Calculate for 3549 kWh per month

[Mike90250]

I've considered generators (gotten a couple of providers to come out and do estimates) and they would work great unless there comes a time when you cannot get propane or diesel

I see lots of folks that are off grid using batteries to store the juice collected by their solar system

Maybe they are only using their batteries for smaller appliances and aren't using AC, but none the less there are folks doing this totally off the grid

Batteries can't be totally useless since some folks are totally off grid using them.

Wife and I and farm with 300 fruit & nut trees, are totally off the grid, for the last 11 years.. There are some disadvantages. Limited electricity in the winter, can't use plug in heaters, limited microwave usage. Have to walk kerosene lamps to 4 outbuildings to keep greenhouses and pump house warm.
Summertime I pump water daily, about 2500 gallons from the pond to elevated storage tanks for irrigation.

Oh, and all was designed and planned for 2 years before buying anything. Small systems - you can afford to "seat of the pants". Large systems really need to be engineered by asking all the right questions before spending $$$

[robbyg]

I've considered generators (gotten a couple of providers to come out and do estimates) and they would work great unless there comes a time when you cannot get propane or diesel

I have actually experienced that for several months after a Hurricane hit in the 80s. I witnessed all the propane and diesel generators go down in the neighborhood after the first couple of days, but the Gas powered ones stayed up. You can always find Gas after a disaster but propane is impossible and Diesel is very difficult.

I see lots of folks that are off grid using batteries to store the juice collected by their solar system

Sure and you can do it to but your kind of sending mixed signals. Are you trying to save money using solar vs the Grid or are you prepping for some kind of disaster or is it both? If your Utility companies rates are low then batteries are never going to save you money. If your thinking of prepping for a disaster and have the cash then yes you can put up 60 panels, three big 12Kw Inverters and buy 90 KWh worth of batteries and you should be good to go. Keep in mind that will probably cost you nearly $120K installed, if not more. If your trying to do both things then I suggest a smaller amount of panels like maybe 30 and maybe a small amount of batteries like 20KWh worth and a single 12Kw Inverter. Then Invest the rest in a 10-15Kw Generator and a large underground Gas or Diesel fuel Tank.

Maybe they are only using their batteries for smaller appliances and aren't using AC, but none the less there are folks doing this totally off the grid

Batteries can't be totally useless since some folks are totally off grid using them.

Batteries, especially LIfePO4 are great but the price is not cheap. You can use cheaper Chinese B quality cell packs but it's still going to cost you at a minimum about $29K for 90KWh of lower grade packs to be delivered to your door and then comes the installation work and $$. You can Double that price if you Want Grade A cells by manufactures like Fortress, Blue Ion or others that are UL certified.

The question is what exactly is the goal and how much do you want to spend to achieve it?

[J.P.M.]

Sorry to have offended you... it may be best if you could not participate in the threads where I'm asking questions.

Thanks!

I'd respectfully suggest you disabuse yourself of the idea that you have the power to offend me.

You asked a question: "...so how do I go about seeing what equipment I would need to produce 3549 kWh per month...?

I offered some info and a couple of thoughts that might be helpful to consider to help your search.

I'd suggest you might also do something about self important attitude, your thin skin and also be careful what you ask for.

FWIW, your questions and comments so far could all have been addressed by the Dummies book either directly or by reference.

Best of luck in your future endeavors.

Take what you want of the above. Scrap the rest.

[SunEagle]

I have actually experienced that for several months after a Hurricane hit in the 80s. I witnessed all the propane and diesel generators go down in the neighborhood after the first couple of days, but the Gas powered ones stayed up. You can always find Gas after a disaster but propane is impossible and Diesel is very difficult.



Sure and you can do it to but your kind of sending mixed signals. Are you trying to save money using solar vs the Grid or are you prepping for some kind of disaster or is it both? If your Utility companies rates are low then batteries are never going to save you money. If your thinking of prepping for a disaster and have the cash then yes you can put up 60 panels, three big 12Kw Inverters and buy 90 KWh worth of batteries and you should be good to go. Keep in mind that will probably cost you nearly $120K installed, if not more. If your trying to do both things then I suggest a smaller amount of panels like maybe 30 and maybe a small amount of batteries like 20KWh worth and a single 12Kw Inverter. Then Invest the rest in a 10-15Kw Generator and a large underground Gas or Diesel fuel Tank.



Batteries, especially LIfePO4 are great but the price is not cheap. You can use cheaper Chinese B quality cell packs but it's still going to cost you at a minimum about $29K for 90KWh of lower grade packs to be delivered to your door and then comes the installation work and $$. You can Double that price if you Want Grade A cells by manufactures like Fortress, Blue Ion or others that are UL certified.

The question is what exactly is the goal and how much do you want to spend to achieve it?

If your generator is small or portable then yes propane may be hard to find during a long outage. What I felt was a better option is to get a whole house generator and at least a 100 gallon propane tank to run it in case of a long outage. The gen set should be sized to handle the entire home and the run time can be extended based on which loads you are running.

