Solar to be or not ?

[wanaberetiree]

I live in SF CA and thinking about going solar.

My average bill is +/-100$ with max in winter time ~150$

On one hand going green sounds like a noble goal, but we also want to address the issue to stay with power in case of outages.

Wonder if anybody has done this and wants to share feedback.

Thx

 

[ckelly78z]

While the idea of going solar is appealing to many folks, the actual numbers may prove not cost effective. How long will it take to pay off your system with lower bills (Your electric bill is already fairly low) ?

 

[wanaberetiree]

While the idea of going solar is appealing to many folks, the actual numbers may prove not cost effective. How long will it take to pay off your system with lower bills (Your electric bill is already fairly low) ?

Definitely a consideration.
But for this exercise we can say it's out of consideration.

 

[Retire52]

I just went through the exploring the idea phase. One tip is to get multiple quotes. It was a big spread and well worth the effort of obtaining 3 quotes.

For cost efficiency, I opted to wait until I need to replace my roof. I've got maybe 5 years or more left in it, then I plan to go solar.

 

[wanaberetiree]

I just went through the exploring the idea phase. One tip is to get multiple quotes. It was a big spread and well worth the effort of obtaining 3 quotes.

For cost efficiency, I opted to wait until I need to replace my roof. I've got maybe 5 years or more left in it, then I plan to go solar.

Good thx.

Did you get any idea on how long can you survive on a battery in case power outage ?

 

[Nature Lover]

Wanabe, In determining your project scope, make sure to inquire about whether you can connect/disconnect from the grid here in CA in the event of an outage. My understanding is that if you connect a solar system to the grid here, then the solar won't work when the grid is down. That would leave you with the option of a stand alone system with batteries (and no "sell" back to the grid if you produce more than you use).

I'm not knowledgable about how to configure a stand alone system to provide power for a specific need (and suspect that specific need would need to be regularly powered off-grid once the system is set up). Anyway, just a potential issue to explore while developing/reviewing options.

Maybe there's a "switch" that could connect/disconnect to the grid? I asked and got a muddled answer that was either "you can't do that" (meaning a violation of code), or "we won't do that" (because we just don't do those) - and I never really clarified since clearly the contractors were either experienced and it is not allowed, or not experienced with it and unwilling to consider it.

I'm in the SF Bay Area, and the cost/benefit of traditional solar just wasn't worth it without the ability to keep me powered during outages, and going off grid entirely wasn't a viable option. Once I found out traditional grid connected solar wouldn't provide significant backup power in the event of an outage/public safety power shutoff here, I was done.

NL

 

[travelover]

Good thx.

Did you get any idea on how long can you survive on a battery in case power outage ?

That is a complex question, which of course depends on what electrical loads you expect to run, how big of a battery you want to pay for and if the solar application allows it to provide power when the grid if off (some do).

 

[NW-Bound]

Good thx.

Did you get any idea on how long can you survive on a battery in case power outage ?

It depends on the size of the battery in the system, relative to what you are using. Same with how large a solar array you will need, and this also depends on your location (latitude, and cloud cover), and the orientation of the roof.

Start out with knowing how many kWh you typically use a day, and go from there.

 

[HI Bill]

With such a low power bill, a payback/cost-benefit analyis would likely show that at the end of the PV system's lifespan (currently around 15-20 years), you'd likely be at/near the break even point. I'm not sure about electrical codes and disconnects in CA, and whether a back-up battery can be online during a power outage. I'd think that to do so, you'd have to isolate the circuit.

I'd personally consider a back-up generator, with a transfer switch in your case. Unless you decide to get an electric car, in which case, the payback would be faster.

 

[NW-Bound]

Wanabe, In determining your project scope, make sure to inquire about whether you can connect/disconnect from the grid here in CA in the event of an outage. My understanding is that if you connect a solar system to the grid here, then the solar won't work when the grid is down. That would leave you with the option of a stand alone system with batteries (and no "sell" back to the grid if you produce more than you use).

