Solar Edge Vs Enphase Power optimizers

[cebury]

Rarely will anyone be forced to bring up an existing electrical system to meet the current code. It is only when that existing system is modified or changed that the latest code requirements need to be met.

Although there are some areas of building codes that require existing facilities to be updated. Due to new hires some buildings must meet the new ADA code to allow safe and easy passage (including restrooms) for people that require wheel chairs.

I assumed that. But that's dangerous to do in CA with code or laws. These days, you just never know when/where the political will falls into those OMG exceptions. If CA was leaning the retrofit direction I'm sure you folks would've heard of it by now.

Thanks for the answer.

[solarix]

Basically, we in the solar industry are bucking the system trying to make electricity flow backwards through the grid. The whole electric system is not set up for this either physic-ally or business-wise, or code-wise. There are lots of challenges to getting the electric system to be more clean/renewable/resilient, so we just keep pushing through all the high-seas and hoping the tide will turn.

[lanb]

Rapid shutdown with string

If for some reason (code or future modification of system), rapid shutdown needs to be installed on an existing string system.

Will something like SMA_Rapid_Shutdown do the trick ? How difficult and expensive would it be to retrofit this ?

Does it make sense to have this now in anticipation of NEC 2014 ? The doc talks about savings in lieu of a junction box.

[inetdog]

If for some reason (code or future modification of system), rapid shutdown needs to be installed on an existing string system.

Will something like SMA_Rapid_Shutdown do the trick ? How difficult and expensive would it be to retrofit this ?

Does it make sense to have this now in anticipation of NEC 2014 ? The doc talks about savings in lieu of a junction box.

That should work and the necessary comm wiring should be inexpensive. Either as a marketing decision or a hardware dependency it will only be offered to work with units that have the SPS option already.

[SunEagle]

If for some reason (code or future modification of system), rapid shutdown needs to be installed on an existing string system.

Will something like SMA_Rapid_Shutdown do the trick ? How difficult and expensive would it be to retrofit this ?

Does it make sense to have this now in anticipation of NEC 2014 ? The doc talks about savings in lieu of a junction box.

I am sure that existing string inverter manufacturers as well as other solar equipment companies will develop a device that can be easily field installed that would meet the NEC 2014 rapid shutdown requirement.

The key is to reduce the voltage being generated by the panels to below 50v within 10 feet of the array. I do not believe installing a device like that would be costly.

[ButchDeal]

I am sure that existing string inverter manufacturers as well as other solar equipment companies will develop a device that can be easily field installed that would meet the NEC 2014 rapid shutdown requirement.

The key is to reduce the voltage being generated by the panels to below 50v within 10 feet of the array. I do not believe installing a device like that would be costly.

the existing systems for this are not cheap.
you need a controller and the disconnect devices:

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=44&productCatName=RAPID-SHUTDOWN-SYSTEM-NEC-690.12

The disconnect devices often double as combiners but are more expensive than standard combiners.

http://www.midnitesolar.com/pdfs/rapidShutdown11x17_frontBack.pdf

Fronius is working on their own device as well:

http://www.fronius.com/cps/rde/xbcr/SID-FDAC8843-5B285C5C/fronius_usa/RapidShutdownBox_441527_snapshot.pdf

few of these systems seem to be available at this time. There may be a cheaper solution in the future.

[SunEagle]

the existing systems for this are not cheap.
you need a controller and the disconnect devices:

http://www.midnitesolar.com/products.php?menuItem=products&productCat_ID=44&productCatName=RAPID-SHUTDOWN-SYSTEM-NEC-690.12

The disconnect devices often double as combiners but are more expensive than standard combiners.

http://www.midnitesolar.com/pdfs/rapidShutdown11x17_frontBack.pdf

Fronius is working on their own device as well:

http://www.fronius.com/cps/rde/xbcr/SID-FDAC8843-5B285C5C/fronius_usa/RapidShutdownBox_441527_snapshot.pdf

few of these systems seem to be available at this time. There may be a cheaper solution in the future.

I guess it is a matter of judgement about what is low cost and what is not.

IMO a single device like the Midnitesolar Birdhouse would be cheaper to install then installing a device (similar to a micro inverter) at each pv panel. Maybe Fronius will deliver their product at a reasonable cost.

If the string inverter manufacturers want to help people upgrade their system to meet the new NEC requirement IMO it can lead to a price war with 3rd party companies providing a UL listed device to do what is needed without the need to purchase from the string inverter mfg.

[ButchDeal]

I guess it is a matter of judgement about what is low cost and what is not.

