Emergency Solar Generator Build

[mike2881]

I have some questions regarding an emergency solar setup that I plan on building. I have enough money to purchase 2 x 100 watt mono solar panels (http://www.amazon.com/dp/B00BCRG22A/ref=cm_sw_su_dp), which includes a 30 amp PMW charge controller, branch connectors, and cables. I want to produce approximately 1000 watt hours per day, which would require 2000 watt hour battery capacity (using the 50% rule; calculation does not account for multiple days of operation). Therefore, my 12 volt battery bank would require 167 amp hours (2000/12). I plan on purchasing 2 x 105 amp hour batteries to store this energy. I live in NC and figured for 5 hours of sunlight. Please keep in mind this setup is only for emergency situations so I don't want to spend a great deal on it.

Questions:

1. Any suggestions, corrections, recommendations on my specs above?
2. What wattage power inverter is recommended for this setup?
3. I plan on building this as a portable setup on wheels and anything plugged in would be within 10 feet. The solar panels would be within 10 - 20 feet. What gauge wires do you recommend from the charge controller to the batteries? And what gauge wires to connect the batteries together? And what gauge wires from the batteries to the inverter?
4. Do you recommend fuses? If so, how many, where and what types?

New to this and looking for suggestions. Thanks in advance!

Mike

[sensij]

You won't get 5 kWh/m2/day (sun hours) in the winter, and even getting that in the summer is a stretch unless your panels have very good orientation, no shade, and you replace the PWM controller with MPPT. If you really need 1000 Wh with what you have, and you want it all year round, I think you'll need to double the size of your array.

[mike2881]

Thanks for the input sensij. When you say I should double the size of my array, are you referring to the panels or the batteries? My budget can only allow for 2 x 100 watt panels and keep in mind this is for emergency use only, so I don't plan on using it year round. Based on that, what do you recommend?

[Sunking]

Thanks for the input sensij. When you say I should double the size of my array, are you referring to the panels or the batteries? My budget can only allow for 2 x 100 watt panels and keep in mind this is for emergency use only, so I don't plan on using it year round. Based on that, what do you recommend?

No one gives a damn about your budget, nor should you if you want to use solar. Sky is the limit is what you chose to do with solar so quit belly aching about your budget and spend the bucks. That is the choice you made going solar.

No way are you going to generate 1 Kwh of usable power per day using 200 watts of panels and a 30 amp PWM controller. Never going to happen. Also buying two 12 volt batteries wiring them in parallel is just plain foolish and throwing money away. Of course using only a 2 day battery is pretty foolish as well because an event that knocks your power out for a day will most likely be a storm with over cast skies for a few days. WTF are you going to do after day 1? Spank the Monkey? . Simple, you will sit there in the dark and wished you had listened and bought a generator. For less money you could generate up to 70 times more usable power in a day

Not sure of you area and Sun Hours but just assuming a national average of 3.25 Sun Hours in winter, could be less, would require a 600 watt Panel with a 40 amp PWM if you wanted to go the expensive route using battery panels and PWM controller. Smarter money (not to bee confused with Smart) would be to use 450 watt Grid Tied Panels with a 40 amp MPPT controller.

Either way PWM or MPPT generates 35 amps of charge current. With 35 amps of charge current demands a minimum 12 volt 250 AH battery, and a maximum of 420 AH. Go below 250 AH and you risk plate corrosion and spewing acid out of the battery. Above 420 AH and you have a stratified battery. As for the battery you use 6 volt batteries, not 12. Something like a pair of 6 volt golf cart batteries like a pair of US Battery 6-Volt product line

But doing this with solar is a fools game. You can get a 3 Kwh generator for 1/2 the cost and will generate up to 70 times more usable power in a day. So screw your budget. Fools and their money will soon be parted from each other.

[Mike90250]

Thanks for the input sensij. When you say I should double the size of my array, are you referring to the panels or the batteries? My budget can only allow for 2 x 100 watt panels and keep in mind this is for emergency use only, so I don't plan on using it year round. Based on that, what do you recommend?

Your budget allows for a 4KW 3600rpm screamer genset and 100 gallons of fuel.

Otherwise, you calculate your "must have loads" and size the inverter to be 130% of the load. Then size the battery for the hours you need the load, then size the panels to recharge the batteries.