I'm not knowledgable about how to configure a stand alone system to provide power for a specific need (and suspect that specific need would need to be regularly powered off-grid once the system is set up). Anyway, just a potential issue to explore while developing/reviewing options.

Maybe there's a "switch" that could connect/disconnect to the grid? I asked and got a muddled answer that was either "you can't do that" (meaning a violation of code), or "we won't do that" (because we just don't do those) - and I never really clarified since clearly the contractors were either experienced and it is not allowed, or not experienced with it and unwilling to consider it.

I'm in the SF Bay Area, and the cost/benefit of traditional solar just wasn't worth it without the ability to keep me powered during outages, and going off grid entirely wasn't a viable option. Once I found out traditional grid connected solar wouldn't provide significant backup power in the event of an outage/public safety power shutoff here, I was done.

NL

In the past, solar systems with battery storage were mainly off-grid systems and built by DIY'ers or hobbyists. And they tended to be in remote areas not serviced by a utility company.

Nowadays, there are commercial systems that can do both functions of a grid-tie system as well as a stand-alone storage in case the grid goes down. Tesla Powerwall is the most well-known example, but others exist.

You can check these out, but be forewarned that they are not cheap.

 

[Midpack]

I have to assume net metering may change, to be less advantageous to homeowners, not soon but eventually. It may be that solar homes are grandfathered (for 20 years?) with the net metering terms in place at the time of installation.

I'm asking, not telling. But it's a factor in breakeven analysis.

 

[NW-Bound]

I have to assume net metering may change, to be less advantageous to homeowners, not soon but eventually. It may be that solar homes are grandfathered (for 20 years?) with the net metering terms in place at the time of installation.

I'm asking, not telling. But it's a factor in breakeven analysis.

Yes.

In some places in the US, the UK, and Australia, they are dropping the old way of allowing the homeowner to pump electricity into the grid and then to be able to pull out the same kWh later. The reason for that is sound, that is peak solar production does not coincide with peak demand periods. One hour you have more electricity than anyone can use, and the next hour you do not have enough. One cannot bank the surplus power this way.

When there were few home solar systems, the above was acceptable, but they now have the situation where California had to pay Arizona to use some of the surplus electricity. I posted about this several times in the past.

Existing home systems are grandfathered, but with newly installed systems the homeowners may be paid only the wholesale price of their surplus power, at the time that is pumped into the grid.

With a home battery storage, instead of getting peanuts for their surplus power produced in the early hours of the day, the homeowner can store it himself for use later in the day, when electricity cost is higher. Thus, he gets more dollar value out of the same kWh that his panels produce, by saving it when he cannot use it, and using it later when it is worth more.

Some places including California have a rate schedule where the homeowner pays an additional penalty if his usage exceeds a certain threshold. The battery can be used for "peak shaving" by absorbing the power at low usage periods like at night, and releasing it in the mid-afternoon to offset the AC usage.

The only problem with using batteries for storage and peak-shaving is that the lithium battery wears out with each charge/discharge cycle. Tesla guarantees its Powerwalls for so many kWh of throughput, and the hardware has a built-in metering system to keep track of that, and to report back to Tesla.

Figuring out the cost effectiveness will take a bit of work. However, if one is using such a system for emergency power during periods of PSPS ("Public Safety Power Shutoff") because of high winds, the availability of the backup power is worth a lot more than the cost of the kWh. It is even harder to put a price on that.

 

[travelover]

If the OP's main concern is having power when the grid is down, there are lots of more cost effective ways to do that than adding solar panels.

A small $500 inverter generator will power lights and computers, for example.

 

[wolf]

Also, live in S.F. Bay area. Agree with many of the above posters.
Not cost effective.
Also, solar panel, do not last forever. And eventually need to be replaced.

