We are working on a templated approach for connecting a set of thermoelectric generators to a power main within an industrial facility. The generators natively produce DC current. We are thinking of something like: [ generators ] --> [ DC combiner box ] --> [ grid tie inverter ] --> [power main] {power load}. Our parameters are safety, losses, and (of course) cost. Can anyone offer tips on a repeatable approach to solving this class of problem?

The question is a bit unclear. Are you looking for removable connection which is actually a plug-in connection (plug / unplug). Male - female connectors? On solar PV systems there s lot of connectors of this kind, if you are asking for connectors.

I apologize that the original statement is unclear. The context is permanent installation of skid mounted power generators (waste heat to energy).

We are hoping to create a (close to) "self service" process where Customers can determine feasibility of generator installation. Conceptually, this would be like going to the Dell computer website and configuring a computer. In this case, it might be 1) select your facility load type, 2) select your GTI, 3) select your generators, ... The final output would be a schematic and estimated price.

Replace "Customers" with "Licensed Professional Engineer" to get started. Any time you add local generation it is not as easy a selecting the generator size. You must consider fault currents, Local Utility restrictions, Grounding, transient conditions, Protection schemes, etc. Build a relationship with engineering firms first. Those partnerships will help make successful installations.

Hi Cris. Thank you for your comment. I think that the term "schematic" in my comment may be misleading. I intend the word as "abstract system representation" rather than "complete physical build instructions." I am trying to answer the logical Customer question of "roughly what will the generator system cost?"

Gaining a reasonably accurate answer will require that the Customer provide some data. I am thinking that AC/DC, AC phases, specified system voltage, peak load (W), and historical average load (W) would characterize the baseline. What facility parameters would a Licensed Professional Engineer expect to initially scope a generator system?

First let me preface to say I like the concept. I would like to see more detailed information on how the system works.

My concern with local generation sources of any kind is how they affect the balance of the facility wiring. If adding a local generation source causes the available fault current to a level above the ratings of the breaker panels, your "Rough cost of generation" figure may be off by a large order of magnitude. We see often times while conducing Arc Flash Hazard studies breaker and panels that were not properly sized especially after expansion projects.

Many local utilities will require specific protection schemes when a customer adds local generation. They may also require a special meter to be installed that will add power quality monitoring or net metering capabilities. All these items may have a cost factor that would need to go into the project cost.

If I am asked to do a generator installation project the first information I need to know from the client are the following information:

1. Your existing system power one-line diagram showing your power supply infeed (commercial power) and your system distribution of loads.
2. I need to know the loads that you like to be powered by the generator
3. Generator supply has several categories (by electrical code requirements). What function / purpose do you intend to use the generator for?
a. Emergency generator
b. Standby generator
c. Legally standby generator
d. or a co-generation for parallel operation with your grid supplied power (commercial power)

@Custo - We are doing co-generation with the intent of reducing grid consumption (utility power bill). The generators are not considered dedicated to a specific load nor standby.

@Cris - You bring up an interesting point on the many design and installation checkpoints. Where does the power generation responsibility end? It would probably not be logical to ask a power generation project to bear the cost of bringing deficient existing wiring up to code (although it may make sense to do both at the same time). Where would a company logically draw the line on "the generator system" v. the "rest of the system?"

I think Partrick should give more explanation about "thermoelectric generator" because everybody here thinks that it is a power generator of multi-kilowatts size.

The thermoelectric generator to my knowledge produces electricity base on heated thermocouple wires and each generator may produce a few hundred watts (not kW) of DC (24V?) power only. There the "power mains" to my understanding is only a small capacity power source.

@Partrick - Will the cost per KWH of your generator production be very competitive with the cost per KWH of your grid power? or will your life cycle cost provide a feasible project investment? I believe there should be a feasibility study before the start of the design.
In places where the cost of utility electric power is exceptionally high such as small islands with high density of population, feasibility of the project is viable. Large scale solar pv power is one viable project if the cost of the PV panels becomes very competetive.

If the addition of local generation adds to the available fault current to a point where the existing panels are now over-dutied, it should be the responsibility of generation project to fund the cost of upgrades. That would be a cost that only exists if the generation is added.

Also, if adding generation adds a requirement from the local utility to add additional protection such as reverse power plow relays, that is a cost that should be project based.