Downside of Leasing Solar Power / Battery Bank Discussions

David Trammel's picture

I've been to a few sustainable living lectures that had people from companies who lease you residential solar systems. Being a renter I haven't looked very closely at the contracts. Here's an article about the downsides

What Happened When I Bought a House With Solar Panels

Two days after walking through Jug’s ham shack, we made an offer. A week later, just before we entered escrow, we learned the solar array hadn’t belonged to Jug. It was, in the language of the industry, a third-party-owner, or TPO, system, belonging to Sunrun Inc., the largest provider of residential solar in the U.S. I started looking into the TPO model. It’s used less often than it once was, but it’s been important in making residential solar, once out of reach for most people, much more widespread. The reason is simple: Homeowners usually pay nothing upfront. A company like Sunrun puts solar panels on your roof, connects them to your home, and claims a tax benefit for owning the system. Going forward, you pay Sunrun to provide the bulk of your electricity needs instead of your utility.

I’d soon learn that the system was tied to the title of the house. It appeared that if we bought Jug’s place, we’d have to assume his lease arrangement with Sunrun. I wasn’t sure how I felt about this as a buyer, but it definitely piqued my curiosity as a journalist. I set out to examine the value proposition carefully.


ADMIN NOTE: I've changed the name of the thread to reflect the side conversation on Battery banks that we got into.

Let me say before I forget, the italics are really a bitch to read on my screen. The regular font is hard on the eyes, too, but (almost) doable. They both look purplish on my laptop screen, and I have futzed with my screen controls, but can't find a setting that helps much.

That out of the way, the costs in the article sound way out of line. Prices for solar panels have dropped 70% in the last decade, and tax credits have also dropped. Here in Central Illinois we have had a number of churches install solar, I've been to several meetings on the subject. It seems like a number of solar installers have their own financial branch, bringing investors and consumers together. The consumer leases the solar system for about seven years, and venture capital investor underwrites the cost of the installation and takes the investment credits during that time.. At that the end of that period, the consumer can purchase the system outright. Don't know how that works if the consumer dies during that time. That's what the fine print on the contract is about.

The details will probably vary by state. Links for Illinois:

David Trammel's picture

What browser are you on? Chrome allows me to magnify a page in the settings. With my eyesight most pages are set at 125%. Software updates are in the works, including the change of color but I expect it to be at least a month away, sorry.

As for solar costs, I haven't looked at them. The purpose of posting the article was to make people away of that "fine print". Personally I wouldn't have a leased system, nor one that was grid tied. My sister's backyard gets enough sun to grown a garden but not enough to generate any real electricity.

As for the drop in the price of solar equipment, much of that decrease has been from cheap Chinese imports and I have not heard good things about their life nor reliability. That the lease time has dropped to seven years makes me wonder on the life expectancy on the panels. I believe a couple of regulars here have experience in solar, perhaps they can chime in on the ir experiences.

Blueberry's picture

Press and hold the ctrl key and keep pressing the + key. David in your part of the world 3 hours of sun light a day is about all you are going to get. If you had 10 - 100 watt panels you will feed 3Kw into the batteries you will get about 80% of that out of the batteries. You inverter will at best give you 90% out of what goes in. I am sure Sweet tator man can give you some good info as he is a EE. IMHO solar will give you a few lights and some cold beer.

Sweet Tatorman's picture

"...and some cold beer." Sounds like reason enough for a system to me!

I use Firefox. Because my laptop is small, I usually set the zoom at 80 or 90%. I just expiremented: if I crank magnify up to 133% it doesn't look like elvish anymore. Doesn't even look italic for that matter. Personally I do most everything in New Courier if I can.

I realized you were talking about leasing and not buying, but it sounds to me like the lease is out of line with today's market prices. The leasing company may be looking for suckers. A prospective buyer "who really loves the place, but..." might go to the leasing company with information in hand and work out a short-term lease-to-own arrangement.

Sophie, The problem with fonts sounds like the sub-pixel text rendering setting is wrong.
What OS are you using? Windows calls this "ClearType" and other OSes call it sub-pixel antialiasing or sub-pixel rendering or font smoothing or similar. Wikipedia will explain to you what it actually means, but if the orientation of the RGB parts of your screen pixels are different than what the OS is trying to smooth with, then you get weird colour fringing on letters.