 

[Souschef]

DW asked about it, and did some research. Our bill came out to about $1000/ year, so there would be a 15 year payback on the system. We really only have to protect against the grid being down.
SCE has a system where they shut down power if the winds are too high. How well does this work? Well they energized a 16 KV line on the mountain behind us and caused the Maria fire. We had to evacuate for one night!
Our solution to outages was to buy a 3600 watt generator. It was enough to power our refrigerator and a 6 cu ft freezer as well as our tv. We also had a power strip to charge our devices as well as our neighbors'.

 

[rk911]

Good thx.

Did you get any idea on how long can you survive on a battery in case power outage ?

you could always add a standby generator. is your area served by natural gas?

 

[DSC800]

I live in SF CA and thinking about going solar.

My average bill is +/-100$ with max in winter time ~150$

On one hand going green sounds like a noble goal, but we also want to address the issue to stay with power in case of outages.

Wonder if anybody has done this and wants to share feedback.

Thx

Here in San Diego with SDG&E (the worst) we've had 4.5kw solar for 4 years and very happy with it. It produces 100% of our needs and so far the climate credits have covered the minimum monthly bill. Initial outlay was $15k, after rebate the net was $10.5k. Our electric bill for our home + EV driving 10k miles a year would be around $2k/annual so the payback is just under 6 years. Without the EV we'd have installed a smaller system, but payback would be longer, closer to 8 years. Combining solar with an EV and not buying much gas is a real plus for saving money. They complement each other, but of course, the EV cost more. Another plus is that we use AC more without worrying about 50c kwh rates (our AC costs $2/hr in the summer).

For the battery backup, we didn't consider it. Not many outages around our area and I have a small generator to run critical stuff if needed. With the 50c/kwh peak shifting later to 4-9pm there could be a benefit for battery storage even without solar.

Oh, and there is a "feel good" factor. We cut our gasoline usage by 75% or over 200 gallons a year.

 

[Alan]

I have to assume net metering may change, to be less advantageous to homeowners, not soon but eventually. It may be that solar homes are grandfathered (for 20 years?) with the net metering terms in place at the time of installation.

I'm asking, not telling. But it's a factor in breakeven analysis.

As NW points out the UK does not have net metering. The company we signed up with has “agile” pricing where the tariff changes every half hour and is published every day in advance. Using the app IFTTT (if this then that) you can connect various devices to your account to do things like turn on the hot water boiler when the price drops below a certain value, or turn one or more of your Hue lights to red when the price goes above a certain value. Even our internet connected washing machine can be loaded and set to only come when the price is right. (Being retired we don’t really need that feature, although it is amusing to get an alert on the phone when a wash load finishes)

The excess electricity we generate we get paid the price on that half hourly tariff, and if the credit builds in the account. You can let the credit build to use against your winter gas bill, or have it deposited to your bank account (I did this end of August just to see how easy it was and it worked great). Our inverter has a forced export timer as well as a forced charge timer. This means we can charge during a cheap period and then discharge during an expensive time, useful during the winter.

A fully installed 4kW solar system here costs around £6k ($8k), adding battery storage (4kwh) adds another £2.5k.

 

[COcheesehead]

We bought our house with solar already installed and we really didn’t pay more based on comps. We do have a tech time bomb down the road if we stay here long enough if/when they need to be replaced, but the excess energy we generate pays for our gas usage, so overall at the end of the year we actually had about a $200 credit in our account. So our utilities are actually a money maker for us.

 

[folivier]

If you only want to power lights, fridge/freezer, fans, tv, etc. a battery storage system shouldn't be too expensive. However any large wattage items such as electric stove/oven, air conditioner, electric heater would need a huge battery system and larger solar system to recharge. In my motorhome I have 300 amp hours of LiPO batteries with 400 watts of solar and it is adequate in cooler climates. But certainly won't run an a/c or anything larger. But I do have some friends who have filled their roof with 1600 watts or more of solar and 1000+ amp hours of batteries and can run their a/c for a few hours.

 

[Offgrid Organic Farmer]

... Wonder if anybody has done this and wants to share feedback.

Thx

Millions of us have done it.

We shifted to solar-power in 2015.