If you want to run the same loads for the same period your battery system will be huge and costly. For me during a hurricane we had a lot of rain and clouds which pretty much eliminated any production from solar so any batteries I had would be dead after a couple of days. Which is why I have a 12kw dual fuel gen set to help me cool my home here in Florida along with keeping my food and electronics running should I lose power for a long period. I can easily stock up on propane tanks beyond the 3 I have to keep it running for a pretty long time all at a cost of less then $2000.

[Droo71]

3500 kWh a month is a big number. I built my system three years ago, and I use about 10% of that in a month. Now, I'm offgrid so my battery is a limiting factor.

As a personal note, when I first joined, I had a fully designed system with all the math and numbers in it - and a question about charge rates for my battery. JPM , who's posting up above to tell you how uneducated and disrespectful you are -- well..... he was very disrespectful and critical of my question and my intentions and repeatedly called me out for my "ignorance of the solar resource". He was incredibly dismissive and rude. (and never even attempted to answer my initial, perfectly valid question.)
As it happened, my system has exceeded my conservative estimates by 15% consistently for three summers, and in fact, I *DID* know what I was doing -- quite consistently and correctly!!
Educating yourself in books and reading online is great - but I think there *CAN* be a lot of value in , as you are doing, asking others for their opinions. Don't let one guys attitude put you off a lot of the value in the site. I stopped posting for a long, long time because I didn't want to deal with this guy's attitude. I probably should have complained to a mod, but I mostly just left. Attitude's a sad thing on the net. I don't think wanting to maximize your ability to learn from other people's experience in a Q&A format is disrespectful, nor full of attitude - I think its smart.

For my off-grid system, I have a 3600W panel array in 3 strings of 4x300w panels; 790Ah forklift battery. I have a Magnum PT-100 Charge controller, and 2xMS4024 4000W inverters stacked in series , mounted on a Magnum MPSL Panel. Up to 8000W of power, and 120/240v to the panel. I don't need the 8000W at all. I do need the 240v for a couple of minor uses.

The array does produce more power than my charger can pass to the inverters in peak sun (the charger caps out at 2900W in charge/3200W equalizing).. but 90% of the time, the 'overpanelling' simply means i'm getting a healthy power intake. Comparing your charge controller capacity to panel/array size and being overpanelled is likely going to be important if you're trying to pull in 3500kWh a month. If you're doing a battery backup, this is going to matter; if you're just looking at daytime net-metering , it won't.

For usage, I use about 9 kWh a day from May to October; unused , just a float charge from Nov-Apr. The numbers fluctuate a bit, but my monthly usage is from 260-330 kWh / month. My charge controller is maxed out; you could double its intake by using 48V inverters, as its basically amp-limited; I think, though, that to get up to your monthly usage, you're looking at a *huge* system install. I'm also pulling about 40-45% out of the batteries (up to 370Ah) 7 days a week May-October, so about 170 cycles a year -- if you're using it full time, your cycle count will also be different.

What's your requirement look like for power output from the inverters? Sizing the inverters to match that daily output is probably also a good question for some of these guys; all the inverters I researched and now are 4000-4400W , because of my usage range. You're looking at 90kWh a day, though -- so a 4000W inverter isn't going to cut it.

[J.P.M.]

JPM , who's posting up above to tell you how uneducated and disrespectful you are -- well..... he was very disrespectful and critical of my question and my intentions and repeatedly called me out for my "ignorance of the solar resource". He was incredibly dismissive and rude. (and never even attempted to answer my initial, perfectly valid question.)
As it happened, my system has exceeded my conservative estimates by 15% consistently for three summers, and in fact, I *DID* know what I was doing -- quite consistently and correctly!!

The above from someone who seems to not know the difference between rude and attempts at reality talk.
I learned a long time ago that not everyone who tells me stuff I might not like is trying to belittle or hurt me.
Self important snowflakes seem to be more prolific as time goes on.
Ever stop to think that others besides yourself may benefit from my experience and postings even if your ignorance of the subject and thin skin hinder your ability to accept free, and more importantly, accurate information ?

As usual, take what you want of the above. Scrap the rest.

[Ampster]

No worries Droo71 the user statistics tell the story about how welcoming this site is despite the good efforts of some of the moderators. There are plenty of other places to get good information. I still visit every ocassionally because if you are patient and ignore the chaff there can be good information on some topics. Besides posting here does give me practice in dealing with my 87 year old sister who has become negative in her old age.

[SunEagle]

No worries Droo71 the user statistics tell the story about how welcoming this site is despite the good efforts of some of the moderators. There are plenty of other places to get good information. I still visit every ocassionally because if you are patient and ignore the chaff there can be good information on some topics. Besides posting here does give me practice in dealing with my 87 year old sister who has become negative in her old age.

Well maybe some of the members are tired of the same simple questions being asked that can be answered if they performed some simple reading and educating on the subject. I also get tired from DIYers that have no clue what they are doing yet want a full material list and installation package because they have heard about solar technology and want to participate yet may not even be able to put batteries in a flash light.

I will get off my soap box (preaching for those that do not understand what I said) and just say that anyone that expects full pleasantries and a totally Political Correctness on an open forum are just fooling themselves into believing they are entitled to free stuff without being told where they are wrong in their thinking.