David Trammel's picture

The back roof of the house's room addition is just about the only place I could put panels, and then there is still a good size tree to the South. I could put a few panels on the 400 sq ft Workshop/shed I have planned for the backyard but there again, I'm not sure the cost is worth the trouble.

I do think that a decent backup battery bank might be worth it.

Unless the US economy really collapses big time, and then I'm screwed because my only retirement income is Social Security, I suspect that what I will have to deal with are brown/black outs and occasional interruptions in electricity during Winter snowstorms and Summer heat waves. For Winter we have a Franklin stove in the room addition and I intend to maintain a good size wood reserve. During Summer, we have a basement and while its only 3/4 in ground, I hope it will provide some measure of cool space, if the power goes out. The duplex I have now, has a fully dug in basement, and I haven't had to turn on the air conditioning for the past three years, even during some very hot spells.

I did have a small fan blowing on me when I slept down there, so that's a power draw.

My biggest concern then is refrigeration and freezers. We'll likely have a large refrig upstairs in the kitchen and two 5 cbft freezers downstairs. A battery bank that can provide emergency electricity for them for 3-4 days would be ideal.

Not sure how big that is.

There is a small room under the front porch, accessible from the basement. It has an old fuel oil tank for the previous furnace. One of the things I'd like to do is have it removed but I have to be careful on the issue since any leakage may count as a EPA toxic spill and make me liable for expensive clean up.

It would make a nice little room for batteries though or a root cellar.

Sweet Tatorman's picture

I've done what you are thinking about though on a somewhat larger scale as I was considering a few more loads and a somewhat longer duration. I did a fair amount of testing and pencil pushing over the course of a year before purchasing the highest cost item in this type of system which is the battery at well over 50% of the total system cost. I have few conclusions that you may find of use.

Once you get beyond designing for a couple of days of supplied power you need to take a good look at the efficiencies of your existing or planned appliances. If your existing appliance is well away from the most efficient end of the available spectrum it may be less expensive to replace it with a more efficient unit than to buy the incremental battery capacity to use the less efficient one.

An example from my own situation. My old refrigerator would have required 2 kWhr in the Summer or 1 kWhr in the Winter per day to operate if the utility power were out. The lower value in the Winter is due to the lack of any alternate heating so interior dwelling temperatures will be significantly lower lacking power.

Compared to added battery expense it was a "no brainer" to buy a more efficient refrigerator of the same volume which halved the energy requirement to 1 kWhr/day, Summer, and 0.5kWhr/day, Winter. My existing freezer is a 10 ft^3 chest type and an efficient model. It lives outside on a covered porch so is subject to even greater swings in ambient temps than inside the dwelling. Based upon extensive testing I assumed 1 kWhr/day Summer and 0.5 kWhr/day Winter for the freezer in sizing my battery bank.

Based upon your described system, some very "low hanging fruit" would be to replace the two 5 ft^3 freezers with a single 10 ft^3 unit. All else being equal it would only require 26% more energy to run a 10 ft^3 unit than a *single* 5 ft^3 unit. Similarly, a 15 ft^3 unit only requires 46% more energy than a single 5 ft^3 unit. This is because the heat gain from ambient to the freezer interior is proportional to the surface area. Assuming that the HWD proportions are the same for the various sizes, the exterior surface area varies as the cube root of the volume. It is not uncommon for a manufacturer to use exactly the same compressor unit in their 5, 10, and 15 ft^3 models. What differs is the amount of time it runs.

If I assume that you have refrigerator and [single] freezer with efficiencies similar to mine it appears that you are looking at on the order 2 kWhr/day in the Summer which is the more demanding scenario. Since you are essentially keeping the battery in standby and cycling only rarely I would design to an assumed of 80% depth of discharge [DOD]. Allowing for the energy loss in the inverter and an 80% DOD target I would assume that you can deliver 70% of the full battery energy storage to the actual appliance before exceeding 80% DOD hence you would need a 100% DOD energy storage of 2/0.7=2.86 Kwhr/day. As Mr B noted you would need a lot of the type of battery he provided the link to.

