Solar "generator"

[joebu37]

Hi all- I've been lurking here for a while getting tips tips for my solar generator project; now I'm done, and I wanted to get your thoughts.

I was hit hard by Sandy in northern NJ, and we were without power for a week; i know others had it bad, but it did suck with my wife, two young kids, and my mom, who's home was damaged. So I started researching generators, and ended up liking solar. I found out what you all know, the the so called "all in one" solar generators are complete BS; overpriced with minimal power return. So after so much research, I suddenly realized that I had absorbed enough information to give it a try on my own.

A couple of things; I did not do this under the guise of saving money; I have seen some of the posts people make where they think they are going to get a couple of batteries and panels ans get "free" electricity (and how you all try to talk sense to them). This project was entirely to create an emergency "backup" system, to which I have succeeded quite well.

So I put together-
4 Helios 300 w panels; pairs connected in series then in parallel at combiner box
Morningstar/Tristar MPPT 45 charge controller
6 VMAXSLR175 175 AH 12v batteries; pairs in series, then each pair to each other in parallel for three 24v batteries @ 175 AH each, giving me a 24v 525 AH bank
Samlex 3000w pure sine wave inverter

So I think I've come up with a tight little backup system here, what do you guys think? The whole thing cost me under 7k, and gets me at LEAST twice the power of a "generator" at that price.
We've lost power twice since I installed it, and it's worked great. I run my extra fridge on it during the week. I'm thinking of having an electrician put in a critical load box so I don't have extension cords all over; what are your thoughts on that?
Also, if anyone has any experience with the VMAX batteries; I couldn't find a lot on them, but the price from Amazon plus free delivery was too good to pass up.

Thank you!
Joe

[SunEagle]

Hi all- I've been lurking here for a while getting tips tips for my solar generator project; now I'm done, and I wanted to get your thoughts.

I was hit hard by Sandy in northern NJ, and we were without power for a week; i know others had it bad, but it did suck with my wife, two young kids, and my mom, who's home was damaged. So I started researching generators, and ended up liking solar. I found out what you all know, the the so called "all in one" solar generators are complete BS; overpriced with minimal power return. So after so much research, I suddenly realized that I had absorbed enough information to give it a try on my own.

A couple of things; I did not do this under the guise of saving money; I have seen some of the posts people make where they think they are going to get a couple of batteries and panels ans get "free" electricity (and how you all try to talk sense to them). This project was entirely to create an emergency "backup" system, to which I have succeeded quite well.

So I put together-
4 Helios 300 w panels; pairs connected in series then in parallel at combiner box
Morningstar/Tristar MPPT 45 charge controller
6 VMAXSLR175 175 AH 12v batteries; pairs in series, then each pair to each other in parallel for three 24v batteries @ 175 AH each, giving me a 24v 525 AH bank
Samlex 3000w pure sine wave inverter

So I think I've come up with a tight little backup system here, what do you guys think? The whole thing cost me under 7k, and gets me at LEAST twice the power of a "generator" at that price.
We've lost power twice since I installed it, and it's worked great. I run my extra fridge on it during the week. I'm thinking of having an electrician put in a critical load box so I don't have extension cords all over; what are your thoughts on that?
Also, if anyone has any experience with the VMAX batteries; I couldn't find a lot on them, but the price from Amazon plus free delivery was too good to pass up.

Thank you!
Joe

Your system may work for you but it seems the balance of panel wattage compared to battery Ah is high. Also the battery Ah compared to inverter wattage is a little low.

As for your comment concerning the cost of your system compared to a generator. I can get an 8000 watt propane generator installed for about $3500. That is half what you paid for the solar battery system and 2 1/2 times the wattage.

[russ]

I am still curious about what a "solar generator" is - does it generate suns or what.

Close to where I am in India at present there is a plant named Gujarat State Energy Generation - I thought they had gas turbines there but maybe it is some top secret thing where they are trying to generate energy?

Or maybe the guy that named the plant had no idea what he was naming.

[PositiveDude2000]

I am still curious about what a "solar generator" is - does it generate suns or what.
.

A solar generator is a device that converts solar energy into electrical energy.

You are the perfect mod for this site russ. Now go to the coroner with your pointy hat.

[joebu37]

Your system may work for you but it seems the balance of panel wattage compared to battery Ah is high. Also the battery Ah compared to inverter wattage is a little low.

As for your comment concerning the cost of your system compared to a generator. I can get an 8000 watt propane generator installed for about $3500. That is half what you paid for the solar battery system and 2 1/2 times the wattage.

Thanks for your reply. Absolutely agree about the propane generator, but I went with solar partial for the noise, but mostly because I like the fact that I can expand and grow it. Not to mention that I am fascinated by alternative energies and I enjoyed taking up the challenge myself.

As for panel to battery, (and forgive me if I don't get all the terminology correct; I'm still getting all that down) if I'm using the standard 20% of the battery power, that's 2520 Wh which I easily generate on a good day from the panels. I might not have a lot of wiggle room for rainy days, but this is for emergency power, and it's fine for what i need to run in an outage. Unless I misunderstood you- because I'm not sure what you mean by the battery Ah being too low for the inverter wattage. Can you elaborate? I welcome your input.

Joe

[SunEagle]

Thanks for your reply. Absolutely agree about the propane generator, but I went with solar partial for the noise, but mostly because I like the fact that I can expand and grow it. Not to mention that I am fascinated by alternative energies and I enjoyed taking up the challenge myself.

As for panel to battery, (and forgive me if I don't get all the terminology correct; I'm still getting all that down) if I'm using the standard 20% of the battery power, that's 2520 Wh which I easily generate on a good day from the panels. I might not have a lot of wiggle room for rainy days, but this is for emergency power, and it's fine for what i need to run in an outage. Unless I misunderstood you- because I'm not sure what you mean by the battery Ah being too low for the inverter wattage. Can you elaborate? I welcome your input.

