Solar power options for a home

brekke - April 27, 2022

I’ve started looking into a solar system for home and I’m getting a bit confused/overwhelmed with trying to understand how it all works and if it is even worth it. Hoping someone in the forum can help shed some light on the topic for me. 

I’m in Oregon. We have a lot of cloudy days, but also a lot of sunny days. We have occasional short-term power outages, but the longest for us has been 12-hours. From a preparedness aspect, our most likely need for solar would be to mitigate energy costs as prices rise or for potential long-term need in the event of a Cascadia EQ event. We have a generator and fuel for short term 1-2 week needs. 

My confusion comes from how they work with the power company and batteries. One person that responded to a quote request said he doesn’t do battery set-ups because outages are so rare here. So, without a battery set-up, does that just mean the sole purpose of my panels would be to sell the power to the power company, thereby reducing our monthly costs (after the panel system is paid for)? Or would it provide power to my home during sunlight hours, even if the power company’s line goes down? 

It seems the overall expense, even with rebates and tax credits, would not be worth it without the battery backup option from a preparedness standpoint and that we would be better off investing in a generator switch to power essentials in the event of an emergency. 

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Brekke, the answers are so location and time dependent answer.  In Los Angeles, the rules differ between the various suppliers across the region and also seem to change yearly.  The laws are such that the power companies were required to pay for any energy you returned to the grid – called net metering.  Because of that, the solar panel installations were limited to 20% more capability than your average use over the last year.  However, LADWP sought and received a waiver for the payment for returned energy, and to instead provide usage credits that weren’t transferable. Because of that, there was no limit to the installed capability. 

They also have different rules for the use of batteries.  When we installed, LADWP would only permit any batteries to be utilized if the grid was down (a power outage) and there would be a large switch between the batteries and the house loads.  One other common use case would be to use them to offset our peak draw from the grid to low demand (and therefore low cost periods) like overnight.   Other companies did permit this.  I’ve not checked into batteries lately, but hear that the rules are a bit different now as the peak strain on the grid has moved from the afternoon when solar panels are illuminated to early evening when solar and wind renewable source contributions reduce. 

From a preparedness perspective, our solar system  doesn’t run anything in our home directly even when the grid is down.  As you say, it reduces your current energy bill and possibly is an income source once the system cost is recovered depending on your specific provider rules, local laws, energy use and solar installation generation capability.  For us, that break even point where it has paid off the installation investment was calculated to be 6 years and I think with the increase in electric energy costs it was even sooner.  I need to restart the research into batteries and the current rules for our system as well for preparedness. I know the batteries are going to be a lot more $$$ than a generator, but will not have fuel limitations.  I’ll run out of propane or gasoline rather quickly. 

I hope this helped you.  

 

Thank you! This does help a lot! 

 

I’ve heard that some solar setups which are connected to the grid, are turned off and are inaccessible during a power outage. The fear of leaving it turned on is that your solar panels would be backfeeding the wires and some poor electric company employee working on the lines would get shocked. Kind of pointless in my opinion to have a solar system that can’t even work in an emergency.

Definitely look into keeping your solar system off the grid and just powering your house. If only your kitchen is powered by the solar system and batteries, because it is too expensive to power the entire house, then that is better than not having it at all. 

 

Well, there is a point to solar even without storage–our panels paid themselves off a year or two ago and we now have free power for the next few decades, and free “gas” as well, since we have an electric vehicle too. Not a bad deal when gas where we live is over $6/gallon.

But you’re totally right–you need a battery in order to use solar while the grid is down, for the reasons you state. Generally batteries won’t pay for themselves over time, though in some locations they might eventually if they let you use stored solar in the evenings, when rates go up. In the not-to-distant you might be able to sell storage back to utilities when demand is high, and be paid both for the electricity and helping them have extra capacity. That’s not here yet though.

So the motivation for storage is usually preparedness, not savings. If you combine solar/storage with an efficient hybrid heat pump hot water heater, you’ll be the only one on the block taking hot showers too.

 

There are online calculators to tell you the payback time for a system in your area, the top result I got was solar-estimate.org.

There are basically two types of systems. The off-grid system with batteries and the grid tie. In a grid tie system there is no local battery, your panels first power whatever you have turned on and if there is any left over it goes to the grid. Any time your panels don’t cover your use you take what you need from the grid. But when the grid goes down so does the system.

There are a couple of reasons, first of course is that people working on the lines don’t want any possibility your panels are going to energise the lines. The electric code demands systems shut down when the grid does.

Secondly the panels and inverter have no way of modulating the output without a battery to buffer the current. A cloud passing over drops panel output a surprising amount and that drop would be translated right to whatever is trying to run off the inverter.

I’m putting together an off-grid system. I bought a large battery bank at a very low price. There are some great deals right now if you are able to get your hands “dirty.” First, hiring an installer will cost 2-3 times the price of the parts. Second, buying brand names like Victron, Outback, Sol-Ark will cost 3-4-5 times what you can get from other China vendors.

Here is a guy who is pretty knowledgeable. He started out building stuff very workbench DIY-y but has recently been recommending all-in-one systems. They still need some hands on but doable. He has affiliations and sells stuff too so caveats apply. I think this is his forum too, all forum caveats apply!

General caveat: DIY solar gets pretty involved, lots to learn! Lots of pitfalls. If you install panels on the roof there will be inspectors. Ditto grid-tie.
BUT, right now prices are as low as they have ever been. My batteries are half the price of anything comparable, my all-in inverter/controller is one third the price of the name brands. I bought solar panels @ <50¢/watt. Ditto LIFePo4 batteries.

