One of my clients is a homeowner's association that is served by a 28-year old PV system that is approaching end of life. Output is down to about 40% of new, the custom analog inverter (750 VDC to 600VAC, 3 ph) has not been supported by the manufacturer for about a dozen years. Insurance on the old equipment is no longer available. The utility that originally installed the distribution to 24 homes, then turned it over to the homeowners, estimates that it will cost about $10,000 per home to upgrade the distribution to present standards and take over serving the homes.
I mention this because there was no end of life plan for this community power system. Only 3 original homeowners remain. No clear path to follow when the inverter finally fails. This is a solar financial horror story waiting to happen.
While not a 'barrier' as such, a major consideration in setting up a community renewable energy system is planning for its operation and future end of life.
There is a community PV system in Phoenix, Arizona that serves 24 homes and has operated for about 28 years. There is no sinking fund to pay for any major items such as failure of the inverter that is no longer supported by the manufacturer or to replace the deteriorating PV modules. The system was installed by a major PV manufacturer, local property developer, and local utility and turned over to the homeowners association to operate and maintain. Even billing for the energy according to legal requirements is a fuss.
It is not known what will happen if the inverter fails and cannot be repaired. Aside from the basic cost of the inverter (150kW), there is the problem of a replacement needing to meet current codes when the output in this case is 600 VAC and the array is bi-polar but asymmetrical (13 series 7-volt modules on the positive, 12 series on the negative).
The wisdom at the time of turnover was to legally restrict the land so that the homeowners could not sell the system and distribute the proceeds. If the system become non-functional it will be a fuss to just recycle the parts and return to normal utility use.
Meanwhile, the homeowners are not customers of the utility and cannot take advantage of other utility programs such as rebates on domestic hot water systems.
The lesson is to plan on the eventual end of life of the renewable energy system as well as possible at the start, to avoid future problems.
This article should have had some critical editing! But it was written by an editor.
"56 gigawatts (GW) of "long-duration" bulk energy storage" mixes energy and power terms. Power x time = Energy.
Hard to sort out the truly good info from all the fluff.
This article does not mention that a primary goal of the standards for flat plate PV modules is safety. The NASA Jet Propulsion Laboratory (JPL) addressed performance, reliability, and safety. There were problems in all three areas at the time (1970s). JPL purchased PV modules and systems for demonstration/development purposes on a $/watt basis and quickly determined that several companies rated their PV modules for more power than one would measure in the field. There were major problems with hot spots and high failure rates. JPL studied the problems, developed methods of testing to identify specific failure modes, and worked these into a set of purchase requirements that became the basis of later standards. There was substantial coordination of efforts by industry, academic, and users in the process.
There are continuing safety, performance and reliability questions to be answered. What should be the end of life criteria for installed systems when considering safety and performance? Climate has a lot to do with this, failure modes and degradation are different in hot/dry vs. hot/moist climates. Installation practices do affect operating temperatures and this can lead to differing degradation rates in the same installation. There is evidence that the accepted practices for PV module grounding may fail long before the basic PV lamination of the cells fails in moist climates.
There is a 27-year old shared, homeowner owned PV system in Phoenix AZ. It is still operating, but there have been problems over the years and there will be more problems.
The system was about 190kW with a 150kW inverter. I say was, because the output these days is about 60-70 kW, the PV array has deteriorated over the years. The inverter is still operating, but has been down for repair many times, for periods of up to 8 months. The manufacturer can no longer support such old equipment.
The design of the array is totally different from what has become the standard. The basic PV module is 5.8 volts at 8.6 amps and these are assembled with 10 in parallel and four in series into a panel. 100 such panels are used. Modules are glued into the frame and connections welded, making replacement of failed modules difficult, but none are presently available. Modules have deteriorated, been broken, and interconnects have failed. It is long past any warranty.
Over the years there have been billing problems, the homeowners purchase power and sell excess at commercial rates to the local utility. Net metering is not available, so excess is sold at wholesale rates while power is purchased at regular rates. Homeowners are responsible for the distribution to 24 lots and the underground cables are also deteriorated. Since homeowners are not direct utility customers, they can not take part in new solar incentives, a sore point with some.
The overall situation was planned by the builder and turned over to the homeowners with deed restrictions that make it difficult to shut down and sell off the land, etc. Soon that situation will have to be addressed.
The utility policy is that the system is grandfathered as to codes, but if changed in any major way all of it will have to meet present code to remain utility connected. A failed inverter or the large transformer will spell the end.
The final situation should be thought out up front.
As PV module prices decline to in some cases a dealer cost of $1.25/watt or less, and mounting costs increase because metals costs are increasing, the trade-off of tracking vs. fixed mount changes in favor of the fixed mount.
The statement "In all other states in the country, you do not need to be an electrician to handle and wire DC wiring, only AC wiring after the inverter." Is simply not true. Most states make no differentiation between AC and DC wiring.
Nor should they, in the predominant grid-tied systems the DC voltages can be up to 600 volts and are far more dangerous. Training or experience with these systems if important to maintain safety in the installation and operation of these systems.