Joe

I do understand the desire to have power and not have noise at night. I have both generators and a solar battery system (which I would use at night) in case of a power outage after a hurricane.

I'll retract my statement about the panel wattage being high as compared to the battery Ah. I wasn't thinking about the little amount of sun you can get during the Winter so your 1200 watts with a few hours of good sunlight is ok. You just don't want to charge your batteries too quickly and too much panel wattage can do that if you are not careful staying within your batteries charge rate spec.

As for the battery Ah being a little low for your inverter. Usually an inverter has a continuous and surge wattage rating. The surge rating on your inverter is 6000 watts which could quickly run down your batteries depending on how many times your load peaks. If you are not aware of how often you use those peak loads and if you don't keep an eye on your battery, you could run them down quicker than expected. Just keep your loads to around 3000 watts and you should be good to go.

[Naptown]

Your system may work for you but it seems the balance of panel wattage compared to battery Ah is high. Also the battery Ah compared to inverter wattage is a little low.

As for your comment concerning the cost of your system compared to a generator. I can get an 8000 watt propane generator installed for about $3500. That is half what you paid for the solar battery system and 2 1/2 times the wattage.

Panels are capable of producing almost a c/10 charge rate (assuming MPPT controller).

Thanks for your reply. Absolutely agree about the propane generator, but I went with solar partial for the noise, but mostly because I like the fact that I can expand and grow it. Not to mention that I am fascinated by alternative energies and I enjoyed taking up the challenge myself.

As for panel to battery, (and forgive me if I don't get all the terminology correct; I'm still getting all that down) if I'm using the standard 20% of the battery power, that's 2520 Wh which I easily generate on a good day from the panels. I might not have a lot of wiggle room for rainy days, but this is for emergency power, and it's fine for what i need to run in an outage. Unless I misunderstood you- because I'm not sure what you mean by the battery Ah being too low for the inverter wattage. Can you elaborate? I welcome your input.

Joe

That inverter is big in that it could allow almost a C/4 discharge rate at full capacity
When this happens Peukerts law will bite you big time.
To get full battery capacity you can only discharge at the 20 hour rate or C/20 rate
At C/4 your battery capacity is much lower than the rated size you quoted

[joebu37]

I do understand the desire to have power and not have noise at night. I have both generators and a solar battery system (which I would use at night) in case of a power outage after a hurricane.

I'll retract my statement about the panel wattage being high as compared to the battery Ah. I wasn't thinking about the little amount of sun you can get during the Winter so your 1200 watts with a few hours of good sunlight is ok. You just don't want to charge your batteries too quickly and too much panel wattage can do that if you are not careful staying within your batteries charge rate spec.

As for the battery Ah being a little low for your inverter. Usually an inverter has a continuous and surge wattage rating. The surge rating on your inverter is 6000 watts which could quickly run down your batteries depending on how many times your load peaks. If you are not aware of how often you use those peak loads and if you don't keep an eye on your battery, you could run them down quicker than expected. Just keep your loads to around 3000 watts and you should be good to go.

Thanks SunEagle. On the panel wattage, one of the reasons I went with the Morningstar was because of what a good job it does controlling the charge. Also, as I said in my other post, I designed the layout to be easily expandable. I hope to one day grow my system to power most of my home (less the AC, of course).

Yes, I agree about the inverter; I don't run anything crazy off of it, I just wanted the extra power if needed; and again, to grow into it.

I am fully aware of many of the misconceptions people can have about what they can get from solar power. I am trying to convey that to regular (non-solar educated) people that have an interest in solar.

Thanks again for your feedback.

Joe

[joebu37]

Panels are capable of producing almost a c/10 charge rate (assuming MPPT controller).



That inverter is big in that it could allow almost a C/4 discharge rate at full capacity
When this happens Peukerts law will bite you big time.
To get full battery capacity you can only discharge at the 20 hour rate or C/20 rate
At C/4 your battery capacity is much lower than the rated size you quoted

Thank you Naptown; very interesting. I am not knowledgeable on this. I basically got the large inverter to "grow" into it; I'm not putting any demands on it currently that would warrant a rapid discharge, nor even come close to the 6000W surge. Does my explanation make it sound better, or is the large inverter size just plain risky with the lower battery capacity?

Thank you!
Joe

[Naptown]

Thank you Naptown; very interesting. I am not knowledgeable on this. I basically got the large inverter to "grow" into it; I'm not putting any demands on it currently that would warrant a rapid discharge, nor even come close to the 6000W surge. Does my explanation make it sound better, or is the large inverter size just plain risky with the lower battery capacity?

Thank you!
Joe

You need to look at the inverter efficiency curve.
Too large an inverter will waste too much power just sitting there.
Inverters like to be run close to maximum load at max load they are most efficient.
Too big an inverter will cause a lot of standby losses when idling along at less than max output.

[FloridaSun]

You need to look at the inverter efficiency curve.
Too large an inverter will waste too much power just sitting there.
Inverters like to be run close to maximum load at max load they are most efficient.
Too big an inverter will cause a lot of standby losses when idling along at less than max output.

Which is why it makes more sense to me to start out with a small inverter to match battery capacity when starting out. If an when a larger battery bank is acquired the smaller inverter can always be used for lighting, etc, small loads, and a larger one purchased for the larger loads. Makes the whole system more efficient.

[joebu37]

You need to look at the inverter efficiency curve.
Too large an inverter will waste too much power just sitting there.
Inverters like to be run close to maximum load at max load they are most efficient.
Too big an inverter will cause a lot of standby losses when idling along at less than max output.

Thanks again; reading up on Peukert's law now.