IMO a single device like the Midnitesolar Birdhouse would be cheaper to install then installing a device (similar to a micro inverter) at each pv panel. Maybe Fronius will deliver their product at a reasonable cost.

If the string inverter manufacturers want to help people upgrade their system to meet the new NEC requirement IMO it can lead to a price war with 3rd party companies providing a UL listed device to do what is needed without the need to purchase from the string inverter mfg.

Bird house isn't a single device. You have to ADD birdhouse compatible combiners to do the disconnecting (even if combiners are not needed), additional wiring that is required adds cost and labor as well.

Optimizers are much simpler to install and for almost every system size we have found equipment for SolarEdge cheaper than string inverter with rapid shutdown compliance (including labor differences). The only exception is for systems under 8 modules, in which case enphase.

Fronius and SMA MIGHT come out with something cheaper and simpler to install (wire line communications, and inverter controlled instead of separate control unit) but they are not available yet. Even then I would expect the costs to just be closer

[SunEagle]

Bird house isn't a single device. You have to ADD birdhouse compatible combiners to do the disconnecting (even if combiners are not needed), additional wiring that is required adds cost and labor as well.

Optimizers are much simpler to install and for almost every system size we have found equipment for SolarEdge cheaper than string inverter with rapid shutdown compliance (including labor differences). The only exception is for systems under 8 modules, in which case enphase.

Fronius and SMA MIGHT come out with something cheaper and simpler to install (wire line communications, and inverter controlled instead of separate control unit) but they are not available yet. Even then I would expect the costs to just be closer

I stand corrected. Thanks for the real life info on that equipment.

[lanb]

Is the SMA rapid shutdown box not yet available ?

According to sma-strengthens-sunny-boy-tl-us-series-two-new-solar-models , it was supposed to be available in early 2015.

[solar_newbie]

One thing I would see is Enphase is good if someone plan to add additional panels by themselves later which I plan to do ... Power company allow up to 1KW system to add on without impact the NEM 1.0 contract. Since they count only AC system, I would be able to add 4 more 260-280w panels with 250w inverter. Those panels can be added anywhere or just build a simple rack or poll for them and connectivity is much simple with just AC wire directly to your electric sub-panel.

If adding more panels into either SolarEdge and SMA, 4 panels is too low for a new inverter. Adding into existing string and inverter will require the old company to come back and charge all labor cost. Labor cost for a small system is very high... If adding more than 4 panels, you will be automatically get out of NEM 1.0 which is locked for 20 years. If adding to existing string without the old installer to do it, you lose your warranty.

Beside that 3 options are almost the same and having pros/cons in different situations.

[sensij]

I think it is premature to speculate too heavily on how additions / modifications to installed arrays will be handled once NEM 2.0 kicks in. The current guidance is that modifications increasing AC capacity by 1 kW or 10% (whichever is less) will be allowed without requiring a new interconnect agreement, and that increases in capacity over that will not jeopardize the NEM 1.0 status of the original array; only the expansion will be subject to the new rules. I don't see a simple way for them to implement that guidance, however, and against a backdrop of changing regulations (rapid shutdown, and eventually, smart grid interactive features), it is hard to know what the final list of requirements will be for an array expansion.

Enphase, in particular, is not necessarily any easier (or more difficult) to expand. Keep in mind that the maximum number of M250's that can go in a string is 16, so if you are already close to that limit, you'll be looking at combiners, a new or larger PV breaker, and possibly new wiring. If you are already at the 120% limit for the busbar, a panel upgrade could become necessary. If you plan for capacity increase in advance, some of that can be avoided, but the same can be said for other types of inverters as well. What is simpler than just adding another panel to a series string, if its electrical specs are right and the inverter can handle the additional voltage?

Increasing capacity in the future is a sketchy proposition anyway. Why not try to size the array correctly to begin with? On average, US residential electricity consumption has been dropping, and as appliances and electrical equipment become more efficient, and home automation becomes more widespread, there is no reason for that not to continue. EV's definitely have the potential to dramatically change consumption, but most power companies offer special rates for EV charging that are low enough to make offsetting that consumption with PV barely cost-effective, if at all.

As for the warranty, it will be installer specific, and in most cases, not likely to be worth much anyway.

[donald]

............

Increasing capacity in the future is a sketchy proposition anyway. Why not try to size the array correctly to begin with? On average, US residential electricity consumption has been dropping, and as appliances and electrical equipment become more efficient, and home automation becomes more widespread, there is no reason for that not to continue. ............

