 10 years is a long time to recover your costs. Another issue besides inverters failing is that the panels start to decline in output from day one. Over time they produce less and less energy. Many times these systems are obsolete by the time they are paid for.

And no, I do not work for Solar City, or any utility company (I am an electrical engineer though). I am just referencing Solar City as an example of a typical solar lease system that is common here in the PNW.

 

[peakbagger]

I dont have a thread set up but I am also on the solar forum you posted.

The cost of equipment is pretty easy to figure out, the market is so competitive that no one company gets a great discount, although I dont have a good source for the price for racking. From there its the how much profit they want to make and their cost of labor. I would make sure that they are doing all the work and that they dont sub contract it. Many firms make their profit up front and then get low ball bids from electricians to do the actual wiring. I dont do installations (except my own as I dont have a license), I just read a lot of posts on what others are reporting plus there are various solar industry sources that report out on occasion. What they cant factor in is ease of installation. Of course Lowell Mass is high labor cost so that probably drives up the labor portion

"AC panels" are DC panels with microinverters attached to them. Good odds they are standard panels with Enphase microinverters. There is no central inverter, each microinverter feeds into a specialized AC line that eventually terminates in your subpanel. A nice thing with microinverters is that they can be monitored remotely on the web, I dont think power maximizers can but not really familiar with them in detail. I have heard that the installed cost for a microinverter based system is just about equal to a inverter based system as the labor to install is less with microinverters.

Be aware that a contractor is not going to be able to guarantee "close out" or liquidation panels. I bought a set of Evergreen panels through a bankrupcy sale for 93 cents a watt delivered, but I am taking the risk if they fail ( I have a spare that will be shared with another system). A legit firm will go with a panel supplier that is in business and can honor a warantee although these days, no one knows what companies will be left after the shakeout. Most panels if they fail will fail quickly so you have a good chance of a warantee for a few years. If you have one damaged 8 years out good luck. Plan on $2 per watt for a panel more if you go with microinverters (remember you dont need a central inverter).

I also am not sold on copper/indium (CIGS) or other newer technology thin film panels and prefer conventional silicon, either moncrystaline or amorphous. Silcon panels have been around for 40 years and they have a known life, not so for CIGS. Dont worry about panel efficiency unless you have limited roof space.

You may want to talk to them about doing some parts of the installation that is a PITA for them. One thing is to consider running the metal conduit from the attic to the basement. They can run it outside the house but most homeowners want it out of sight so if you do the dirty work they should be able to give you a credit.I wouldnt take responsibility for the roof penetrations but I would aks a lot of questions on what system they use. Anysystem that is dependent upon "gunk" to seal the roof is not going to last and getting new gunk in place after the panels are installed is diffucult if not impossible.

One last thing before pulling the trigger is I assume you have gone the electrcial energy savings route? You generally have far better return on investment by reducing your load than installing PV.

 

[Vic99]

Yes, I think I'm pretty conservative with electricity. CFLs, energy star appliances, good habits, etc.

Sunpower is the brand that both Revision and the other two companies have mentioned quite a bit. Revision mentioned those AC panels to me:
http://us.sunpowercorp.com/homes/products-services/solar-panels/AC-home-solar-panel/

They are coming out to do a site evaluation early next week. The sales person on the phone seemed pretty knowledgeable.

Both of the other companies that I got quotes from said that they do not subcontract. Not sure about Revision.

I have now talked to 2 people with the maximizers. You can remotely monitor them. Although both of these guys are happy with them (one was an engineer, I think). Microinverters do seem the way to go if I can fit enough panels on good sun areas on the roof.

 

[peakbagger]

Cool, I figured so, but these days some folks do it backwards.

The sunpower panels look good, monocrystaline panels are the highest affordable efficiency. Barring going to very expensive technologies, you cant get much higher output per square foot.

Some folks try to tweak them a bit by going with taller mounting brackets to get more air flow underneath but I would stick with whatever racks they will warantee.

 

[DaveH9]

That is a awsome system, just a few comments, since you asked.

seems like you are buying more than you need, ok in MA, but in CT we can't get a rebate for anything over what we consume. I never suggest anyone spend more to overproduce. The cool thing about PV is you can add on later when you get your EV.

