Newbie - Wannabe Solar Guy

frizzz

I've been looking around for a while and decide to say HI.

The bad news is I live in northwest Oregon (low sun hours).
I'm looking at building a small off the grid solar system to supply enough power for at least this -

5 led bulbs of 10w
3 Cell phone
Laptop computer
Small Radio
Coffee Maker

I was thinking of

Two - T105RE 225 AH
http://www.solar-electric.com/trt16vo225ah1.html

Two - Kyocera KD140GX-LFBS 140 Watt 12 Volt Solar Module
Max Rated Power (Pmax) 140 Watts
Voltage at Max Power (Vmpp) 17.7 Volts
Current at Max Power (Impp) 7.91 Amps
Open Circuit Voltage (Voc) 22.1 Volts
Short Circuit Current (Isc) 8.68 Amps
http://www.solar-electric.com/kyocera-kd140gx-lfbs-140-watt-polycrystalline-solar-panel.html

ProStar 30 Amp Solar Charge Controller, 12/24 Volt With Digital Meter0
http://www.solar-electric.com/ps-30m.html

Midnite Solar MNPV3 3-Circuit Solar Array combiner. (not sure if I even need this).
http://www.solar-electric.com/mnpv3.html

I'm I looking at the right combination of parts or what is it going to take to keep a pair of T105re 225AH happy.

Cariboocoot

Re: Newbie - Wannabe Solar Guy

Welcome to the forum.

Okay let's put the financial brakes on here and take a look at a couple of basic flaws.

First, supply power to these items for how long? Knowing the Watt hours is essential to getting everything right.

Second, coffee maker? We're talking 1,000+ Watts there, and even if for a short time it needs a bigger inverter and battery bank to kick out that power than do all those other things put together.

The first thing you want to buy is a Kill-A-Watt meter: measure loads, don't guess at them. it will save you a lot of headache and grief.

simagic

Re: Newbie - Wannabe Solar Guy

use something like or similar to this to make your coffee. Uses no wattage ( assuming you have means to make hot water).. http://www.sweetmarias.com/sweetmarias/coffee-brewers/filtercones.html?source=side

westbranch

Re: Newbie - Wannabe Solar Guy

Ah, Yes, the Melita Coffee filter! http://www.melitta.ca/filters/cone-filter-paper

well known up here, but it needs boiling water, though the kettle may be more efficient than the aforementioned 'coffee maker'... probably a drip type.

frizzz

Re: Newbie - Wannabe Solar Guy

Okay let's put the financial brakes on here and take a look at a couple of basic flaws.

First, supply power to these items for how long? Knowing the Watt hours is essential to getting everything right.

Second, coffee maker? We're talking 1,000+ Watts there, and even if for a short time it needs a bigger inverter and battery bank to kick out that power than do all those other things put together.

The first thing you want to buy is a Kill-A-Watt meter: measure loads, don't guess at them. it will save you a lot of headache and grief.

5 led bulbs of 10w - 5 hour each = 250w hours
3 Cell phone - 3 hours each @ 2w = 18w hours
Laptop computer - 3 hours @ 25w = 75w hours
Small Radio - 1 hour = 2w hours
Coffee Maker - This is off my list - 3 cups of coffee for 598w no thanks.

Cariboocoot

Re: Newbie - Wannabe Solar Guy

So if you add it all up you get 345 Watt hours AC.

Now let's see how that looks in terms of battery:

345 / 0.9 (efficiency of inverter) = 383.3 (round up) 384 Watt hours.
Using a good, small inverter like the Morningstar 300 you'd add perhaps 12 hours 'on' (if things weren't run at the same time) or at least 5 hours (longest time any one item is used) @ full power of about 6 Watts: 30 to 72 Watt hours. While nothing is on you can shut it off or leave it in standby mode.

Let's use the biggest number and add it in: 456 Watt hours from the batteries. At 12 Volts, that's 38 Amp hours. Go for the standard 25% DOD and you get a battery bank of 152 Amp hours @ 12 Volts. That is pretty easy to supply. You'll probably need to round up again to get an available size like this: http://www.solar-electric.com/cr185am12vod.html 185 Amp hours.

Once the battery is determined it comes down to charging it. Normally you'd pick enough panel to supply 10% of the capacity in peak current. Since this is going to be <20 Amps, you can use a PWM type controller and about 324 Watts of panel.

Now there's some flexibility to that according to how the power is used. If you don't need all that stuff on while charging the peak charge rate can be reduced to fit available panels. For instance two KD 140 panels would produce 15.8 Amps, or 8.5% peak rate which would certainly do. You could also use two 130 Watt Solartech panels like this: http://www.solar-electric.com/solartech-spm130p-s-n-130-watt-multicrystalline-solar-module.html Again, 14.7 Amps or 7.9% peak rate - still viable.