Any other way leads to failure

[mike2881]

Holy **** what's with the instant negativity!!!??? I stated that I am new and looking for an emergency setup with 2 x 100 watt solar panels. I think this section of the forum is just for that. Instead of recommendations for improvements or answers to any of my questions, I mostly received rude backlash responses as if I don't even belong here. You can both go **** yourselves. Mike90250, you don't have business being a moderator with replies like that, unless you want to rename the forum to Solar for Rich Pricks Only. I'm not on a dime budget, nor did I tell you how much I plan on spending for you to recommend a gas generator, just trying to set this up appropriately with 2 x 100 watt panels for an emergency situation. You are both assholes.

With that being said, I'd love to hear some actual feedback based on 2 x 100 watt panels.

[SunEagle]

Holy **** what's with the instant negativity!!!??? I stated that I am new and looking for an emergency setup with 2 x 100 watt solar panels. I think this section of the forum is just for that. Instead of recommendations for improvements or answers to any of my questions, I mostly received rude backlash responses as if I don't even belong here. You can both go **** yourselves. Mike90250, you don't have business being a moderator with replies like that, unless you want to rename the forum to Solar for Rich Pricks Only. I'm not on a dime budget, nor did I tell you how much I plan on spending for you to recommend a gas generator, just trying to set this up appropriately with 2 x 100 watt panels for an emergency situation. You are both assholes.

With that being said, I'd love to hear some actual feedback based on 2 x 100 watt panels.

Unfortunately those 2 x 100 watt panels and based on your location will not be enough for your power needs. At best you might get (after figuring losses and efficiencies) about 400 watt hours a day of charging which is not be enough to keep those 2 x 105Ah batteries happy.

To build a solar/battery system to deliver 1kWh daily all year long is about $3000. You could spend less by going with a smaller battery system and panel wattage but the battery life will not last more than a year or two.

The reality is that a solar/battery system is beyond most people's budget.

[mike2881]

Unfortunately those 2 x 100 watt panels and based on your location will not be enough for your power needs. At best you might get (after figuring losses and efficiencies) about 400 watt hours a day of charging which is not be enough to keep those 2 x 105Ah batteries happy.

To build a solar/battery system to deliver 1kWh daily all year long is about $3000. You could spend less by going with a smaller battery system and panel wattage but the battery life will not last more than a year or two.

The reality is that a solar/battery system is beyond most people's budget.

Thanks for the reply. I should restate my objective a bit to provide more clarity. I'm OK if the system does not produce 1000 watt hours as that was just based on my initial estimate, but would be definitely going with the 2 x 100 watt mono panels I provided in the URL above, so that is my constant. I'm trying to make this system somewhat mobile, so I'd prefer to use two batteries and take whatever hour wattage that gives me. Based on that, I'm looking for recommendations on battery sizing, wire gauges, inverter, and fuse(s) that would be appropriate for the 2 panels for best results.

[SunEagle]

Thanks for the reply. I should restate my objective a bit to provide more clarity. I'm OK if the system does not produce 1000 watt hours as that was just based on my initial estimate, but would be definitely going with the 2 x 100 watt mono panels I provided in the URL above, so that is my constant. I'm trying to make this system somewhat mobile, so I'd prefer to use two batteries and take whatever hour wattage that gives me. Based on that, I'm looking for recommendations on battery sizing, wire gauges, inverter, and fuse(s) that would be appropriate for the 2 panels for best results.

Ok with that 30amp PWM charger I might guestimate that each of those 100 watt panels have an Imp ~ 5.5 amps. So with 2 you have about 11 amps of charging for a specific period of the day which gets shorter during the winter and hopefully longer during the summer. You need to find the insolation sun (no shade) hours for your area because 5 hours is not what you will get in the Winter.

With 11 amps of charging your battery system should not be less than 90Ah (C/8) and not more than 135Ah (C/12). So lets pick somewhere in the middle and say 105Ah.

A 12v 105Ah battery system can provide about 315 watt hours using only 25% of the full charge. Going more than 25% on a daily basis will shorten the lifespan dramatically so forget about what you read using 50% of a FLA battery. It is wrong.

Unfortunately with only a 105Ah battery you can use maybe a 300 watt inverter. Going with a larger wattage inverter runs the risk of using too much of the battery in a shorter period of time.