Do you need to upgrade to 200 amp service? If not, you could do a line side splice and keep the existing service. This could save you a grand.

The thing about the larger modules is that they do not fit on the roof as well, meaning sometimes you could get more KW on the same roof with smaller dimensioned modules. The best prices lately are for the 240 watt size, I'm not talking Sunpower. The folks that i have dealt with that went Sunpower are 2 types, some want the most powerful modules and are willing to pay a higher price per watt for that, others have a small roof and getting the most from it makes it worth doing.

You might want to look at a system with a standard module and a micro inverter, or a power one mppt string inverter. You might even be able to use 2 3000 watt inverters, one for each roof, that could be the most cost effective solution. Every PV system is designed for the location, so what they are selling you might be the best solution, just seems like lots of bells and whistles to me.

 

[Slow1]

I would go with a system like Solar City has, and just pay the lower utility bills to them. That way to do not have to pay for anything and get savings from day one. You also do not have to do very much and they pay for the upkeep over time. 22 grand is a large output for solar that far north and 10 years is a long time to recover your costs. Another issue besides inverters failing is that the panels start to decline in output from day one. Over time they produce less and less energy. Many times these systems are obsolete by the time they are paid for.

And no, I do not work for Solar City, or any utility company (I am an electrical engineer though). I am just referencing Solar City as an example of a typical solar lease system that is common here in the PNW.

The game is a bit different here in MA. Our SREC system has been designed such that we have a guaranteed floor and the high end is extremely likely to hold for a few years. Thus, even with the low end (the net $270/Mwh generated) the payback times are reduced tremendously. As a case in point here with this system - generating 5.5 SREC/year will likely bring in between $1600-2700/year in SREC revenue on top of the approx $1k in power (we pay about $0.15/kwh here). So that is how we can end up with systems that have a reasonable payback (less than 10 years). The SRECs continue to pay for 10 years - so that can more than cover maintenance costs. If you lease all this goes to the leasing company - they are more than happy to take it of course.

Most of the panels have warranties (take that for what it is worth) that state 80% of rated power in year 25. I don't know how well they will hit that, but I imagine it will be somewhat close if not better than this. So while it is factual that there will be losses in production over time, I don't anticipate this will have a material affect in the first 10-15 years. I can't seriously believe that this will be the factor making the PV array obsolete within 10 years. Granted there are likely to be new/better systems available, but as I tell folks with computers who compulsively upgrade - just because there is a new/faster/lighter computer out doesn't make the current one any less functional.

 

[StihlHead]

The game is a bit different here in MA. Our SREC system has been designed such that we have a guaranteed floor and the high end is extremely likely to hold for a few years. Thus, even with the low end (the net $270/Mwh generated) the payback times are reduced tremendously. As a case in point here with this system - generating 5.5 SREC/year will likely bring in between $1600-2700/year in SREC revenue on top of the approx $1k in power (we pay about $0.15/kwh here). So that is how we can end up with systems that have a reasonable payback (less than 10 years). The SRECs continue to pay for 10 years - so that can more than cover maintenance costs. If you lease all this goes to the leasing company - they are more than happy to take it of course.

Well, when you are talking numbers like $22 grand, I would rather rent the systems myself and just pay less per month for electricity. $22 grand is a lot of dough, even with all the subsidies. I am not a big fan of home-subsidised electric generation, and that can all change with a different political party being voted in place, or law being changed. We pay 10 cents a KWh here, cheaper rates with 30% hydro and lots of rain lately. I do not use enough electricity to make any of these worth my while, really. They cap the size of your system here to the amount that you use. You cannot become a large generating station, per se. Otherwise I would put up panels on an acre here and retire selling power to the grid.

We will see how long these systems last over time. I have been designing electronic systems and microchips for a long time, and I used to work in a failure analysis lab. This year's craze in industry are often times next year's failure and disaster. Most panel components are made in China. Look at the huge problems with the building materials coming out of there, um.... like sheetrock. Also look at the rate of bankruptcies in solar companies lately. What do you do with equipment and a warantee from a company that is no longer in business? Also I am considering the real payback time on these systems, not the subsidised ones.

Its all a political shell game, and a high price for electricity paid out in the end. Certainly there needs to be more energy production locally, but... I believe we have far outpaced our ability to keep pace with US and global population demands, given the resources that we have.