There are some technical reasons for not having a bunch [a couple is OK and common] of parallel strings to add up to the capacity needed. More desirable is larger capacity individual cells or batteries limited by the weight you are willing to move around. For what you are looking at something in the "L16" form factor is right. These weigh in at around 120 lbs each. The "L16" is not a specific model but instead a generalized size and shape recognized by the industry just as "group 24" or "group 27" are standardized form factors for automotive batteries. The "L16" form factor is about the same footprint as a large automotive battery but about twice as tall at 16-18". Linked below is a typical datasheet for an "L16" intended for deep cycling application:

Note that these are 6V batteries so you would need to use them in multiples of two if you are planning a 12V system. Page 1 of the datasheet shows a full 100% DOD energy content of 2.50kWhr so a pair would get you almost 2 days under the assumption of 2 kWhr/day appliance usage or 2 pair for almost 4 days. Current pricing on these is ~$400 each with no core charge. If you wanted and could afford more capacity you should consider going to 6 individual 2V cells in series rather than 3 parallel pairs of 6V batteries. The link below is for 2V cells each with 2.5 kWhr 100% DOD capacity. BTW, my own system uses 12 of these for 30 kWhr at 100% DOD. Pricing is about same as the 6V ones.

My sense is that you will be put off of this idea by the costs I have cited just for the battery alone. There are a few ways to hack this problem at lesser expense if you wish to discuss further. Some of the hacks require being relatively handy both mechanically and electrically. Others do not.

Good news is that it sounds like you have a good place for your battery bank. Assuming that you are doing everything right with care and maintenance, ambient temperature has a big influence on standby life. Check out the note on the lower left of page 3 of either linked datasheet. Reducing ambient temperature by 10C potentially will double the expected life.

Blueberry's picture

To power a frig and 2- 5cuft freezers for 3 to 4 days is going to take a lot of these. You do not want to discharge deep cycle batteries more than 25% if you want to get any kind of service life. This is the battery I use, can get a replacements today. Have had good luck over the past 20 plus years.

David Trammel's picture

I was hoping you would chime in Tator, lol.

I fixed a bit of your formatting on your post so it is more easily read. Was it you who mentioned the cheaper quality of Chinese imported solar panels? I thought you had had some experience with them. Sophie mentioned that the cost had come down and the leasing time as well and I'm wondering if that relates to the lower life of Chinese imports.

Let me ask you this about battery life.

Would it extend the life of the batteries if instead of holding them at full charge for an emergency, that I set up them up to power the essential appliances in normal non-emergency times? That is have the refrig and freezer on separate circuit and powered off the battery bank, and when the bank got low in stored power, have the grid electric begin recharging them?

My only experience with rechargable batteries is for my two DeWalt 12v drill motors. I have perhaps 8-9 batteries, all but the last two purchased are dead and won't take charge. Most of the time they were kept on chargers until needed, and then returned. I've since read that not letting them decharge causes a memory to develop where the battery doesn't hold charge.

Considering that deep cycle batteries are expensive I want the longest life possible.


In a funny fact, my place of employment has a vertical storage system and side loading forklifts, that run of some huge batteries ($5000 each). The battery tech came down the other day to teach how to extend the life of a battery.

He mentioned that batteries operate best at 70 degrees. Cold and high heat especially makes it hard on them. He said the simple act of turning on your headlights on your car for a minute or two, would cause the battery plates to warm before you needed to start the car AND greatly extend the life of your car battery.

He said his current car battery was over 7 years old and still good.

Sweet Tatorman's picture

>Would it extend the life of the batteries if instead of holding them at full charge for an emergency, that I set up them up to power the essential appliances in normal non-emergency times? That is have the refrig and freezer on separate circuit and powered off the battery bank, and when the bank got low in stored power, have the grid electric begin recharging them?<

Very emphatic no!!! Keep them charged at all times. Use them only when needed.

>Considering that deep cycle batteries are expensive I want the longest life possible<

See the above.

>My only experience with rechargable batteries is for my two DeWalt 12v drill motors. I have perhaps 8-9 batteries, all but the last two purchased are dead and won't take charge. Most of the time they were kept on chargers until needed, and then returned. I've since read that not letting them decharge causes a memory to develop where the battery doesn't hold charge<

Optimum charging strategy depends on the type of battery chemistry. The memory thing mainly was a problem with NiCd batteries subjected to continual over charge on dumb chargers. NiCd has largely been phased out for environmental reasons [Cadnium].

