Frequently Asked Questions

Since NEXTEK Power Systems' technologies are relatively new, we often get asked the following questions:
Q:
 How do you keep the lights on at night?

A:
 From the Grid!
Lighting at night would be a problem if our system was simply PV panels attached to DC lighting ballasts. It's important to remember, though, that we're 'Grid-Connected' as well. The NPS-1000 takes all the power from the lighting, then adds whatever else it needs from the grid. Grid power is converted to DC, added to the power from the panels, then sent to the lights.

Q:
 I don't want to rewire my building?

A:
 Very little rewiring, if any, is needed. Currently, your AC lighting circuit is probably wired from a 20Amp fuse in a lighting panel to a cluster of lights. By installing the NPS-1000 between the lighting panel and the cluster of lights we can avoid major rewiring.

Q:
 How do you justify changing all of the ballasts?

A:

The system works best in a new construction or lighting refit situation. In addition, there are often other advantages to changing your lighting fixtures. For example, if you currently have T-12 (1 inch) fluroescent tubes installed, switching to high efficieny T-8 tubes can save energy, qualify for state or local rebates, and provide the opportunity for the installation of DC ballasts.

It is also important to realize that many brands of universal ballasts have a DC rating, or can operate fine with DC. IN this case, we do not need to change the ballasts... although we may need to install a higher voltage system.


Q:
 Can the ballasts run on both AC and DC?

A:
 No. The ballasts run on DC only. It's the NPS-1000 that can run on AC or DC.

Q:
 Isn't DC more dangerous?

A:
 No. There is no evidence that DC power is more dangerous or lethal than AC power. The lower voltage DC (48V) used by this system is even easier to manage.

Q:
 How many roof penetrations do you need to install the system?

A:
 Ideally, power from each 48VDC, 1000 Watt array is run about 100' to the NPS-1000. If roof penetrations are acceptable then one penetration for each 1000 Watts reduces wiring losses. This is common where roof penetrating racks are used or BIPV (building integrated PV) is used. If roof penetrations are not acceptable, then a string combiner/de-combiner configuration can be used to consolidate the strings.


Q:
 Does the Nextek system work in a residential application?

A:
 Not usually. Because the Nextek system does not feed back into the grid, there must be a daytime DC load sufficient to use all the power generated. Lighting is an example of this load. Other DC loads can include DC motors, variable speed frequency drives, and computer systems.

Q:
 Do I need to replace light swiches with DC rated switches?

A:
 NO! Each ballast is equipped with a low-voltage control wire. To switch the lights, simply run low voltage 'telephone' wire from ballast to ballast, theh to the existing light switches. In addition, the small amount power present in the low voltage control wire is enough to power an occupancy sensor. This means that installing occupancy sensors requires no significant time or materials.



Q:
 What if the lights are not on all day, every day?

A:

Then this may not be an ideal job of the Nextek system. The basic concept is to use All the local power, where, when, and how it is generated. This assumes that the loads can use all the power. In almost all retail and office establishments, the lights are on during the day -- meaning that the lights can consume the power whenever the sun is out.

In some cases, where a business is closed on the weekend the value peoposition still works because power is generally less expensive on weekends.



Q:
 What if the PV system produces more power than the lighting system uses?

A:
 In this case, part of the PV system can be dedicaed to the lighting load while the remainder can be inverted to AC and directed to the AC power system, or fed back into the grid.



Q:
 Is the Nextek System more efficient than an inverter system?

A:
 YES. Depending on several factors, eliminating the inverter and installing high efficiency DC ballasts can cause the system efficiency to be improved by 20 to 50%.



Q:
 Do I need batteries to keep the lights on during a power failure?

A:
 No, not if the sun's out. Because the Nextek system does not need to shut down during a power failure (like an inverter does), sufficient sunlight will generate enough power to keep the lights on during a power failure. Batteries can be used to keep the lights on during a cloudy day or nighttime power failure.



Q:
 What approvals do the Nextek products have?

A:
 UL Listed
Listed on the California Energy Commission list of elligible inverters.



Q:
 Do these systems qualify for rebates?

A:
 Yes. We qualify for any state and local rebates available to an inverter-based system. Even though we do not feed back to the grid, we look, to the utility, the same as a PV system that is sized under the building load (which does not feed back either).


Q: Do some PV systems/modules pollute the environment because they are made with toxic substances such as arsenic?
 
A: There are many different types of PV module technologies.  98% of them do not use any toxic substances and can be recycled or disposed of in ordinary landfills. 

Q: Will Solar Panels be too heavy for the roof?

A: Most roofs can accommodate between 8 to 10 lbs/sq ft of additional 'dead load' weight, though specific roof load capacity needs to be assessed for each project. A PowerGuard tile typically weighs less than 6 lbs/sq ft, though heavier panels are required in some extremely windy applications.

Q: How do solar systems respond to cold weather conditions and snow load?
 
A: Systems are designed to operate from -40º C to 90º C, and have been proven reliable under very cold conditions with extensive snow buildup. If there is a light snow-fall on a bare system, the array will tend to be the first part of the roof that melts off because the cells retain some heat. If there is snow build up, then the snow will melt at the same rate across the whole roof since there won’t be any retained warmth in the solar array.
 
Q: What kind of maintenance does a PV system require?
 
A: A fixed PV system is solid state and has no moving parts, making it the single most reliable form of commercial electricity generation, with very little maintenance required. In areas where it does not rain for many months at a time, solar panels can accumulate dust and dirt. Washing systems a few times a year during the summer months is recommended in dry climates. Performance impacts from soiling are marginal, particularly in climates where it rains at least once a month.
 
Q: Does a tilt angle improve system performance?
 
A: Performance enhancement from tilting depends on latitude and climate of site. For most sites optimal performance is realized at latitude minus 10°. However, for most sites below 40° latitude, improvement from tilting is marginal, since the tilt improves winter energy at the expense of summer energy.
 
Q: Does the solar system offer significant environmental benefits?
 
A: Yes. Solar electric systems have an operating life of over 25 years, and spare the environment from thousands of tons of harmful emissions, by avoiding the production of electricity generated from traditional fossil-fuel burning power plants. These emissions include nitrogen oxides, sulfur dioxide and carbon dioxide, which are major contributors to smog, acid rain and global warming.
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 




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