As Ampster stated. There are many other forums out there that will provide you with "your answer" and not say that you are wrong in your beliefs. So maybe go visit them instead of being soo hurt from what you get here.

And as JMP states. "Take what you want above and scrap the rest"

[Droo71]

Well maybe some of the members are tired of the same simple questions being asked that can be answered if they performed some simple reading and educating on the subject. I also get tired from DIYers that have no clue what they are doing yet want a full material list and installation package because they have heard about solar technology and want to participate yet may not even be able to put batteries in a flash light.

I will get off my soap box (preaching for those that do not understand what I said) and just say that anyone that expects full pleasantries and a totally Political Correctness on an open forum are just fooling themselves into believing they are entitled to free stuff without being told where they are wrong in their thinking.

As Ampster stated. There are many other forums out there that will provide you with "your answer" and not say that you are wrong in your beliefs. So maybe go visit them instead of being soo hurt from what you get here.

And as JMP states. "Take what you want above and scrap the rest"

Just so I understand the context --

I showed up here with an *already completed* bill of materials, and a spot-on understanding of what my performance was going to be from the panels/array, what my wiring was going to look like , etc. I wasn't a DIYer without a clue -- the numbers I quoted in my post have been as perfect a reflection as one can get for 3 years of results - running from 13-17% *higher* than what I put in my post (noting that I had attempted to be 10-15% conservative. I think the results , more than you or JPM, show that I did it right).

I certainly didn't show up asking for a design, or equipment recommendations, or vague 'general thoughts'. I asked for a specific recommendation about array size vs. optimal amps for charging a specific size of battery bank, because the informaton I was finding had multiple conflicting answers.

No one even read my question. Certainly I didn't get JPMs vaunted experience to provide 'free, accurate information'.
I didn't ask for design work or free work from any members. I asked a charge rate question.

I got no answer. Instead, I got grilled on not understanding my loads (I did, and do), not understanding the available insolation (I had it right) and told that I was stupid, ignorant, and rude because I couldn't understand why I was so wrong . I provided all the numbers and math and asked where I'd made a mistake and got no answer there (obviously) -- I couldn't understand and no one could correct it because I *wasn't wrong*.

And you're telling me now that , well, I was new, and the OP is new, so we should expect and accept that kind of abuse from members who claim to be experts simply because they've been here longer? Because it doesn't take much reading between the lines. An expert would have been able to answer my question easily.

JPM might have been able to. He chose not to, and derailed the post with *unwarranted* criticism - and he was *dead wrong*.
And that abuse, it seems, is moderator sanctioned.

Just delete my account please. No one who knows what they are doing needs this forum at all.

[Ampster]

As far as I can tell, the goal of this site is to drive traffic to the referral site owned by the entity that covers the expense of operating this site. In that context we are just content providers to improve the flow of prospects to that referral site. DIYers are probably not good prospects for a referral to an installer anyway, but only the site owner would know. Every solar forum I participate in has its own unique style and expertise. It is nice to have choices.

[robbyg]

As far as I can tell, the goal of this site is to drive traffic to the referral site owned by the entity that covers the expense of operating this site. In that context we are just content providers to improve the flow of prospects to that referral site. DIYers are probably not good prospects for a referral to an installer anyway, but only the site owner would know. Every solar forum I participate in has its own unique style and expertise. It is nice to have choices.

Really!!!
What Entity or company is this linked to?

[Ampster]

Really!!!
What Entity or company is this linked to?

solar-estimate dot org if I am not mistaken. It used to show up but maybe not on my phone.The other affiliated site of Soar Review is listed at the bottom of this forum. There are overlapping Directors and perhaps ownership. I don't know the details but maybe one of the Moderators can clarify the relationships.

[J.P.M.]

[QUOTE=Droo71;n429381]

JPM might have been able to. He chose not to, and derailed the post with *unwarranted* criticism - and he was *dead wrong*.



Seems to me you don't know the difference between helping the curious and spoon feeding the lazy.

I choose to not be an enabler who makes things worse for folks who lack the self respect and curiosity to seek their own answers with help from those who have been in their shoes and situation.

I'd suggest you might think about your situation and consider learning or developing some humility.
You don't know as much as you might think you know.

Good luck.

[GeorgeF]

I'm not just thinking of saving money, but thinking of being able to run the whole house in the event the electric grid crashes or becomes so expensive / un-relable that switching to solar becomes a must.

For only backup you don't need solar. If you insist to use a huge expensive battery bank, just charge and float with an AC-charger. What ever you do, you need a generator cause of the limited energy stored in batteries.

[Ampster]

For only backup you don't need solar. If you insist to use a huge expensive battery bank, just charge and float with an AC-charger. What ever you do, you need a generator cause of the limited energy stored in batteries.

The OP said in the statement you quoted that one of his strategies was to offset electricity if the grid became to expensive. In that case solar could be a decent return.
Also there are alternatives to expensive batteries and there are configurations of LFP batteries available in Texas that do not have the limitations that you experience with Pb in your location. It all depends on where you are standing. BTW, I am not trying to convince you, but rather let other readers see the alternatives.