AC Solar Panels

I've been looking into getting a solar system for our house and the recently introduced AC panels seem like the best option. I am wondering if anyone has any advice.

It seems like the two options I have would be getting either 17 square foot inexpensive ones for about $500 or 13 square foot sunpower ones that come out this month and will likely cost a few hundred more. They all seem to output 225 watts AC. I have a tiled roof so self installation unfortunately isn't an option but if anyone knows of a guide for setting up AC solar panel systems I'd very much appreciate having a look at it. Thanks

coolfilmaker said:

I've been looking into getting a solar system for our house and the recently introduced AC panels seem like the best option. I am wondering if anyone has any advice.

It seems like the two options I have would be getting either 17 square foot inexpensive ones for about $500 or 13 square foot sunpower ones that come out this month and will likely cost a few hundred more. They all seem to output 225 watts AC. I have a tiled roof so self installation unfortunately isn't an option but if anyone knows of a guide for setting up AC solar panel systems I'd very much appreciate having a look at it. Thanks

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The 'A/C' Solar Panels are not actually A/C panels. They are D/C Panels with an integrated Micro-Inverter. The micro-inverter option has been available for quite some time.

Panels typically last 20-25 years. Inverters typically last 10-15 years. I would prefer my inverter to go in a single instance, not sporatically over time. Micro-Inverters (or Tigo Maximizers) are preferable in instances of shading or other types of obstructions. If no obstructions, no need for Micro-Inverter.

That's just one person's option.

BTW - My system consists of 30 Sunpower 230w Panels + 1 Sunpower 7kw Inverter (SMA) + Tigo Maximizers (primarily for monitoring purposes).

Yeah I know all about the specificities. Thanks for the advice about inverters, I'm guessing that they've figured out how to make them last a bit longer by now. It looks like there have been some articles recently about longer lifespan inverters. My bet is that they're making AC panels now because they've made micro inverters that do last 25 years. I also think that they give you a few percent more efficient conversion and a much easier installation. We don't really have an ideal location to place an inverter on the route to our breaker panel.

I think my only hesitation is caused by the fact that nothing in our house ultimately runs on alternating current!

SilverLeaf said:

Inverters typically last 10-15 years.

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A large central inverter has an MTBF around 10 years while a microinverter has an MTBF over 300 years and a life expectancy over 30. The conclusion is that you have to buy and install three central inverters to get a 25-year life while a microinverter system will be maintenance free the entire time. In 25 years, you may lose 2 microinverters and 1 PV panel, so you would still have 90% of your system functional after 25 years, even if you did no warranty replacements.

SilverLeaf said:

I would prefer my inverter to go in a single instance, not sporatically over time.

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Not me.

coolfilmaker said:

Thanks for the advice about inverters, I'm guessing that they've figured out how to make them last a bit longer by now. It looks like there have been some articles recently about longer lifespan inverters. My bet is that they're making AC panels now because they've made micro inverters that do last 25 years.

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Right. In fact, the warranty now gives 25 years, just like the panels.

coolfilmaker said:

I also think that they give you a few percent more efficient conversion and a much easier installation.

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I also think they are safer since you do not have the high-voltage DC loops.

coolfilmaker said:

I think my only hesitation is caused by the fact that nothing in our house ultimately runs on alternating current!

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That could be an issue if you want to net meter. There's generally not much benefit to produce more than you use. If this is for a LEAF, then I would size the system accordingly.

Sorry, I don't have any experience installing on a clay roof.

I was just joking about our house running on DC because our Leaf, LED lights, TV, computers, etc. all use AC to DC converters.

coolfilmaker said:

I was just joking about our house running on DC because our Leaf, LED lights, TV, computers, etc. all use AC to DC converters.

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I thought that might be it, but then I reread what you wrote and thought "Nah! He's off-grid with most of his loads!" Thanks for clearing that up!

Have a quote for 6.44 KW system that utilizes AC PV modules. The panels are from NESL (Nexus Energy solutions) co-designed with Solarbridge (Austin based startup). No micro inverter needed as it is integrated into the panel.

Cost is $1.60 per watt (after Austin Energy rebates and the estimated Federal incentives). Ran Sunmath and the ROI is 8 years.

This was our third design coming in after (1) the traditional design with the central inverter (2) with Enphase microinverter. The geek in me wants to be one of the early adopters.

Wondering if anyone else is familiar with an integrated design (not Enphase). Thanks..

SilverLeaf said:

Panels typically last 20-25 years. Inverters typically last 10-15 years. I would prefer my inverter to go in a single instance, not sporatically over time. Micro-Inverters (or Tigo Maximizers) are preferable in instances of shading or other types of obstructions. If no obstructions, no need for Micro-Inverter.