I’m just some guy on the internet so all internet caveats apply! IMHO we are well into the transition period from fossil carbon to diffuse energy collection. As carbon gets increasingly unaffordable the demand for “renewables” is going to skyrocket. Could be they just keep getting cheaper and cheaper. Could be they reverse trend and become more and more expensive as demand comes up against supply.

 

Pops, Thanks for this more detailed set of information. I have friends with a grid tie and batteries that they can use to offset usage times and auto switchover in a grid down situation. So there are hybrid (or more sophisticated) options becoming available between the two basic setups you mention. Our friends used the same installers we did based on our referral, but had a different supplier and therefore different rules.  Seems like now is a good time to start checking into batteries once more.  How much physical space does your battery bank take?  That’s another issue for us – without basements or outbuildings, storage is a challenge.  

 

Alicia, I bought “server rack mount” batteries. The footprint of the rack is 24″ x 24″ and about 4 feet tall. I have 6-100Ah, 48v batteries so somewhere over 30KWh.

They look like this (this isn’t mine). this is 3 racks of 6 batteries side by side.

The system I have can charge the batteries from the grid, solar panels or even start a generator and charge from that. It can’t backfeed to the grid, but the tradeoff is it can be plugged into a 60a outlet, meaning it doesn’t require a permit or inspection and I can take it when I move.

 

Too big for our situation unfortunately.  I need all wall mounted like a tesla wall which is probably the most expensive per KWh, and also no longer available to purchase without a Tesla solar installation.  

 

On the problem of backfeeding the grid, all in one inverter/charger units contain an automatic transfer switch that decouples the panels/battery from the grid in the event the grid goes down. A manual switch that disconnects the panels, at the panel, is required if panels are on the roof as well, this is to protect firefighters.

 

Thank you for all of the thoughtful replies! Reading all of these is steering my decision towards holding off on a whole home solar solution for right now.

Honestly, our hope is to relocate to a location with acreage in the next 5 years (we already have family land offered to us, so it’s just a matter of getting a house built there), so I think it would be better to hold off until then before investing in a large off-grid system. That system would likely require a wind/solar combo due to the location. 

In the meantime, maybe I’ll just look into having a generator switch installed on the house. I’m told that is less than a thousand in our area. 

 

Whether it is worth it or not is a good question and pretty subjective. In my little brain the greatest threat to those in the first world is dependence on first world infrastructure. Chief among them is energy.

I became self-employed and stopped commuting many years ago. That made me less vulnerable to the whims of one person (or many) and reduced my commute to zero, we drive a tenth of the norm. I think we may also go completely off grid in another location sometime in the future. I bought the large battery in anticipation of that, and we have a huge uninterruptible power supply in the meantime. The capacity is 3+ days of the national average on-grid usage— of course much more in energy saving mode.

Frankly I worry about shortages of all the metals required to build these things making them unobtainable. Today that material all comes from China and Russia… great. Lithium is not rare necessarily, just nasty to process, but there are all sorts of materials involved, the cost of copper is 10x in higher than 2000!

Some folks buy battery vehicles to save gas, since we don’t drive much I just bought the battery! LOL

 

We’re similar in that neither of us have a commute. We actually sold our second car because it had sat for so long it was growing moss. Lol. 

I think you make a good point about potential materials shortages in the future, so that is something to consider. I think we’re going to back-burner it for now though while we contemplate our future location. 

It’s been my dream since childhood to live on a farm, so I think I’ll put my efforts into achieving that and hopefully be able to incorporate solar and wind into that plan. 

 

I’ve been working for an east coast solar company for almost two years. A pandemic re-direct of sorts. I started as an installer, but my experience and age got me out of the field rather quickly and into operations and now sales and design.

I would find a reputable installer in your area. We’re part of a co-op and would recommend any of the companies in this link. Just click on Oregon. https://www.amicussolar.com/our-member-owners/

Most every residential system is designed and installed as grid-tied because it helps offset your utility bill by sending electric back to the grid when you’re overproducing, the grid is your battery. When a system is grid tied and without battery storage, the solar goes through a rapid shut down so that it doesn’t backfeed the grid.

With battery storage there is additional hardware that prevents this and you’re able to keep solar running and charging the batteries in a power outage. Indefinitely if sized right and your loads are manageable. Look up cases in Texas deep freeze and just recently in Puerto Rico.

There are plenty of off grid and diy battery systems, but the big names like Tesla Powerwall, Generac, and Enphase all have batteries that work with grid tied systems and continue to operate in a power outage.

Enphase has a new and somewhat untested technology called Sunlight Backup. It’s all the extra hardware that goes with a battery without the battery. It allows the solar panels to function and feed the house when the grid is down but the sun is up. No other system has this. But know that it’s only a few circuits with a low maximum amperage. And if a cloud comes out, everything might shut off.

If a battery depletes fully overnight and the grid is down, enphase is the only system that can black start in the morning. The others will have to wait until the grid is back.

Also, good luck getting a Powerwall. They are so backordered we don’t even sell them anymore and we have very unhappy customers that order them at the end of 2020 and still don’t have them.

The tax credit for solar is still a decent 26%, set for 22% next year and 0 after that. I like to tell people that they’re locking in your utility rates now for the next 25 to 30 years. If you could do that with gas or food you surely would. And as long as battery storage is solar powered it’s also got the same tax credit.

Here’s a website that compiles all the incentives. https://www.dsireusa.org

 

Thank you, DaveH!  The Enphase system is intriguing.  the ability to black start is an incredibly good feature to consider in the trade study.  If I understand correctly, it’s a black start of the grid that is the real concern for power companies.  

 

Hey brekke, check out this new backup power system by Ecoflow. Incredibly simple to set up and will save a lot of frustration and also installation cost.