While my first impulse is to say that your battery tech is full of sh*t, I will instead just recommend that he be ignored for your purposes. What he says about the forklift application does have some basis. Forklifts are a very high drain application and often the batteries are sized such that they would be mostly drained in a single work shift of operation prior to needing charging. This high of a discharge rate is hard on Lb-acid batteries at lower temperatures. There is also less obtainable capacity at low temperatures. See the Percent capacity vs temperature graph on page 2 of either of the datasheets I previously linked. More is available at temperatures greater than 70F. His arbitrary "operates best at 70" is just his balance between lower standby degradation at lower temperatures, higher available capacity at higher temperatures, and higher degradation at lower temperatures when subjected to heavy discharge. The headlights thing should be totally ignored. While higher battery temperature is useful, the degree of heating with a couple minutes of headlight use is negligible.

David Trammel's picture

Ok my maintenance man and I had a discussion at work about this and he explained the difference between battery shelf life and the number of expected recharges you can get out of one. While a battery may sit on a shelf charged for years, one that has to go through repeated discharging and recharging won't last as long.

Is that why you say not to use the batteries/electricity in an emergency set up like I'm thinking of?

There are batteries in a solar panel setup, which hold the day's earned electricity and feed it back into the home's system. Does the repeated cycles then decease the life expectancy from the batteries?

Blueberry's picture

If you look at the info on trojan batteries they give a app number of cycles the batteries will handle before DOA. The number of cycles is based on a 50% discharge if you take them down more than 50% the battery life goes to H@!! My first set of batteries was a set of trojan L16 they lasted only 18 months. They were taken below 50% about 10 times! Other types of batteries do not have the problem of shorter life by being fully discharged but the COST. So after 100 plus years of making batteries lead acid is still the most cost effective means of storing any real amount of power and it ROTS. R.I.P. the L16 we had a bad storm and I was working 12 hour shifts an a few 16 hour shifts Mrs B does not like to start the backup generator so the batt took a hell of a beating we were without power for 2 weeks. This is the reason for using the NAPA batt I can get them replaced within 24 hours.

Sweet Tatorman's picture

Ditto to what Mr B says about Lb-acid batteries still being the most cost effective chemistry for battery storage of bulk energy.

>While a battery may sit on a shelf charged for years, one that has to go through repeated discharging and recharging won't last as long.
Is that why you say not to use the batteries/electricity in an emergency set up like I'm thinking of?<

>Does the repeated cycles then decease the life expectancy from the batteries?<

Study the cycles vs DOD graph on either of the previously linked Trojan datasheets. That pretty much says it all. While there, also notice that those graphs only go down to 80% DOD. There is a reason for this. Lb-acid batteries are quite intolerant of being fully discharged and it doesn't take too many cycles of complete discharge to make them go South. Sounds like Mr B had some bad luck with his but I don't know the specifics of his situation. If his 10 cycles of below 50% DOD was 10 cycles to 100% then maybe reasonable result or it could be that he lives in a rather warm place. Alternately, just bad luck.
If you take the Trojan cycle life vs DOD graph at face value, notice the following. Reading to the closest 100 cycles, 20%DOD gets 4800 cycles and 80% gets 1200 cycles. In each case the total amount of energy stored and removed is the same. If you check any of the intermediate cycle vs DOD points you get [approximately] the same result for energy in and out. This type of relationship applies only to well designed deep cycles batteries and is definitely not true for automotive type batteries which are optimized for only very shallow discharges.
Regarding your chat with the battery tech:
>"While a battery may sit on a shelf charged for years"<
To be clear, what he means here is on the shelf and maintained continuously on a charger at appropriate float voltage level. If not kept on charge, Lb-acid batteries self discharge and the more time they spend in a partial state of discharge the faster they deteriorate. Proper maintenance of correct float voltage, which varies with temperature, is critical to achieving maximum standby life. Most other battery chemistries store better only partially charged and not maintained on a float charge. This is especially true of the Li-ion types.

Sweet Tatorman's picture

I'm sure that it was not me who previously commented on Chinese solar panel quality. I don't really have much basis to do so but I won't let that stop me since you have brought it up.

