Solar power (home aplication)

[MusclesMarinara]

Hello fellow home improvers, I'm looking into a solar panel system and house battery as we've begun to switch our services from direct fossil fuels to electric based equipment. We're making the move towards all electric as this equipment tends to be smaller and require less maintenance than there mechanical equivalents. Before anyone gets on me about air conditioning, I'm not installing a Peltier cooler. There isn't one now and will likely have to go in as a mini-split system.
So back on topic. Anyone have any thoughts or experiences with solar panels and house batteries. I would love to hear your thoughts.

 

[genecop]

I’m just starting to educate myself, this guy has it figured out and is a great source of info, he even sells a book..He is very advanced so some topics are hard to follow if your new to solar..

 

[TeTe]

We were considering the battery with the system, but realized it was a waste of money just to have one in case the power went out, which happens like once a year.

 

[MusclesMarinara]

We were considering the battery with the system, but realized it was a waste of money just to have one in case the power went out, which happens like once a year.

Understood and highly unlikely that you will freeze to death during those frigid San Diego winters. We live in a heavily wooded area just outside of NYC. We can get heavy wet snow from the end of October to early April. These snow snap these big old trees like toothpicks, which in turn lays waste to our outdated wooden pole based electric delivery system. It's not unheard of to lose power for a week. Finding a back up system Is fairly important for us..

 

[TeTe]

Understood and highly unlikely that you will freeze to death during those frigid San Diego winters. We live in a heavily wooded area just outside of NYC. We can get heavy wet snow from the end of October to early April. These snow snap these big old trees like toothpicks, which in turn lays waste to our outdated wooden pole based electric delivery system. It's not unheard of to lose power for a week. Finding a back up system Is fairly important for us..

lol fair enough, makes sense in your case then

 

[Protectandserve]

I have solar but not battery back up. They are still expensive as fuck for the batteries.

Price needs to come down significantly for me to get a battery as well.

Solar has been worth it for sure though

 

[boingyman]

I just installed 8.16kW Tesla solar panels on my home. 24 panels total. Past inspection last week, but still waiting for PTO (permission to turn on). Total cost is $18k, but after federal tax credit (26%) and making use of sign-on bonuses/points on credit cards (they let you pay with multiple credit cards) it will be a tad above $10k. No other company came close to the $18k price. In fact many local installers were double. I anticipate payback would be ~4 years.

I personally decided not to go with the battery (aka Powerwall) because I feel that it's not worth the price. We don't really get power outages (wires are underground) and I don't own an EV. Yes I know I could rely nearly 100% of my energy through solar if I got powerwalls, but still overpriced for my usage. Even if you have a electric car to fully charge you would need at least 4 powerwalls and then a higher percent offset meaning likely more panels. As the batteries get more efficient and cheaper I may get it down the road. Your case may be different of course.

With that being said research about your state/local existing solar program. In California we have something called NEM (currently NEM 2.0). Check to see what kind of ‘solar fees’ your electric company has if they do. Research what the buy back is for each kWh and true-up in your local area. Look at your daily and monthly electric usage and compare to the amount of panels you would need to offset that. I also recommend assessing your home. How old is your roof? How would the panels be laid out? Do you have anything that would cast shadows on your panels? Large trees? A chimney? How much sun do you get in your area? All these are factors to consider and more.

Here is my total production from a few days ago. 2 days ago I hit 57.7kWh, however yesterday had a lot of cloud coverage and was in the low 40s. Definitely making way more then we use.

 

[MusclesMarinara]

I think this is an approximation of what we are trying to do:

 

[MusclesMarinara]

I just installed 8.16kW Tesla solar panels on my home. 24 panels total. Past inspection last week, but still waiting for PTO (permission to turn on). Total cost is $18k, but after federal tax credit (26%) and making use of sign-on bonuses/points on credit cards (they let you pay with multiple credit cards) it will be a tad above $10k. No other company came close to the $18k price. In fact many local installers were double. I anticipate payback would be ~4 years.

I personally decided not to go with the battery (aka Powerwall) because I feel that it's not worth the price. We don't really get power outages (wires are underground) and I don't own an EV. Yes I know I could rely nearly 100% of my energy through solar if I got powerwalls, but still overpriced for my usage. Even if you have a electric car to fully charge you would need at least 4 powerwalls and then a higher percent offset meaning likely more panels. As the batteries get more efficient and cheaper I may get it down the road. Your case may be different of course.

With that being said research about your state/local existing solar program. In California we have something called NEM (currently NEM 2.0). Check to see what kind of ‘solar fees’ your electric company has if they do. Research what the buy back is for each kWh and true-up in your local area. Look at your daily and monthly electric usage and compare to the amount of panels you would need to offset that. I also recommend assessing your home. How old is your roof? How would the panels be laid out? Do you have anything that would cast shadows on your panels? Large trees? A chimney? How much sun do you get in your area? All these are factors to consider and more.

Here is my total production from a few days ago. 2 days ago I hit 57.7kWh, however yesterday had a lot of cloud coverage and was in the low 40s. Definitely making way more then we use.

Thanks for posting. If I could get a system with a battery installed for 30K I'd be happy. The 10K number you're reporting sounds like a dream. It might be worthwhile busting out that Lowe's card to take advantage of the discount.