I have a farm so our solar system in deductible. Using the straight-line method we can deduct 1/7th of the total expense against our income taxes for seven years. If you are depreciating the costs, your 'payback' can NEVER be longer than 7 years.

Our system is 'off-grid' with a battery-bank, which is smush less expensive than a grid-tied 'net-metering' system without battery.

We got three quotes before doing it.

Our system has 4400 watts of photovoltaic panels, with a 48vdc battery-bank with a 600ah capacity.

On average, by noon our battery-bank is topped off. So all the power we make from then until sunset is wasted. We can run every appliance in our house, and every power tool I own, and still not use all of the power we are making.

But once the sun sets, we must stop. Then we do very little as we must conserve power.

Also, live in S.F. Bay area. Agree with many of the above posters.
Not cost effective.
Also, solar panel, do not last forever. And eventually need to be replaced.

One of our neighbors built his solar power system in the 1980s, it is still powering his home.

Solar panels will last much longer than you or I will.



Now we drive plug-in hybrid sedans that re-charge from our household solar power system.

 

[MrsHaloFIRE]

I looked at it. the "payback" was right at 15 years on a roof install, and of course the selling back rate to the utility is microscopic compared to the purchasing rate from the utility. The utility also offered an option to purchase x number of panels offsite somewhere in town on undeveloped lots where they would install. Same type of payback period and offset. with the exception that if you move, as long as you stay with this utility of course you can keep benefitting from the offset.

 

[NW-Bound]

If you only want to power lights, fridge/freezer, fans, tv, etc. a battery storage system shouldn't be too expensive. However any large wattage items such as electric stove/oven, air conditioner, electric heater would need a huge battery system and larger solar system to recharge. In my motorhome I have 300 amp hours of LiPO batteries with 400 watts of solar and it is adequate in cooler climates. But certainly won't run an a/c or anything larger. But I do have some friends who have filled their roof with 1600 watts or more of solar and 1000+ amp hours of batteries and can run their a/c for a few hours.

It is a shame that roof-top motorhome ACs are about the least efficient that man can make. Well, most RV'ers do not live full-time in one, nor do they boondock, in order to care.

But I think it's about time RV manufacturers start installing inverter-type ACs, which are more efficient and also do not have a high inrush current during startup. The soft-start plus the variable speed feature makes it a lot easier to run the AC from batteries.

 

[zippy2020]

Be aware there are two types of mounts for solar panels on the roof, and one is considerably better/stronger than the other. Do your research (there's tons of articles since many people DIY).

We live in Oakland CA. We love our solar system but I would NOT recommend the OP get one any longer. Why? Because PG&E reached its maximum quota on NEM discounted systems two years ago. Solar systems installed subsequent to that cut-off do not benefit much money from sending excess power back to the grid.

The cost difference is considerable. PG&E currently credits us with retail price per kWH against what we use. We installed a 14-panel high-efficiency panel system and went live November 2014. Our bills dropped from $125+/mo to the $10/mo connection charge plus an amount that has varied between $7-12/mo ("true-up" is charged on an annual bill, so I mentally break it down to what the average monthly charge would be).

However, the difference between being credited with retail vs wholesale throws all the calculations out the window. Keeping in mind PG&E's tiered pricing and continual rate increases, on our true-up bill we are charged the cost of 23 cents per kWH for what we use over the solar kWH we generate.

My understanding (which may not be correct in the amount, but I believe is essentially correct) is that NEM aka 'net zero metering' credits us with that retail cost for all the solar power we send to the grid.

But new solar systems do not do that. New installs sending power to the grid are rated the same as all other power generators (commercial solar, natural gas, coal, water power) which varies in price from 4-7 cents per kWH.

So instead of being credited 23 cents or whatever your tier rate is, you will only receive a credit based on the wholesale price of energy at the time. You can see that this would vastly extend a break-even calculation.

Battery systems are separately priced. Most average home systems assume you want to run a few lights and your refrigerator/freezer. They do not, as pointed out by others, include heating. Figure $5-15K for the batteries, depending on the size of your home and how many panels you installed.