The Chinese solar industry has about 70% of the global market share including the non-Chinese companies that have their panels manufactured there and even higher if you include the panels manufactured in other countries using cells imported from China. You would really need to go out of your way to buy non-Chinese panels. Like many products there can be expected to be a range of quality. I'm told that you can buy solar panels at Harbor Freight so I would expect that there are some Chinese panels that are what I call "Harbor Freight quality", a polite descriptor used in lieu of some four letter ones of which "good" is not one. I have no reason to believe that many of Chinese panels are not of very good quality. I have seen many that where likely on low $/watt end of the spectrum and construction quality generally appeared to be good. This however tells me nothing about long term durability. Caveat emptor. I personally own several kW of Chinese made panels.

Blueberry's picture

I will let Tator Man explain about extending the life of lead acid batt. On your Dewalt Drill power packs it is possible to rebuild them. If the packs are NiCd or Ni-Mh the cell will have solder tabs just determine the size of the cell LWH and count the number. Just rebuilt a Led workshop-flashlight from HF Tools. The light was about 5 years old. The 3 cell in the light were 1.2 volts each at 800 millamps. the new ones are 1.2 volts at 2000 millamps. The light will run on full power for 6 hours. Good place for small batteries. This is the page for info on rebuilding power packs

mountainmoma's picture

I live off of a social security check, and have solar and a battery bank. We have frequent power outages during winter storms. I do not think batteries are expensive, I previously had 4 trojan 12V batteries, lead acid, the tall ones likely was L16 type mentioned upthread and this was plenty of backup power for at least 4 days refrigerator ( lights, toaster, electric kettle and other things used conservatively). I heat my house with a wood stove. I have 2Kw of panels installed 20 years ago and then 600W added about 10 years ago, so I figure even with any degradation a bit over 2kw panel output. My PV system is wired as a 48V system.

I will second, as mentioned above, do not draw on the lead acid batteries day to day, keep them charged up and use when the power is out.

So, financial considerations. I was not on limited income when the solar was put in, did not know I would get disabled. I am so glad for the solar, and many other things that keep my expenses low. This has allowed me to be able to stay here. Key money saving strategies: I have the solar electric, (I had solar hot water but a panel is leaking so not working now), I heat with wood stove, I do not have debt, and the house was on a 15 year mortgage so was soon paid off. I garden enough, etc.... Then, over many years on a cash basis, we converted a space to be a studio rental. I can live on the soc security without that, but it is good tp have right now to use the extra income for this round of house repairs and other preps. ( new solar batteries, caulking, painting, new woodstove, etc..... Kind of like settly your mare, get everything in working order now)

Blueberry's picture

David if you want to try and rebuild a power pack for your drill, I will be happy to send you some heat shrink tubing, 60/40 rosin core solder and some hookup wire. You have my email. All you will need are the cells (10 or 11) and a 30 to 40 watt solder gun. In a power outage you will find the little power packs useful, can be used for lighting, power for a cell phone or a tablet. Sorry no cold beer.

David Trammel's picture

Thank you but I have all that, lol.

I've seen the tutorials on disassembling drill power packs but haven't done it myself. That's on my to do list for tutorials on the "GW Book of Skills". I did bust open a battery once by dropping it from a high place on a movie shoot and know what's inside them.

Funny I own Dewalts because I've seen both Dewalt drills and Mikita drills in work and the Dewalts always had more power and lasted longer. Mikitas though were used alot when I worked special effects as battery packs for props. Most of the phaser rifles in both the Star Trek tv series and the movies, which I worked on were powered by 9v Mikita batteries. They had the advantage of being small and could be swapped out for recharged ones easily.

My current residence, a duplex gets amazing Sun, with a South side. I'm leaning towards doing another tutorial on solar power, where I put in a panel and wire it to a 12 volt battery powering one led light. My walk around the house lighting is two 20watt salt lamps, one in the office and one in the living room. Other than when I'm in the kitchen or bathroom, the rest of the lights are off. I wonder if i could replace the office light with a solar powered 12v lamp? I doubt it would affect my over all electric bill, which is tiny BUT it would be a fun thing to try.

Why Germans Are Buying Batteries With Their Solar Panels
Solar home storage has morphed from a niche product in Germany to one with enormous mainstream potential.
"Today, one out of every two orders for rooftop solar panels in Germany is sold with a battery storage system."

Blueberry's picture

Smart move for anyone living in Germany. In another post put a link about there power problems. Germany has built wind that should supply 130% of demand on a good day they get 10% of power from wind. Poland supplies around 30% of the power to Germany by burning coal. France supplies 40% from nukes. But Germany is so GREEN. The Germans are burning peat to make power.