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Certainly not a "need" but they have a lot of advantages. Enphase specifically is warranted for 25 years with a 100% up time guarantee. So they'll replace a failed inverter, pay to have it installed, and pay for the lost production. Will your central inverter manufacturer do that? When something does go wrong instead of your entire system going down you just loose a panel.

Even in non-shade instances. Do all the panels output the exact same amount? Do they all age at the same rate? Does soiling happen evenly? Sure we aren't talking big numbers but

Being able to see per panel statistics is amazing. Would you even know if a panel failed? What if a panel failed in a way that took out the whole array. That sure wouldn't be fun to troubleshoot.

It seems that the efficiency ratings of the microinverters are often higher.

Doing it DIY dealing only with AC makes the system sooo much easier to design and install. Probably not the case for a professional.

Central inverters can be noisy, having them somewhere where you can hear them isn't pleasant.

Central inverters are big and bulky and need somewhere to go.

When you want to add more panels in the future it's likely to be much easier with micro inverters.

When you have multiple roofs at different angles, designing a central inverter based system can get trickier.

I think it's definitely obvious that microinverters are safer. With central inverters you have always live (in the sun) high voltage DC going from the roof to the inverter. I hear some jurisdictions require a disconnect on the roof.

There's a lot more rules when working with DC that to me seemed more difficult to get a grasp of compared to AC.

For small arrays microinverters will be cheaper. Obviously as you get larger and larger that gap goes the other way, but if you get too large then you need two inverters and they are cheaper again.

Anyway, that's my brain dump of why I like microinverters

If the Enphase M215 wasn't available when you got your tigos I can see why you made that decision though.

pjoseph said:

No micro inverter needed as it is integrated into the panel.

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What do you mean not needed? That's like saying the LEAF does't need a battery because it's integrated into the automobile?

I have never compared Solarbridge to Enpahse. Where they really selling back in late summer of 2011? If I had heard of them they didn't even make it on my radar to compare. But my gut reaction is Enphase has a lot more experience in this area.

My assessment of these "AC Panels" is they are not much to get excited about. As far as I can see the only real benefit that they MIGHT be able to offer is cheaper material cost and cheaper install cost. With Enphase you have to consider the mounting of the inverter to your rack and the grounding of the inverter. This requires a little bit of extra hardware, planning, and install time. With the "AC Panels" that part of the process is done already. I'm not seeing any technology innovation here. It's just shifting some labor from the roof to the factory.

I suspect what is going to happen though is there is going to be a premium charged for this. The other issue is you can't pick out the cheapest PV panel. You are stuck picking from the manufacturers who have signed up to integrate these.

pjoseph said:

Wondering if anyone else is familiar with an integrated design (not Enphase).

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I think the question you should be really asking is anyone familiar with SolarBridge. The integrated design doesn't change anything except the process to install it. It's not even "integrated". The only difference is it's mounted to the frame of the panel instead of to the racking and done at the factory.

What was the cost difference between your three quotes?

coolfilmaker said:

It seems like the two options I have would be getting either 17 square foot inexpensive ones for about $500 or 13 square foot sunpower ones that come out this month and will likely cost a few hundred more.

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That's a bizarre way to think about the cost of panels. The number I want to see is cost/DC watt rating.

QueenBee said:

pjoseph said:

Wondering if anyone else is familiar with an integrated design (not Enphase).

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I think the question you should be really asking is anyone familiar with SolarBridge. The integrated design doesn't change anything except the process to install it. It's not even "integrated". The only difference is it's mounted to the frame of the panel instead of to the racking and done at the factory.

What was the cost difference between your three quotes?

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Thanks for your response. Yes, the Solarbridge product is integrated into the panels. It is brand new and that's why it was not on your radar last year. Yes, it limits the choice of panel vendors. Yes, it simplifies installation greatly. There is a webinar this afternoon.

The quotes (after Austin Energy rebates and Federal incentives) on a 6.44 KW system were as follows (turnkey installation includes permits & warranty)
1) Central Inverter: $1.21 per watt (received comparable quotes from multiple Solar installers)
2) Enphase: $1.64
3) Solarbridge: $1.60

These are among the best numbers i've seen anywhere (primarily because Austin Energy has a rebate of up to $15,000 per year).

It's true that Enphase has been around longer than Solarbridge. But if i wanted to buy a car with that logic, should i go with GM? :mrgreen:

QueenBee said:

Certainly not a "need" but they have a lot of advantages. Enphase specifically is warranted for 25 years with a 100% up time guarantee. So they'll replace a failed inverter, pay to have it installed, and pay for the lost production. Will your central inverter manufacturer do that? When something does go wrong instead of your entire system going down you just loose a panel.