In my experience, home automation increases energy consumption. With LEDs I have many lights come on automatically at sunset. I have all kinds of microprocessors and networking always running. (Wifi, zigbee, z-wave, airplay devices)

But I agree with the principal of sizing correctly for today.

[solar_newbie]

I think it is premature to speculate too heavily on how additions / modifications to installed arrays will be handled once NEM 2.0 kicks in. The current guidance is that modifications increasing AC capacity by 1 kW or 10% (whichever is less) will be allowed without requiring a new interconnect agreement, and that increases in capacity over that will not jeopardize the NEM 1.0 status of the original array; only the expansion will be subject to the new rules. I don't see a simple way for them to implement that guidance, however, and against a backdrop of changing regulations (rapid shutdown, and eventually, smart grid interactive features), it is hard to know what the final list of requirements will be for an array expansion.

I agree on this part. However for the grandfather clause, I still can follow the old rule on this current array. For example, Both of my gas and electric feed lines are next to each other. The new rule requires them to be few feet a part. If I remove or install new main panel, I must follow the new rule. If I just add or replace different breakers in the current main panel, the new rule does not apply to me as my system has grandfather clause to protect it.

Enphase, in particular, is not necessarily any easier (or more difficult) to expand. Keep in mind that the maximum number of M250's that can go in a string is 16, so if you are already close to that limit, you'll be looking at combiners, a new or larger PV breaker, and possibly new wiring. If you are already at the 120% limit for the busbar, a panel upgrade could become necessary. If you plan for capacity increase in advance, some of that can be avoided, but the same can be said for other types of inverters as well. What is simpler than just adding another panel to a series string, if its electrical specs are right and the inverter can handle the additional voltage?

Yes, it is the case where you have 16 inverters in 1 string. Why I ask an installer to use 2 strings for my 16? It is just an easy ask for the first installation.
When adding 2 strings, the busbar must be calculated to cover for 2 breakers, aka 30A or 40A more.
If an installer adds a string with 15A or 20A breaker, he must have the wire to support it or city will not sign the permit.
So, now you can easy add few more panels into the existing string without impact the warranty (Just connect to the end point of the string by plug in a new enphase cable with a join).
For compatibility, you need to make sure the new inverter has the same spec or compatible with it. All inverter should follow the same spec of the new panel and the grid. If not, I am not sure how they can sell them.

Increasing capacity in the future is a sketchy proposition anyway. Why not try to size the array correctly to begin with? On average, US residential electricity consumption has been dropping, and as appliances and electrical equipment become more efficient, and home automation becomes more widespread, there is no reason for that not to continue. EV's definitely have the potential to dramatically change consumption, but most power companies offer special rates for EV charging that are low enough to make offsetting that consumption with PV barely cost-effective, if at all.

Everyone can size the array correctly But no one will size the array for future degrade. I would assume array will degrade 0.7%-1% a year. 10 years from now, you lost up to 10% of the current calculation.
I do not think people will size array for 10% more to cover for 10 years and waste those power.
Like you said EV will make the balance change, plus the TOU will change and you need more power than you current size with even existing EV. All sizing will be toss with that.
I would foresee expansion will be necessary on most household in the future.
Most of my friends in Bay Area have solar in 2011 and now consider on add on more arrays. They did not forecast EV car by 2011 Now they need 2,000 - 3,000 kwh more per year, plus their array performance drop around 5-6% already.
The problem is they just need 1KW or 2KW max (Thanks for TOU). It is extremely hard to find some installers agree to do such a small system. They have to go to 3-4KW system even not needed. The cost to change the existing string inverter and add into existing system is very high and not cost effectiveness.

As for the warranty, it will be installer specific, and in most cases, not likely to be worth much anyway.

At least, you have someone to be liability on providing labor for at least 10 years Estimate you will have at least 1 panel down during that 10 years. So, it might or might not be worth it. It depends .

One more item I like to bring up here. For normal household, it is easy to work with 240V AC as we use it daily. It is extremely dangerous to work with 600V-1000V DC. So, to add couple more inverters into the existing string of 240V is much comfortable than to add couple new panels into the existing 600V to raise it to 1000V. It will requires inverter replacement also.

[solar_newbie]

In my experience, home automation increases energy consumption. With LEDs I have many lights come on automatically at sunset. I have all kinds of microprocessors and networking always running. (Wifi, zigbee, z-wave, airplay devices)

But I agree with the principal of sizing correctly for today.

Noone can foresee the future . Everyone need to adjust in the future. Either cut back usages, add more resources or stay in the past.