The backside of the house is sun facing for the full day. However we do have some tree cover that will likely shade the panels at some point during the day. I don't want to remove the tree so we will have to accept the loss.

As far as sizing the system, I don't have a good handle. We aren't using much electric at this time. But you figure in electric heat or AC, that number will skyrocket. I'm planning on adding some Runtal electric baseboard this fall. Once that goes in, I can get a much better idea of what's happening.

 

[BlankaPresident]

I have a 5.1 kWp system in my house, string inverter as there is no shadows around. One of the best investments I've ever done.

No batteries here, we're still on grid.

 

[BlankaPresident]

About sizing, I recommend you to oversize it at least 20-25%. This way you don't have to be too conscious about AC use and we all will own an EV sooner or later.

 

[boingyman]

Thanks for posting. If I could get a system with a battery installed for 30K I'd be happy. The 10K number you're reporting sounds like a dream. It might be worthwhile busting out that Lowe's card to take advantage of the discount.

The backside of the house is sun facing for the full day. However we do have some tree cover that will likely shade the panels at some point during the day. I don't want to remove the tree so we will have to accept the loss.

As far as sizing the system, I don't have a good handle. We aren't using much electric at this time. But you figure in electric heat or AC, that number will skyrocket. I'm planning on adding some Runtal electric baseboard this fall. Once that goes in, I can get a much better idea of what's happening.

Look at electric cost and usage over the past year. If you can go back further even further. Then try to project future use. Sounds like you plan to add heating/cooling the home via electric, which will significantly increase your usage. Consider looking at other ways to make your home more energy efficient as well. If you have shadows microinverters may be better unless the string inverter has optimizers such as solar edge. Honestly in your case it may be best to have at least 2 reputable companies come in and do a solar assessment. It's usually free with no obligation. They will do all the leg work for you and then with that information you can shop around. I think that's your best bet. Do your research in advance, talk about your needs and have questions ready for them. Also keep in mind that batteries are expensive as hell right now and at least for powerwalls, they have been going up in price.

 

[freakroor]

Understood and highly unlikely that you will freeze to death during those frigid San Diego winters. We live in a heavily wooded area just outside of NYC. We can get heavy wet snow from the end of October to early April. These snow snap these big old trees like toothpicks, which in turn lays waste to our outdated wooden pole based electric delivery system. It's not unheard of to lose power for a week. Finding a back up system Is fairly important for us..

solar doesnt do much in the winter... get a backup generator.

source: i live in the woods and have solar power. in the winter we are lucky to pull 1kw from an 8kw system.

 

[ralphc1]

I looked into a solar system a few years back but didn't really look into a battery system. I'm at 45 degrees North Latitude so probably similar to you. In the winter, the sun is only visible for about 10 hours and is in the far southern sky so its dark for 14 hours. The angle that the sunlight comes through the atmosphere cuts the amount of radiation that makes it to the ground. It is cloudy about half of the time which further reduces the energy that it can produce. Snow makes it advantageous to have the panels more upright in the winter. So not much time to produce energy and a long time to need storage.

The most efficient solar system is one that tracks the sun so the panels are always perpendicular to its rays. I looked at one that tracks the sun and puts the panels in a vertical position at night. I was looking for enough capacity to cancel out my bill as the power company has to purchase any extra. With the tax incentives, it would have paid for itself in about 20 years. Since I'm retired, I don't pay enough taxes to claim it so it would be closer to 30 years payoff and I'm not likely to live that long.

Another thing to look at is the panel life. You might find companies that will give a 20 year warranty, but if the panels fail in less time, the company will file for bankruptcy and you'll be stuck.

 

[xHeadx]

Good advice in this thread. I'm interested as well so IN for knowledge.

 

[bigkick]

Great thread. Everything in our house is electric and we get a lot of sun, so it’s kind of a no brainer for us. I’d be stupid happy if we could get set up for under 20k though...

 

[GSP_37]

Are criminals known to steal your panels and battery right off your house?

 

[davidlemonparty]

You need to look at battery capacity vs your usage and you'll find you need a massive, massive, expensive battery bank that you will never be able to even partly charge off your solar.

Battery capacity is tiny relative to use. For a house that has a grid connection, there is basically no chance a battery makes sense practically or financially except for small duration intermittent blackouts (like less than 3 hours) .

A little diesel backup generator is what you need.

 

[davidlemonparty]

On the topic of solar panels, a couple of things to consider to help our your decision:
You can use the excellent PVwatts calculator https://pvwatts.nrel.gov/ and input in your roof details and some scenarios to show your usage over time. This uses real world data and is basically industry standard method to determine your true solar potential. Hit me up if you need assistance with inputting your deets.

The other thing you mention is shading - really important to understand how solar panels work. If you utilise a string inverter (IE several panels which are connected in series to a single input into your inverter) then shading on even one panel in that string will erode your total output massively. Its much worse than just 1 out of 20 panels being shaded = 5% impact.
Most inverters are string inverters, but you can get micro inverters where you have one small inverter per solar panel. These reduce shading impacts dramatically, but they are 20-30% more expensive overall.