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Are you affiliated in any way with any solar equipment manufacturer or supplier?

Tuned in to the webinar. One major takeaway is that
AC module != solar panel + microinverter

It is sold as one system and warrantied by the panel vendor. Cabling is greatly simplified as is installation.

The Solarbridge system should be installed on our roof as soon as the logistics are cleared. This is bleeding edge technology and i am willing to live with the bumpy ride to reap the benefits. Same philosophy as buying the Leaf.

I equate the AC panel to a cell phone that I can't exchange the battery in. I normally prefer to take chances on new technology also but the advantages I feel are like purchasing a remote control and the manufacturer has installed the battery for me, nice but your going to charge me extra for something i could have done in 30 seconds? Installing my 28 enphase micro inverters took maybe 1 hour to complete? And if your not doing a self install why would you care that your installer was able to install in 1 less hour especially if it costed more? In actuality you are paying the AC panel manufacturer for a panel, micro-inverter, and custom enclosure under the panel to make it look built-in when you are never going to look at the bottom of the panels ever again (unless you are installing the panels over your glass roof). I don't see the value and/or flexibility.

pjoseph said:

It's true that Enphase has been around longer than Solarbridge. But if i wanted to buy a car with that logic, should i go with GM? :mrgreen:

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Maybe if GM had an all EV ;P That's some awesome prices. So what was the cost per watt DC before the rebates? You'd have to be crazy to not be installing home PV if you live in Austin! So how many years before you break even?

pjoseph said:

AC module != solar panel + microinverter It is sold as one system and warrantied by the panel vendor. Cabling is greatly simplified as is installation.

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Sad that I missed it, would have been interesting. So exactly how is the cabling simplified? To me it literally looked the same as Enphase except it came pre-installed on the panel. Obviously there are less steps to installation which is good but nothing to get excited about. It's really interesting that it gets warrantied by the panel manufacturer. I'm surprised they would want to take on that since it's outside their core business of making panels. What brand panels did you get? At least this means you don't have to be as concerned if Solarbridge goes under, assuming the panel manufacturer doesn't

AndyH said:

Are you affiliated in any way with any solar equipment manufacturer or supplier?

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Only in that I have self installed Enphase M215's and Canadian Solar panels on my roof.

lipower said:

I equate the AC panel to a cell phone that I can't exchange the battery in.

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I agree except that I assume this doesn't make it any more difficult to service the micro inverter. I would assume that if one fails you don't have to send the panel in so the micro inverter is a field serviceable unit. Apparently the hardware is cheaper and/or the installer is reducing their labor cost in his case but for me personally I'd pay the extra 2.5% to get Enphase which I would consider a known product vs. SolarBridge who basically just is a clone except they'll bolt it on to the panel for you.

In any case, wooo to more home solar! Congrats!

pjoseph said:

The quotes (after Austin Energy rebates and Federal incentives) on a 6.44 KW system were as follows (turnkey installation includes permits & warranty)
1) Central Inverter: $1.21 per watt (received comparable quotes from multiple Solar installers)
2) Enphase: $1.64
3) Solarbridge: $1.60

These are among the best numbers i've seen anywhere (primarily because Austin Energy has a rebate of up to $15,000 per year).

It's true that Enphase has been around longer than Solarbridge. But if i wanted to buy a car with that logic, should i go with GM? :mrgreen:

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Hello. I got a 21-panel Enphase M215 system installed this spring in Austin for $4.26/W (before rebates), about $1.30/W after rebates. I'm guessing the extra cost you quote above is because of the reduced AE rebate (from $2.50/W to $2/W)? Bummer they lowered the rebate, but at least they kept the max rebate amount the same. I'm looking forward to the increased payback amount starting in October.

While I do have Enphase one advantage I has read about the Solarbridge product is that it doesn't use electrolytic capacitors, while the Enphase does. But both have 25-yr warranties so not sure how much that really matters. The integrated AC panels using the Solarbridge micro weren't around when I started getting quotes in the winter. --- Actually did find a quote using a SB micro in my e-mails, but it was $1000 higher than the Enphase quote.

Did you get a quote from SRE? They were my installed and did a pretty good job.

edited to correct after rebate cost

Jclimber99, Thank you for that update. Our system is getting installed this week. First Solarbridge installation in the Austin area, AFAIK. Our installer is Texas Solar power company and they have done large commercial installations. They are excited about Solarbridge because it greatly simplifies wiring and interconnects.

Austin Energy rates are going up and will be tiered starting October 1st. We are also moving from net to gross metering. Yes, the rebate is down $0.50 per watt to the current rate of $2 per watt*. Even then, the rate increase has perked people up. Two other installations went up on my street in the past 2 weeks.

