Net metering - hybrid solar inverter system question

[coltonk]

TL;DR

solar inverter

Does anyone know of a manufacturer who makes larger inverters (15-20KW) that can use either an AC or DC generator to product power for net metering. Ive searched for days and all I come up with is systems that require solar panels to do the net metering. I'm not trying to power any loads, just want to do the net metering. I cant believe that there are no commercially available grid-tied inverters that simply take either AC or DC and send it back to the grid via net metering.

 

[Ken Fabian]

TL;DR Summary: solar inverter

Does anyone know of a manufacturer who makes larger inverters (15-20KW) that can use either an AC or DC generator to product power for net metering. Ive searched for days and all I come up with is systems that require solar panels to do the net metering. I'm not trying to power any loads, just want to do the net metering. I cant believe that there are no commercially available grid-tied inverters that simply take either AC or DC and send it back to the grid via net metering.

Not sure what you are after. Net metering is not strictly a product of the inverter type, it is how the system is wired to the meter and the type of meter - and crucially, what the rules about it are. Inverters and grid connections need to conform to appropriate local requirements.

Different places, different rules. Earliest grid tied solar around here (Australia) connected so that any feed-in to the grid sent old style disc meters backwards but such meters and net-metering are anachronisms and meters now count feed-in separately to power drawn from grid, each with separate pricing - which may change according to what time of day and how much feed-in, imposed daily or monthly limits etc.

If you still have an old style power meter upgrading it to the required type is a requirement to connect solar here. There are moves towards grid operator capability to remotely turn feed-in off and on according to grid management needs.

 

[coltonk]

I understand net metering, local power company requirements and NEC code related to net metering, but I need to know about the inverter, specifically whether any grid-tied inverter is offered by any manufacturer that can perform straight net metering from a generator to inverter to the power grid. Other than solar, I can not find any manufacturer that supports this. Grid tied inverter are made to perform the need tasks to tie into grid power including protecting the people working on the grid during a power outage. I am hoping someone on here can point me to a group of manufacturers that offer the equipment. Existing solar inverters are an option and I can probably make that work but I would much prefer an AC system that can take incoming AC power and preform the phase match along with any other power company requirements at a cost as inexpensive as solar inverters.

 

[Rive]

You can start by looking up manufacturers for biogas and micro-hydro system components.

 

[The Fez]

I don't think you are going to find what you are looking for. Even in large wind farms, where the turbines in the nacelles produce AC power, it is then converted to DC before being fed to in inverter to connect to the grid.

 

[Fisherman199]

i have had utility customers which use Combined Heat and Power (CHP) gas turbines to generator for their location and to sell onto the system via net-metering. the CHP modules have inverters and can operate as either following or separately derived system (using either utility voltage reference, or creating their own reference once utility voltage is lost). CHP plants can get rather large for distributed generation. Some several hundred kWs.

 

[Fisherman199]

I understand net metering, local power company requirements and NEC code related to net metering, but I need to know about the inverter, specifically whether any grid-tied inverter is offered by any manufacturer that can perform straight net metering from a generator to inverter to the power grid. Other than solar, I can not find any manufacturer that supports this. Grid tied inverter are made to perform the need tasks to tie into grid power including protecting the people working on the grid during a power outage. I am hoping someone on here can point me to a group of manufacturers that offer the equipment. Existing solar inverters are an option and I can probably make that work but I would much prefer an AC system that can take incoming AC power and preform the phase match along with any other power company requirements at a cost as inexpensive as solar inverters.

you will not find anything like you mention at comparable cost to solar inverters.

net-metering is done by the utility meter/meters. smart meters can be programmed to net meter using only one meter. traditionally two meters were used at different polarities.

most utilities will be most concerned with the isolation point (2-3 pole load breaking manually operated switch behind a locked cabinet) and that your system will not operate as forming (separately derived).

 

[oz93666]

i have had utility customers which use Combined Heat and Power (CHP) gas turbines to generator for their location and to sell onto the system via net-metering

It's a puzzle to me why we don't see domestic CHP used everywhere ... An IC engine driven by house gas producing electricity which is sold to the grid and will easily cover the cost of the gas , all the waste heat warms the house for free ... The noise is the only problem issue.

 

[Rive]

It's a puzzle to me why we don't see domestic CHP used everywhere ... An IC engine driven by house gas producing

With a heat pump (and a clutch) it could be even more flexible. Especially if the generator could act as a motor too. And with a heat tank, of course. For a floor heating, why not?

There are just two issues.

One is, that (in the EU, at least) domestic gas usage is not really preferred and actively phased out. Especially in cities.
There are both reasons and excuses for this, but the fact remains.

Other is, the good old insulation paradox. Once you have good insulation - and that's a basic requirement these days - less spending would be needed on heating, so with more complicated machinery that 'less' will grant you only diminishing or no return at all for your investment.

 

[russ_watters]

It's a puzzle to me why we don't see domestic CHP used everywhere ... An IC engine driven by house gas producing electricity which is sold to the grid and will easily cover the cost of the gas , all the waste heat warms the house for free ... The noise is the only problem issue.

They are expensive to operate (they need 24/7 staffing) so they are only financially viable if they serve very large buildings or campuses. And they require a continuous load for the heat*. A couple of my big pharma campus clients have them, but a large apartment building from the '80s decided it wasn't worth the trouble.

*Pharma has continuous load for heat, even in summer.