Residential Solar - Bits and Pieces
Hello readers! Let’s continue the conversation about residential solar. If you are just joining the series, it’s best if you start with “Residential Solar -The Issues”, the first piece in this three part series. Today I wanted to conclude our conversation by pulling together a few miscellaneous items we have not covered. Shall we begin?
First, I want to acknowledge an article by Steve Hanley of Steve’s Substack that was published in Clean Technica about the same time as I started this series. Steve is one of our Green Energy Evangelists, which means he wants to see an all-renewable world. In his story “Solar Plus Battery Storage — This Changes Everything”, Steve imagines killing the big utilities with stand-alone inverters. Steve, we disagree in many ways, and this is one, but I thought your voice should be heard in this Solar thread.
So, let’s take a minute and talk about solar plus batteries while we are on the subject. I truly believe with the shifting economics, that installing a residential solar system in this present time without solar storage batteries is a mistake. Any compensation for overgeneration into the utility is disappearing quickly, so you need to put that energy into a battery and use it later. I believe that systems without battery storage will quickly become obsolete. Fortunately, solar batteries are an upgrade, not a complete system change, but it does mean your inverter needs an upgrade. However, like all things, there are issues we should touch on
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Battery placement. Unfortunately, these are still lithium-ion batteries and still have that spontaneous combustion issue.
Unlike wiring or solar panels that mostly just smolder, when a battery goes into thermal runaway it becomes a full-on fireball. So, you may want to either build or put them in an out-building not attached to your home. You know, something that won’t hurt too much if it burns down. If you are further South, you may be able to simply mount the batteries on a vertical rack isolated from your home. I know StorEn Technologies has a special-order residential vanadium flow battery that has no fire concerns, but it will be a while before they are competitive.
Using your home battery system as a backup for power failures is a great idea, and a solar battery system will work for 98% of the utility power outages that occur. But if that 2% happens during a winter storm or a hurricane you can find yourself in real trouble. So be smart and install a simple generator input receptacle, and breaker with an interlock so your bases are covered. You can leave the portable generator of your choice in the original box in the garage, so it’s there just in case. See “When You are Ready for that Generator V” for a little more information on installing a generator inlet plug. Putting a tap on your natural gas meter to fuel your (tri-fuel) portable puts you in a very good spot.
Both Ford and General Motors offer factory bi-directional chargers that let you add the battery in your EV to the battery pool on your solar battery system. These systems get more readily available each passing month. While charging your EV battery with solar makes perfect sense, here are some words of caution tapping your EV for backup power. You want to stage it, so the inverter depletes the stationary batteries first before discharging your transportation. You also need to set a limit on how low the system will drain you EV battery before shutting down. If you don’t you may find yourself in the dark, with a dead EV and no way to escape.
Solar plus battery systems are very popular with middleman companies offering demand response services to utilities. When the utility calls the company providing the service, they send a command to your battery inverter which runs it up to full load pumping energy back to the utility for as long as the utility calls on them. This can deplete a day of charging within just 2-3 hours. The service company of course has a contract with you to use your system, but compensation can get pretty sparse. It’s up to you if you want to contract your system into a demand response pool, but make sure you get reasonable compensation. A couple of big players in the space are Sunrun and Generac Grid Services, but there are
lots of others. ($)
( I apparently got that part wrong, see comment by Jeffery Quackenbush below) Speaking about inverters, there are two types. There is a large single inverter mounted on the side of your house, and mini-inverters mounted on the solar panels. The mini-inverters tend to be a part on the solar panel, so if they fail and they are obsolete, chances are you are replacing the whole solar panel. The big central inverters are more independent, and if one dies that is obsolete, you can probably just do a little wiring to retrofit a new one. I would NOT do a solar plus battery system with mini-inverters, if they even exist.
In my first piece I talked about net metering, and how it was unfair to everyone else on the power system. Let’s dig into that.
The cost of the distribution lines that deliver the power to your home are fixed. It costs the utility the same money to maintain and improve them whether you use 1kwh a month or 2000kwh a month. The way utility rates are set up, we pay distribution delivery charges on a kwh basis. The utility must collect enough money to pay for the maintenance and improvements to the distribution system, or the utility will go bankrupt. If solar customers only pay the $15 account maintenance charge to be connected to the system, but do not use any energy, they are using the distribution system for free. Yes, I know they do not move any energy, but without that connection, their solar system would not work. So, the utility must increase the per kwh distribution delivery fees for everyone else to fund the distribution system. Not exactly fair.