As a long term investment, this looks like a no-brainer.

* For some historical perspective, 5 years ago the rebate was $5 per watt (cost before rebate was $7 per watt). This little tidbit from my project manager.

pjoseph said:

Jclimber99, Thank you for that update. Our system is getting installed this week. First Solarbridge installation in the Austin area, AFAIK. Our installer is Texas Solar power company and they have done large commercial installations. They are excited about Solarbridge because it greatly simplifies wiring and interconnects.

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Cool, I'm sure you are going to love it! I also got a quote from TXSPC but they would only put panels on my roof where was no shading, even though I asked for a system with microinverters. If there is no shading then the benefits from using micros aren't as compelling. I think they doubted the system would get approved by AE. But SRE put panels on the entire south-facing roof and I had no issues getting approvals from AE.

Yup, rates are going up. But we typically use between 350 kwh (winter) to 920 kwh (summer peak) per month (average before pv installed) so our rate increase is pretty minimal.

pjoseph said:

Yes, the Solarbridge product is integrated into the panels. It is brand new and that's why it was not on your radar last year. Yes, it limits the choice of panel vendors. Yes, it simplifies installation greatly.

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Thanks for the heads up on SolarBridge, pjoseph! I'm glad to see that there is competition for Enphase in the market. Competition benefits the consumers, but it will also help both manufacturers focus on advancing their products and business models. I wish both companies long-term success!

I also like the idea of eliminating the electrolytic capacitors. That has always been a concern for the Enphase units. That said, it takes a lot more than higher-performance components to achieve the type of MTBF numbers that Enphase has achieved. Hopefully SolarBridge is up to the task!

jclimber99 said:

[ But SRE put panels on the entire south-facing roof and I had no issues getting approvals from AE.

Yup, rates are going up. But we typically use between 350 kwh (winter) to 920 kwh (summer peak) per month (average before pv installed) so our rate increase is pretty minimal.

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Our PV will be on the south-facing roof as well. No shading issues for us. One of my neighbors has their new array on the west facing roof and another has it facing east. This appears an inexact science and every installer goes with their own design philosophy.

Most people go with the cheapest cost per watt (it is the sun producing energy after all). My reasoning is similar to that of buying an upscale car. Paying a pretty penny for the geek factor.

Your energy consumption numbers are very modest. Based on gross metering, the new 12.8 c payout per KWh should be good for you.

We have a Texas sized home (3,500 sq ft, well insulated, builder was first owner) and a monthly average consumption of 1,518 KWh. And that includes the Leaf drawing 400 KWh (to drive an average of 1,600 miles per month). Our system will initially be 6.44 KW.

RegGuheert, Appreciate you sharing your Enphase production data. They are clearly ahead in the data presentation arena.

pjoseph said:

jclimber99 said:

Yup, rates are going up. But we typically use between 350 kwh (winter) to 920 kwh (summer peak) per month (average before pv installed) so our rate increase is pretty minimal.

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Your energy consumption numbers are very modest. Based on gross metering, the new 12.8 c payout per KWh should be good for you.

We have a Texas sized home (3,500 sq ft, well insulated, builder was first owner) and a monthly average consumption of 1,518 KWh. And that includes the Leaf drawing 400 KWh (to drive an average of 1,600 miles per month). Our system will initially be 6.44 KW.

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Our house is 1500 sq ft, single-story, 16 seer two-stage a/c, attic re-insulated & all ducts replaced 3 yrs ago. Our energy numbers would be even lower but I have a pond pump & uv light running 24/7.

pjoseph said:

Our PV will be on the south-facing roof as well. No shading issues for us. One of my neighbors has their new array on the west facing roof and another has it facing east. This appears an inexact science and every installer goes with their own design philosophy.

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According to PVWatts, placing the panels on the East-facing roof of our house only results in about 14% less energy collection over the course of a year versus the nearly-ideal South-facing roof we used. But I will point out that PVWatts doesn't tell the entire story since it does not differentiate production throughout the day. I remember reading that Solar Guppy in Florida has found that putting the panels on the East-facing roof down there results in MORE production than using a South-facing roof due to the frequent thunderstorms in the afternoons.

pjoseph said:

RegGuheert, Appreciate you sharing your Enphase production data. They are clearly ahead in the data presentation arena.

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You're welcome! You will find a few other Enphase systems in signatures on this site.

Please note that what you see today when you click on the link in my signature is the OLD Enlighten website. Those of us with systems have preview access to the new HTML5 site which has a few additional features. Frankly, I like the look of the array on the old site, but that's a minor detail. The new site should be live very soon. Check back in a few days if you would like to see it.