Rooftop solar experiences in TX

[zwede]

I'm considering getting a 5kW system for my house, but there're so many products out there and lots of installers. Wondering if anyone has had it done here in TX and your experience with it. How did the install work out, any unforeseen costs, performance, issues...

So far I have 2 quotes:

[SIZE=-1]20x CentroSolar E250B panels with a single SMA SB5000US inverter. Net after $4K tax credit and $1K utility co incentive: [/SIZE]$8,750.

20x Renesola JC255M-24/Bx panels and 20x Enphase M215-60-2LL-S2x inverters. Net after $4K tax credit and $1K utility co incentive: $8,450.

Which one is the better system? The Enphase microinverter seems cool as the inverters are mounted under each panel (no box in the garage). But are they good?

Update 06/18/2014: Have solar now, see post #6

 

[BerTX]

Is the size of the system due to the amount of space you have available for panels? If there is a possibility that you will be adding on, the microinverter has definite advantages. You will also be a little safer with 240 volt AC running through your wires, rather than 5-600 volt DC. If (once out of warranty) an inverter has a problem, it will be much cheaper to replace a microinverter.

The microinverter SYSTEM is more reliable. If an inverter malfunctions your system will continue to function, minus the input of the one panel. Likewise, if a panel goes out or is damaged, the remaining panels will continue to function. With a single inverter, a single panel can put the entire system out, depending on the configuration.

In my case, I do not have my panels on the roof, and I have room for expansion. I have a single inverter (SB8000US), and I sized it to allow for future expansion. However, due to the requirements of the inverter, I have a very limited number of options to expand, because the specific panels I have are no longer manufactured, and they all need to be of matching characteristics. I will want to expand, but I will likely have to increase my system by 30% when I do expand. If I had microinverters I'd be able to expand piecemeal if desired.

That being said, I have no direct experience with Enphase but I have heard nothing bad as far as reliability. I can say that the Sunny Boy has not missed a lick in 2 years.

If I were buying a new system in MY situation, and the cost were similar between the two, I would buy the Enphase. The prices at the time I did my system were not anywhere near comparable. However, I did my own installation -- some of the savings in the Enphase quote might be in lower installation cost. 70% of what YOU are paying is installation cost...

 

[zwede]

The size of the system is because my utility (CoServ) does net metering but they do not purchase excess power. So if at the end of the month I have produced more than I have consumed I will have given them the excess for free.

I like the idea of a future expansion. CoServ may well start paying for extra production, and I could then simply add a few more panels.

The enphase quote has a discounted labor cost as that installer seems to want the job more. The equipment cost is higher for the enphase system.

 

[jeremyz]

I've had Enphase microinverters for about 2.5 years. So far, I have no complaints. When I got my system, the only advantage that monolithic inverters could boast was a lower price. If the price for micro-inverters is lower, I would say it's a no-brainer to get them. I can confirm all of the benefits that BerTX mentioned and also add in that micro-inverters are much better if you have any kind of shade issues. I have a couple of panels that get some shade during part of the day during certain parts of the year. With a monolithic inverter, the whole array's power production would be crippled. With the micro-inverter, only the affected panels see a reduction in power generation.

 

[BerTX]

Exactly my utility situation when I sized my system, and now my utility has switched away from net metering (although I am grandfathered and have the option to change if I want to). They pay for the excess power produced in a given month, BUT they pay the wholesale price, not the retail price. My per kWh price is 8.8¢, and the wholesale price is 5.6¢, and my utility charges me $25/month "availability charge" even if I use no power at all.

If I increase the size of the system, it could make enough to pay the "availability charge", and I would truly have zero cost, rather than the $300 I pay now.

Anyway, it all becomes very complicated in the calculations, but it seems that right now, in my current situation, I just about come out the same either way I choose to go. I decided to let it ride with the net metering for now.

 

[zwede]

Update: Went with the Enphase microinverter solution, 20x 250W PhonoSolar panels. Flipped the switch last night. Of course today is cloudy! Still early, but it has a peak of 4.35 kW (despite haze/clouds), and by 2 pm it has produced 14.5 kWh. I'm hoping for 30+ kWh/day on sunny days in July and August. That would cancel most of my electrical bill.

Here's public access to my system:

Markus 5kW

 

[Shaggy]

I've had my SunPower with SunnyBoy system running about 4 months. I bought a 100% replacement system (sized to replace 100%). I'm running a surplus and Austin Energy buys and credits to my bill all production minus my usage. I won't ever get a check, but then I'll never write them one either... Austin Energy runs the EV chargers in town so the $25 fee I pay comes out of my electric bill, where I have a surplus, so all of my driving around town is free.

I have a 6.54 KW setup of 20 SunPower e20 327vt panels. It's so far been hassle free.

 

[gizmoboy]

Update: Went with the Enphase microinverter solution, 20x 250W PhonoSolar panels. Flipped the switch last night. Of course today is cloudy! Still early, but it has a peak of 4.35 kW (despite haze/clouds), and by 2 pm it has produced 14.5 kWh. I'm hoping for 30+ kWh/day on sunny days in July and August. That would cancel most of my electrical bill.

Here's public access to my system:

Markus 5kW

Out of curiosity, did you consider options from the likes of SolarCity?

 

[jerry33]

Out of curiosity, did you consider options from the likes of SolarCity?

Good luck on that one. If they will do it (and they seem to have all kinds of reasons why they won't) they want the 25 year lease payment up front. Solar City appears to be geared for California only.

 

[harry]

There is another option, besides a string inverter or microinverters. Solar Edge has a kind of hybrid system which consists of "power optimizers" which assure that each panel is at its maximum power point at all times, and a simple inverter that handles the DC output from the optimizers to provide house power. The optimizers have the same advantages as the microinverters, but unlike an earlier poster, I feel that high voltage DC is safer than a whole string of 120V AC lines running through the array. Like the microinverter system, you can add panels of different brands, wattages, etc, with no problem. We have had a 33Kw system running for two years (144 panels) and have had only one optimizer failure,covered by the Solar Edge 25 year warranty. That's 99.3% reliability so far. The system was less expensive than an Enphase setup, but that cost comparison can change based on the total number of panels in a system. The web based monitoring with Solar Edge is very slick and provides real time info on the entire system at the panel level and up to the entire system performance. (Enphase also has a nice monitoring system.)

I would caution that panels feeding directly into a string inverter are subject to substantial losses in production if one or more panels is producing less than others (small clouds, shade, etc). In that case the remaining panels will try to equalize the power output by feeding some of their power to the weak-producing panels. Think of a bunch of water buckets connected across their bottoms -- water is going to flow through the buckets until the level is equal in all the buckets. Unfortunately, to that extent the flow is not providing power to you.

 

[gizmoboy]

Good luck on that one. If they will do it (and they seem to have all kinds of reasons why they won't) they want the 25 year lease payment up front. Solar City appears to be geared for California only.

They proposed doing a setup for my house, but could only provide about half the power we typically use (our household is apparently a major energy hog, rolling 3-6K Kwh per month), and they now offer options like no up front payments, but fixes power at something like 0.11 per Kwh for the life of the lease.