Now let’s talk about my Gas bill. Columbia Gas of Ohio charges me a flat rate to deliver gas to my home over their gas distribution system. It does not matter if I use 1 therm or 500 therms, the price for delivery is the same, $51.33 for August plus tax. That is an extremely fair deal.
Both the electric utility and the gas company charge me per unit of energy for transmission. This works because Transmission systems, gas or electric, are like toll roads and you need to pay to use them.
In approximately 2016, Redding Electric Utility tried to go to a flat rate distribution charge. The solar industry rolled out their big national guns into a small City of about 100,000. Redding is also one of the conspiracy theory capitals of the USA. The solar industry went to the City Council and told them if they proceeded, they would flood the market next election cycle with negative information and none of them would ever hold an office again. Thus, ended that effort.
An electric distribution flat rate charge would make your electric charges fairer for everyone. Some would pay more; some would pay less. Solar owners connected to the distribution system would pay their fair share of the costs. It would also make it more difficult for random expensive rate increases because they would stick out like a sore thumb. But it would be an uphill battle to make the change.
Like any active system, your solar system benefits from regular maintenance and inspection. You may want to consider an annual maintenance agreement with a reputable company, just like you do, or should do with your HVAC system. With regular inspections you can get ahead of small problems, before the turn into big ones.
If you are installing on your roof, as one of our commentors recommended, it is a good idea to consider getting a new roof before you install the system. The solar system has to be completely removed to reroof, and any time you disturb an existing system you are asking for trouble. With a new roof, there is a good chance your roof will last the lifetime of the system.
Something additional to consider if you are reroofing for solar. Thanks to California wildfires there are now fire resistant and four-hour fireproof roofing materials on the market. This varies from non-wood product to fire treated wood sheeting, to fire resistant composition shingles. In addition to fire resistance, these are often better-quality products. So, if you want some security in case you have a solar panel fire, fire proof your new roof. Sorry East Coast, that will be a special order.
If you don’t like the look of solar panels, or your HOA frowns on them, you might want to consider a new roof with solar shingles. There are a half dozen manufacturers in this space including Tesla. Personally, I am a fan of the GAF Energy nail on solar shingle. This shingle is intended to directly replace your comp shingle and it is designed to work with their comp products.
CertainTeed also has a solar shingle (over comp) so both major composition shingle manufacturers are in the market. However, keep these things in mind:
Solar shingles are premium priced so expect to pay a fair amount more than a traditional solar panel.
Because the solar shingle is in contact with the roof it runs warmer, so it has a lower energy density. You will need to cover more of your roof with solar shingles to get the same output.
Solar shingles can fail like any other solar panel; with these systems consideration of a fire rated roof sheeting would be strongly recommended since they are in direct contact with the roof.
One final thing to touch on, it’s brand new and I do not know if it will go anywhere. A LinkedIn post mentioned portable solar panels backfeeding 120 volt outlets, no contracts. I took a look, found one on Amazon and one on eBay. Looks like they are less than a 1000 watts, so less than a portable heater. You would have to put them on a sun facing porch to get any value out of them. I have no opinion, it’s just too new.
That covers what I had in mind for residential solar, it’s a complicated subject. But if utility rates continue to increase as they have been these last few months, many families will be looking for alternatives. Taking a hard stand and telling people to just “suck it up” isn’t realistic with ever tighter budgets. If you are one of those looking for relief, make sure you do your homework, it’s easy to get burned. Review the comments as well, we have some very knowledgeable readers that added their advice. I hope you have enjoyed the series, and as always, I love to hear from you in the comments
Of course, under Net Zero, there is no fossil-fueled generator and no natural gas or propane service. Then it gets really exciting.
Interesting info. Practical experience with residential solar is very useful, especially as high utility bills give a new motivation to homeowners that replaces the motivation from disappearing tax credits.
Just a minor thing: There are some places toward the end where you might want to correct some (distracting) comma run-on sentences with periods.