New to Solar and a lot of noobie questions :)

ehazell94

First off I would like to say hello to everyone I am new to the site and new to using/trying to use solar power. My name is edward and I am from Northern NJ, I was hoping everyone would be able to advise and or help with my first solar setup.

My living situation currently is a 1 bedroom apartment :
Power Usage = average usage 700 Watts

The setup I have designed so far is:

- All Black 100W 12V Solar Panel
- 75AH 12V DC Deep Cycle Solar Energy Storage Battery
- Attwood Powerguard 27 Battery Box Vented
- LCD Digital Voltage Panel Meter Voltmeter 7.5V -> 20V (Would install on/off switch)
- Whistler Pro-2000W Power Inverter

My basic concerns since I have never done this before and am new to the whole electricity field;

1.) Should there be any types of Diodes, or like safety mechanisms between these items? What would you add to ensure safety/efficiency? Don't want to over charge the battery or damage the panels/battery/inverter in anyway if possible.

2.) What type of wires would you use for the connections for a setup like this? What type of wiring would be best?

3.) When using an inverter does it add to the Amps being drawn from the battery? Say I was running enough appliances to pull about 16 Amps per hour, how much would that inverter add to the equation like would it be plus 1 - 2 Amps making it a total draw of 17 - 18?

4.) If I was to use a heating element appliance that draws near 1800 watts would any type of like breaker be needed? again just trying to be safe and keep my system safe.

5.) Any other knowledge or input is greatly appreciated, again this is my first project and first time working with solar panels, and I would like to ensure I am doing things correctly

THANKS SO MUCH FOR ANY AND ALL INPUT
and in advance it is nice to meet all of you!!

jcheil

Re: New to Solar and a lot of noobie questions

Some things that the experts here will likely need to know first:

You say your average usage is 700watts. You need to be more specific and measure it in watt-hours.
That number of 700 doesn't seem to make sense unless you are saying you consume 700wh per day which seems really low for an apartment that has a refrigerator that likely uses almost that amount itself.

Lastly, you need to let us know what your end goal is. Are you going to be trying to run everything from the solar? And if so, how? Will you be allowed to install panels on the property/structure?

The current equipment you have is basically "hobby/learning level". You would be able to run a few lights here and there but not much else. And forget running an 1800 watt heating element. Even though it is a resistive load and will not surge, and even if your inverter is truly a 2000 (and not a surge 2000), your battery would only last a few minutes.

NorthGuy

Re: New to Solar and a lot of noobie questions

There's a clear discrepancy here.

700W average is 0.7x24 = 16.8WH/day. This would require a solar array around 10kW (give or take).

ehazell94

Re: New to Solar and a lot of noobie questions

Good Afternoon,
My main goal with this situation is I am trying to be able to run multiple appliances in the case of a power outtage. My living room appliances draw a total of 700 Watts, I was hoping to be able to run the appliances for a certain amount of time to be able to rely on solar energy.

I wanted the situation to either be running living room appliances for a certain amount of time, or just running the conventional oven to still be able to cook food.

I had the idea last winter when we had lost power for about 5 days, so I was hoping to have a system that could.

700 Watts running for about --> 4 - 8 hours
1800 Watts running for about --> 1 - 2 hours

I looked at my electricity bill for the highest and lowest points it returned as;

Winter: 304 KWH about an average of 10.2 KWH per day
Summer: 646 KWH about an average of 22 KWH per day


What type of system would allow me to achieve that? or at least being able to run the living room appliances 700watts for an extended time of 4 -> 8 hours?

THANKS for any help in advance and I really appreciated how much you guys are actually explaining this to me!

NorthGuy

Re: New to Solar and a lot of noobie questions

To run 700W for 8 hours you need 5600WH. Assume you want it to be stored in batteries. Most batteries can only be discharged to 50%, so you need 11200WH of battery capacity. One golf cart battery is about 1300WH capacity, so you'll need 8 golf cart batteries. You can charge these from the grid and then if it's an outage, you have 8 hours of power.

If you want to charge them with solar, assuming you configured them for 24V, you will need at least 40A to somehow charge them. This is barely enough. To get 40A, you will need 1000W of solar panels. On a good sunny day these panels will almost re-charge the batteries.

Divide everything by 2 to get estimate for 700W for 4 hours.

An alternative is to buy a small gasoline generator, such as Honda 1000W inverter generator.

BB.

Re: New to Solar and a lot of noobie questions

Conservation will be your friend here... I will run through the numbers for a 700 watt load for 8 hours as if this was an off grid cabin. Nothing written in stone, just so you see how this all snowballs into a "wallet emptying event".

First, you average power requirements:

• 700 watts * 8 hours = 5,600 Watt*Hours per day (5.6 kWH per day)

A flooded cell battery bank with 1-3 days of storage and 50% maximum discharge (for longer battery life)--Pick 2 days:

• 5,600 WH * 1/0.85 inverter eff * 2 days of storage * 1/0.50 max discharge * 1/48 volt battery bank = 549 AH @ 48 volt battery bank

Two ways to calculate solar power array... 1) is based on size of battery bank; and 2) is based on hours of sun per day.

1) Recommend for solar power around 5% to 13% charging current for battery bank:

• 549 AH * 59 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 2,103 Watt array minimum
• 549 AH * 59 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 4,207 Watt array nominal
• 549 AH * 59 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 5,469 Watt array "cost effective maximum"

2) Hours of sun per day to replace the power you used.... Using PV Watts to estimate the hours of sun per day, fixed array, tilted to latitude in Newark NJ:

Month    Solar Radiation (kWh/m 2/day)
1      3.36     
2      4.05     
3      4.58     
4      4.84     
5      5.30     
6      5.33     
7      5.27     
8      5.25     
9      5.06     
10      4.46     
11      3.15     
12      2.87     
Year      4.46      

Toss out the bottom three months, and February at 4.05 hours of sun per day will be your "break even" month (may or may not need backup power/generator):

• 5,600 Watt*Hours per day * 1/0.52 end to end system efficiency * 1/4.05 hours of sun per day = 2,659 Watt Array minimum

So, based on my guesswork and off grid power model, you would need around 2,659 watt to 5,469 Watt array to power your loads without a genset (on average) for ~9 months a year.... And a 4,207 watt array would be a nice healthy off grid system.

With a 4,207 watt array and 5,600 WH load, the hours of sun you would need to "break even" would be:

• 5,600 WH * 1/0.52 system efficiency * 1/4,207 Watt array = 2.7 hours of sun minimum per day....

That size of array would power such a load pretty much all year long except for during stormy weather (2 or more days of poor sun).

This is not a "small system". And probably not a "cost effective" backup system for most people.

Otherwise, you can purchase a Honda eu2000i for ~$1,000 and run 700 watts for 8 hours on less than 2 gallons of gasoline per day.

I have a 3,500 watt Grid Tied system--And no matter how I cut it--A backup genset and 20+ gallons of stored fuel (~10 days of no utility power) still looks like a better solution for me for emergency backup power.

Plus the generator and fuel are both "portable"--The 549 AH @ 48 volt battery bank is about the equivalent of 20 "golf cart" sized batteries (20 batteries * 67 lbs each = 1,340 lbs)... Not exactly portable when compared with a 50 lb genset and a 120 lbs of fuel (plus gas can weight).

It all depends on your needs.

-Bill