Number crunching

Reminds me of one of my very first enjoyable Prius experiences.

 

So did you have to pay for this yourself?

 

Wow, so you started the project without knowing what the final cost is going to be? You are so brave.

I hope it won't end up like the Big Dig project. Good luck and keep us posted.

 

That was one of the nice features of the inspectors and utility here: not waiting, just turn it on, starting producing, then call them for final approvals.

The utility interconnection agreement was filed and approved before installation, while I was waiting for equipment delivery. Once I thought the installation was ready for a hot test, I pushed in the plugs, flipped the breakers, and voila! It was producing! Went inside and called the electrical inspectors, it was already afterhours so left voicemail, it was too late to get on their next day's inspection schedule, so they came the day after that. One minor deficiency, fixable without turning anything off, so conditional approval to keep operating. Fixed that, then called the separate utility's inspector. He finally gets to me two weeks later. He turns the system off (the first turnoff since my hot test began), pulls my temporary energy meter, does his own brief inspection, plugs in the utility's official production meter, clips on the seals, and turns the breakers back on. I lost probably less than ten minutes of production. It wasn't turned of again until needing to make hardware changes during my Phase 2 expansion five months later.

The utility's first-year energy production report, filled out and submitted by the customer in order to claim production incentives, clearly revealed that they expected pre-inspection energy production. There was a separate line to report how much energy was produced before their meter was installed, and how it was estimated. That was the only such report I filed, their meter readings covered all subsequent years.

This was from a very solar-friendly public utility. I've heard very different from other regions with less friendly utilities.

 

Talking about the tax credit, I needed to get a "this tax year" tax credit to cover my tax liability. For the four tax returns in the last 6 years, I used EV credit, but this year, I did not purchase a car for change. LOL

That left me to do some hard math to come up with a tax credit. Fortunately (or unfortunately), the unforeseen huge out-of-pocket dental bill is going to be deducted from the taxable amount this year. I was going to order a modular home battery system to take advantage of the 30% credit but I think I am going to save that credit for next tax year. My plan is to first buy a battery system. Then buy a DIY off-grid solar panel kit to tie to the battery storage.

I checked with another local but very new solar company a few months ago and asked if they could get the system installed by the end of this year. It was an 8kW system for ~$16K (before tax credit) cheaper than any other quotes I have received. The problem was that until they applied to the utility and got approval for the interconnect, they didn't know when the project would start or finish. The application can take up to 2-3 months. Historically, around where I live, the utility has not been very agreeable to solar micro-generator interconnecting citing the aging grid. I know of a neighbor (though the house is a few miles away) who was turned down by the utility to install the solar system. I did not want to pay the contractor an upfront 50% not knowing whether the project would be approved or not. The contractor said if not approved, the payment would be refunded minus ~$300 for the application fee.

I proposed to him that I would pay a $300 cash non-refundable application fee, and he can apply and see if it gets approved, then I will pay the initial payment at the start of the installation. He never got back to me. I guess, he was just looking for easy upfront money.

 

I also want to add battery storage, and prefer to do it in a way that can use my existing panels. (If The Big One takes down services during our typical winter dark overcast, I'll want to use all the panels to get enough energy to keep the lights on.) My older grid-tie microinverters were not initially programmed for islanded grid-forming use, but can take a firmware upgrade that works with Powerwall and Enphase battery controllers to do this.

The costs are not just the expensive batteries and controller, but also the rewiring to reconfigure my electric service entrance and main panel to a workable electrical architecture. My entrance now has no open spare space to insert the desired topology, so rework will be expensive. Maybe I should consider the next system expansion to be on a transfer switch, so it can be switched to run in isolation as a backup system, using just the newly added panels?

But since I'm at net-zero already, and can't sell surplus energy to the utility (this state's residential net-metering program gives the annual surplus to the utility for free), there won't be another expansion until we acquire a plug-in vehicle(s).

Hmmm. My system is wired as two halves. It wouldn't be hard to shift one half, across to the other side of a transfer switch and add battery and controller to that half only. A different and less desirable / functional topology, and would have to run extension cords to all powered appliances being run on backup power during the grid outage. Include a socket to plug in a traditional generator. But this could cover essential needs during the very extended outages that our local [ hard-core conspiracy survivalists | official government preparedness and resilience agencies ] tell us to expect ...

 

Well, I've been waiting for months for the bi-directional meter to come in. Supposedly, the township has had them on order for some time. they finally told me I could just turn the system on. They just can't account for energy being put into the grid until the new meter finally gets installed.

 

Since I won't get credit for what I generate while away during the day, I'm picking up a heavy duty timer to run one of my back up heaters while the sun is up.

 

Dang, it is unfortunate that this had to wait until after high solar production season ended.

I thought that standard traditional KWH meters were already bidirectional, though display only the net flow, not separate gross figures for each direction. When my system started producing, the utility still had me on an old mechanical meter. I put up own refurbished mechanical meter (borrowed from its normal function of measuring heat pump water heater consumption) in the socket that measures solar production. So the solar meter rolled forward only, while the house meter rolled forward at night and on dark days, then backward on bright days when solar production exceeded house load. Between those two figures, we could compute everything that anyone needed to know. (Time of use metering has not yet arrived here.)

The utility replaced my KWH meter with their own certified digital unit a couple weeks later, at the same time upgrading the house meter with a digital unit. The later still 'rolled' backward the same way the previous mechanical meter did.

Years later, the meters were changed to the automatic, self-reporting type. Now the house meter doesn't 'roll back', but instead records in-bound and out-bound totals separately, rather than showing a net figure. Unfortunately, it is programmed such that the outbound total is never displayed, but available only internally, and revealed only on the bimonthly billing statement. A long-promised 'benefit' of this technology, to be able to monitor our own usage in near-real-time on the utility's web portal, remains unimplemented.

 

My understanding is that electricity will still flow to the grid when production is in excess, but the current meter doesn't allow crediting of those kWhs to counter ones I use from the gird. Thus the plan to run an electric heater to bank some heat before the sun sets, and do laundry while the sun is up.

 

You guys are fortunate to live and receive electric where they allow customers to tie into the grid to sell or get credit for excess electricity produced. I think that is a wonderful opportunity to encourage home solar.

Unfortunately, in our area there is no need for that type of function for the meter as the Utility does not participate in buy back, credits or compensating for production that goes to the grid. Currently it is somewhat ambivalent if that is even allowed by the utility. Their website is not forthright on that question of allowing a home system to feed into the grid.