Most urban homeowners stay connected to the grid. Simpler and cheaper. If you want a whole-house battery system for backup, an installer can set it up to just be the flip of a switch.

Only you can decide if the high cost is worth it or not. For one thing, SF is as safe from wildfire hazards as is possible. And in an earthquake, fires are created by the gas lines and spread via structures close together. No battery back-up system can eliminate that.

I don't see that it's truly worthwhile UNLESS you were willing to be off-grid entirely, which will require lifestyle changes. And it still may not be able to work in a major quake. If you heat/cook with gas, for example, the utilities will shut off the gas AND the electricity in a major emergency. That's why restoration takes so long: electricity can be turned back on at the substations, but gas requires a PG&E installer to personally turn on EVERY individual residential gas connector in every affected area.

We've considered the cost of battery back-up. We plan to put in an AC system (having just had to replace the furnace, ugh) so in "brown out" situations and to ameliorate the high energy cost (as mentioned above by others), the battery system might work well for that. We get the most solar energy during the daytime, when AC is most needed inside our house - we get all day FULL sun, LOL. At night everything cools down so AC isn't needed here.

Other misc. issues:
- Our roof was only 3 yrs old when the panels were installed.
- Panels have a 25-30 yr lifespan, estimated.
- Inverter is the expensive recurring expense. They last 7-8 yrs and the cost is $700+.
- Install took over 3 mos. Panels went on in 2 working days, but inspections and having to satisfy the nitpickers delayed this to the 3+ month date.
- PG&E's bankruptcy has thrown ALL power contracts into disarray. There is absolutely no guarantee our own NEM contract will not be substantially amended by the judge. Until PG&E comes out of bankruptcy do not believe ANY sales rep, no matter who, that assures you "everything is fine, we'll honor your contract as written." The bankruptcy judge has ALL the power and PG&E can only offer its plan. Any contract is worthless if the judge decides to change the terms to satisfy the creditors.

HTH as you consider the addition of solar. At this stage I would say the cost benefits are solely with new construction only.

 

[NW-Bound]

Our system has 4400 watts of photovoltaic panels, with a 48vdc battery-bank with a 600ah capacity.

On average, by noon our battery-bank is topped off. So all the power we make from then until sunset is wasted. We can run every appliance in our house, and every power tool I own, and still not use all of the power we are making.

But once the sun sets, we must stop. Then we do very little as we must conserve power.

Now we drive plug-in hybrid sedans that re-charge from our household solar power system.

I have a 5.5-kW solar array feeding a 22.5-kWh lithium battery built from 1280 lithium cells of the 32650 physical format (each cylindrical cell is a bit larger than a common D cell). The entire system is DIY, and an off-grid system that does not feed the grid.

My home uses so much energy that it is rare that the solar array can top off the battery. In a hot summer day of 120F degree, and when the low temperature of the day at dawn is 90F, I used as much as 100 kWh/day, mostly for the central 5-ton AC.

I installed a 1.5-ton mini-split to provide auxiliary cooling for the 1st floor which has the living space and the master BR, and raised the thermostat of the central AC, and let the rooms upstairs get up to 85F.

The off-grid solar system was able to run the mini-split around the clock, except for the hottest days. The average daily consumption in July dropped from 85 kWh/day down to 44 kWh/day.

The saving of 41 kWh/day is not entirely due to the solar array, as it only produces about 20-25 kWh/day due to some shading. The rest is due to the use of the mini-split just to cool the downstairs (1700 sq.ft.), and let the empty upstairs (1000 sq.ft.) stays hot.

PS. My off-grid system can barely produce enough power to run the mini-split heat pump for cooling in the summer and heating in the winter. During the shoulder seasons in spring and fall when the temperature is moderate, the excess power is used for the water heater, the refrigerator, and some kitchen appliances.

I installed automatic transfer switches to switch some house circuits between the inverters and the grid as appropriate. The entire system of inverters, chargers, and battery racks is in a storage shed in the backyard. Solar panels are ground mounted.