So while you won't need fuses between the panels and CC you should install a 30amp fuse between the CC and battery and a second fuse between the battery and inverter. The fuses are there to protect the wire, not the CC or inverter. So make sure your wire size can handle more amps then your fuse by a factor of 1.25%.

Hope that gets you started.

[sensij]

Based on a C/10 rule of thumb for charge current, those two panels, wired in parallel, will provide a max of 11 amps of charge current, usually less. 11 amps * 10 = 110 Ah FLA battery (12 V).

Wire the panels in series, you could go with 24 V, 55 Ah FLA battery.

Depending on the actual panel orientation and local weather conditions, you might find that an even smaller battery would be more appropriate, down to C/8 (~90 Ah) or even slightly smaller. As SunEagle suggested, if you can limit your "emergency" load to 400 Wh daily or less, you might have a chance. If this is really meant to be an emergency system, consider a generator as well (as Mike suggested), because I don't think you can count on emergencies happening on only sunny, summer days.

Edit... didn't see SunEagle's response before I posted, but am glad we are both pretty much saying the same thing.

[Sunking]

Holy **** what's with the instant negativity!!!???

It takes an Attitude Adjustment upside the head with a 2 x 4 to wake you up back to reality.

DO WE HAVE YOUR ATTENTION NOW?

With your 200 watt panels and a 15 amp PWM controller can support a 12 volt 100 AH battery. A 12 vot 100 AH battery can support a small Toy Size 150 watt mobile inverter. Enough for you to charge your cells phones and a laptop each day. There is your reality check. You could do that right in your vehicle with no Inverter, just use your cell phone USB charger and your 12 volt Brick PS for your laptop. No solar, charge controller, or battery required. Just run the engine 15 minutes.

Otherwise you are just pissing in the wind, fooling yourself, and throwing good money away. Good Luck with that. I would tell you to go F yourself, but you have already done that.

[SunEagle]

It takes an Attitude Adjustment upside the head with a 2 x 4 to wake you up back to reality.

DO WE HAVE YOUR ATTENTION NOW?

Ouch. I hate those splinters I get from 2 x 4s.

[Sunking]

Ouch. I hate those splinters I get from 2 x 4s.

You need to get to know Roy Damn Mercer

.

[mike2881]

It takes an Attitude Adjustment upside the head with a 2 x 4 to wake you up back to reality.

DO WE HAVE YOUR ATTENTION NOW?

With your 200 watt panels and a 15 amp PWM controller can support a 12 volt 100 AH battery. A 12 vot 100 AH battery can support a small Toy Size 150 watt mobile inverter. Enough for you to charge your cells phones and a laptop each day. There is your reality check. You could do that right in your vehicle with no Inverter, just use your cell phone USB charger and your 12 volt Brick PS for your laptop. No solar, charge controller, or battery required. Just run the engine 15 minutes.

Otherwise you are just pissing in the wind, fooling yourself, and throwing good money away. Good Luck with that. I would tell you to go F yourself, but you have already done that.

OK, I'm new to this and was looking for input on if my idea was worth the effort, hence the reason for having forums. Why are you all such moody little bitches (except for sensij who didn't directly attack me)? Maybe you all need to take a break from solar forums and get ****ed once in a while. I bet none of you would say this **** to my face because you'd be on the floor. Nice to have the protection of the internet between us, eh? Bunch of punks. In all seriousness, you really are moody little bitches. G'day <expletive deleted>!

---Mod Note: Please keep it clean (and don't let the door hit you on the way out.) Most of the members are quite helpful, and if you had bothered to read the Forum for awhile before posting you would know that. There are a few members who take "tough love" to an extreme, but are really quite helpful once you get past that point. I do hope that you reconsider your decision.

[inetdog]

Before you can get any really helpful advice you need to define "emergency" better. If you mean for a few hours or even a few days, then the battery bank, inverter, generator solution without the complication of solar PV really makes sense. If you want to go with PV, then as mentioned size your inverter and batteries to the expected load and duration (using some of the Off Grid sticky threads to help you.) Then decide whether you need to be able to recharge the battery bank from PV or not, and over what time scale.
If you will not actually be off grid for months at a time, the design factors will be different.
When you add in the idea of making it mobile you bring up a whole different can of worms, and low cost becomes very hard to achieve.
Do you want a system that you can afford which will be useless or do you want to do the best you can with your money?