And of course you'd need a charge controller capable of handling the current. One example: http://www.solar-electric.com/ss-20l.html

See how it comes together?

icarus

Re: Newbie - Wannabe Solar Guy

Can the coffee maker. Use a French press, or a melita cone or a Coleman stove top "Mr Coffee".

Tony

simagic

Re: Newbie - Wannabe Solar Guy

icarus wrote: »

Can the coffee maker. Use a French press, or a melita cone or a Coleman stove top "Mr Coffee".

Tony

The way this works is "YOU" slowly pour/drip hot water over you ground coffee in the same manner as a drip style coffee maker "drips" water over the grounds. Read the info and if you dig deeper on that link you will see videos

icarus

Re: Newbie - Wannabe Solar Guy

I certainly understand how manual pour and even auto mic drip coffee makers work. I was simply suggeting that heating the water from PV especially smal scale is not a very good idea.

Icarus

Cariboocoot

Re: Newbie - Wannabe Solar Guy

icarus wrote: »

I certainly understand how manual pour and even auto mic drip coffee makers work. I was simply suggeting that heating the water from PV especially smal scale is not a very good idea.

Icarus

Right as usual Tony.

I mean he could get a big MSW inverter that would supply 1000+ Watts just for the coffee maker (providing it doesn't have any electronics in it that couldn't handle the MSW) in addition to a good one for the small things (phone chargers may not like MSW, and why power a big inverter whena litle one will do?) but then he'd still need a battery bank capable of putting out the ~100 Amps @ 12 Volts while the coffee is being brewed and enough panel to recharge said battery bank. So he'd have to "size up" the system considerably just to handle a few minutes of brew time every day.

There's easier and cheaper ways to do it, just as you said.

NorthGuy

Re: Newbie - Wannabe Solar Guy

Cariboocoot wrote: »

There's easier and cheaper ways to do it, just as you said.

For example, this thing will make a very nice coffee.

frizzz

Re: Newbie - Wannabe Solar Guy

So if you add it all up you get 345 Watt hours AC.

Now let's see how that looks in terms of battery:

345 / 0.9 (efficiency of inverter) = 383.3 (round up) 384 Watt hours.
Using a good, small inverter like the Morningstar 300 you'd add perhaps 12 hours 'on' (if things weren't run at the same time) or at least 5 hours (longest time any one item is used) @ full power of about 6 Watts: 30 to 72 Watt hours. While nothing is on you can shut it off or leave it in standby mode.

Let's use the biggest number and add it in: 456 Watt hours from the batteries. At 12 Volts, that's 38 Amp hours. Go for the standard 25% DOD and you get a battery bank of 152 Amp hours @ 12 Volts. That is pretty easy to supply. You'll probably need to round up again to get an available size like this: http://www.solar-electric.com/cr185am12vod.html 185 Amp hours.

Once the battery is determined it comes down to charging it. Normally you'd pick enough panel to supply 10% of the capacity in peak current. Since this is going to be <20 Amps, you can use a PWM type controller and about 324 Watts of panel.

Now there's some flexibility to that according to how the power is used. If you don't need all that stuff on while charging the peak charge rate can be reduced to fit available panels. For instance two KD 140 panels would produce 15.8 Amps, or 8.5% peak rate which would certainly do. You could also use two 130 Watt Solartech panels like this: http://www.solar-electric.com/solart...ar-module.html Again, 14.7 Amps or 7.9% peak rate - still viable.

And of course you'd need a charge controller capable of handling the current. One example: http://www.solar-electric.com/ss-20l.html

See how it comes together?

I'm losted here.

Let's use the biggest number and add it in: 456 Watt hours from the batteries. At 12 Volts, that's 38 Amp hours. Go for the standard 25% DOD and you get a battery bank of 152 Amp hours @ 12 Volts. That is pretty easy to supply. You'll probably need to round up again to get an available size like this: http://www.solar-electric.com/cr185am12vod.html 185 Amp hours.

Excuse my ignorance but I'm from a public education system from the 70's. I understand 12*38=456 but how do you get 456 watt hours from batteries and where does the 38 Amp hour come from.
I think I need a good Excel spreadsheet.
Remember I'm a Wannabe Solar Guy.

Cariboocoot

Re: Newbie - Wannabe Solar Guy

Well ... a Watt hour is an Amp hour times the Voltage. So if you have the need for 456 Watt hours from a 12 Volt battery system the batteries have to have a capacity of 456/12 = 38 Amp hours.

Since you only want to discharge the battery 25%, the total battery capacity becomes (38 Amp hours * 4) 152 Amp hours @ 12 Volts.