diy solar

diy solar

Beginner to the forum and to Solar power

MarkD

New Member
Joined
Oct 16, 2021
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I need advice, I'm moving to a Rural area and I'm worried that the existing power grid is not reliable so I would like to install a solar system with battery backup for emergencies and for helping out the everyday needs. I would like to be grid-tied and of course, have a battery backup. I need to figure out the size of my system but I'm guessing around 12kw is a good starting point. I need advice on every component but it seems like the batteries are a huge choice/decision. Any help would be appreciated, thanks.
 
Welcome to the forum. Most important to sizing your system would be doing an energy audit. Calculating the use you will require.
 
guessing around 12kw is a good starting point.
Don’t guess. :)

Basics can usually be run on WAY less than the average home’s mindless grid consumption in kW and: if money matters, a smaller backup system (depending on needs) can often pay its own way much faster per kW than the systems that keep things going as if you never lost the grid.

So the audit: what do you have to run, want to run, or can’t live without running?
 
If you are grid tied, what is your priority? What are you planning for? Do your rates change depending on time of day?
Are you planning on cycling your batteries every day, or only when there is no grid power?
 
My priority is backup, but I figured if I'm going to build a system might as well use it daily. As I said I'm new to solar, so I'm looking for suggestions. If it's easier to build a system as solely a backup I'll go in that direction. I only mentioned grid-tie to help with recouping the cost. I'm open to any and all suggestions.
 
I'm a beginner so DYODD, but perhaps this can help as a starting point.

The most important thing is to determine your daily average load and minimum/emergency loads. You can get a watt meter for 10-20usd and it will give you a precise read for instant and daily use, they are amazing. I would recommend ordering one today, so you can start figuring out what would be used during an emergency (ie. fridge, lightbulbs, coffee maker, stove/microwave). You can look at the appliance specs, but take that with a huge grain of salt. For your average load you could look at your power bill to get a ballpark figure, but I highly recommend a watt meter. Also determine your sun hours depending on your location (https://unboundsolar.com/solar-information/sun-hours-us-map) and determine a "budget" or financial goal.

AFTER you have your load quantities.

1.-You will need a hybrid inverter. ie. one that will accept input from panels and the grid. You will have to match this to your peak demand.
2.- Determine how many days you will want to cover without grid tied power in both emergency and average use, in sunny and overcast conditions. This should provide a good idea for sizing your system. Check your budget again. Having solar in a grid tied situation *MIGHT* reduce your monthly power bills, but it is a large long term investment, which may never give you a good ror and batteries are the most expensive part. A grid tied system without battery backup will not be useable during a blackout (ikr?) even if your panels are producing energy.

This example is a completely off grid system. I get 6 sunlight hours a day. I have a 1kw system on my roof. That means on a good day, i can produce up to 6kwh (about 5.5 usable) or enough to run my fridge and two freezers 24/7, do a load of laundry and use a laptop and lightbulbs at will and have some left over for whatever. I have a 12KW lithium power bank, which means if it rains for two days straight and I maintain my usual consumption i will run out of energy. Obviously I can cut down on some pull like lightbulbs/fans and washing machine, but the fridge and freezers require their standard energy requirement (this is why the watt meter is so useful). My emergency load is only about 1.5kw per day, so in theory my bank could almost last 10 days (and probably would with even a little sun being picked up by my panels).
I'd size it differently for a grid tied system, starting with the emergency load and how many days the energy company "usually" fails. My uncle is usually without power for 5-8 days every 3 or 4 years due to snow storms, so his battery system was sized for 8 days of emergency autonomy considering only a 30% sun incidence, because usually if its snowing, its not sunny. I don't remember what his usage was or the size of his battery bank. His average energy bill is usually under 20dls, the investment was going to take over 8 years to pay for itself, but... now he doesn't have to worry about the power lines, ever and can keep his house 60° "for free" during the summer.

I think the bottom line is just getting your priorities straight, solar isn't always the answer.
 
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