Should Solar PV owner be able to profit off selling excess power?

[dhrivnak]

Well said. For me the grid is quite reliable. At $7.21/month it would take a VERY long time to pay off the generator. There has been one 22 hour period in 15 years when the grid was down. And i have access to a 2 MW "battery" with the "grid". I would have to fill half of the garage with batteries. No thanks.

 

[wycolo]

Thoughts:

1. St Lawrence is King - 348 units average flow vs 265 for Columbia River.

2. 'What if your Inverter breaks?' - Radian Inverters are 4kw each and scalable so use as many as you need, usually a minimum of 2.

3. 'Only 48 volts' (someone said). 48v is a *big* improvement over 12v which requires HUGE cables. Going to 96v would introduce much more of a shock hazard.

4. Wk057 has configured his salvage MS battery to run at 48v. The rest of us not so lucky to have such a huge bu battery can use ICE genset to reduce the size requirements of battery bank. Ideally the genset running on nat gas [city piping] or propane adapted carburetor. These dry fuels are very kind to ICEs and save you from having to deal with dangerous gasoline storage. Can tie genset into propane tank that runs kitchen stove, for example. Those that can reduce their nighttime electric usage significantly should be able to get by using the smallest battery bank possible. [research needed].

5. My setup will retain existing grid tie and min monthly payments to pay fair share to maintain grid infrastructure, among other reasons. I plan on switches to run as much as possible off the solar panels. BUT the solar setup will not be grid-tied since use of the logic plate will require that the main breaker be OFF before solar/genset can feed into the main panel. A 'dual either/or' system? Is there a name for this?
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[miimura]

I had a house built 2 years ago and had it pre-wired for a backup generator at the time. I never got around to installing the generator because it required a separate permit and the budget was tight at the end of construction. Part of the pre-wiring included installing an APC UTS10BI Transfer switch. This wall-mounted box is basically 10 individual three way switches that are microprocessor controlled. It is intended to be mounted next to your electrical panel since it is wired between the hot load wire and the circuit breaker for each circuit. The three way switching allows each circuit to be connected to either a UPS (plugged into the front panel with NEMA 5-15), a generator, or the utility. The control panel allows you to configure the size of the UPS and the generator so that it can do smart load shedding to avoid overloading either of those sources. Minimum run times and frequencies can also be configured on a per-circuit basis so that refrigerators and the like can be maintained properly. Any circuit that is set to draw from the utility will automatically switch to the generator when the utility is down and the generator is up.

I bring this up here because I think it would be relatively straight forward to connect an off-grid battery and inverter to the generator input of that switch. This would avoid any chance of back-feeding the grid by design. With a variable current, controllable battery charger you could set it to absorb any surplus energy from your grid-tied solar system, preventing feed-in at less beneficial rates and using battery energy to power through peak rates.

For me, right now, this does not make financial sense because of the favorable TOU net metering available to me. If that goes away, I will put a lot more thought into developing this solution.