New to Solar

System · May 2008

First off! Hello All!

Thanks for having me, bust most of all thank you for this website!

I don’t know where to start, I’ve read numerous websites but it seems all is scattered or limited information and piecing it together can be a challenge for the unknowledgeable nerd like me.

My current household usage is 620 kWh monthly.
This house is a two story 2400 s.f. home; I have double pane windows throughout and double insulated walls (Foam and Insulation).

I live in Goodyear Arizona and I am in a perfect location for almost 8 to 10 hours of sun daily (guestimate), I also have a solid flat patio cover in the backyard that can house about 4 panels maybe more.

I changed all bulbs to CFL ranging from 9 watts to 60 watts, I also changed my electricity habits by unplugging all items not being used on a consistent bases.

So here is what im trying to accomplish:

A Grid tied system, slowly upgrading as funds become available or buying in stages.

I know I may have to fork out some cash in the beginning but that’s okay.

Is it possible to buy a 180 watt solar panel, a charge controller, a few optima batteries a power inverter to start off with and then add panels as I can afford them, adding another controller and batteries as I see fit?

My goal is to just start some where and add, add, add, WITHOUT having to sell any items I already purchased in the future, kind of like buy the good stuff one at a time?

Please I KNOW nothing about how the system should be configured, the nice thing is I am willing to learn, and my brother in law is a certified electrician, I just need to do all the ordering, he's just going to come in and wire everything up and make sure it meets building code etc.

Any help would be greatly appreciated.

DaBear

mike95490 · May 2008

Re: New to Solar

Well, the good news is that asking for a grid-tied system, you won't need any batteries.

The bad news is, the grid tie inverters, need to have about 700 watts of modules (about 300Vdc worth) before they power themselves up. (the DC voltage has to be somewhat higher than the USA 240VAC split phase). I'm partial to the Xantrax GT series of grid-tie inverters, and you can get a 3 or 4 KW rated module, and add strings of 8-11 panels, one string at a time, as your budget allows, till you reach the inverters limit. then you can always add another inverter.

Depending on your electric Co. & local codes, you will ALWAYS have to get the first installation approved. Maybe as you add each additional string each year, you can forgo the extra inspections, as long as the final Mounting Rack for the panels, is approved the first time.
(wind & weight load on the house rafters).

This would not give you any standby power, but for the cost of batteries and extra fancy grid-tie & stand-alone inverter, you could buy a small generator to keep beverages cold.

BB. · May 2008

Re: New to Solar

Xantrex (and probably all of the other inverter/controller manufacturers) has a simplified diagram and explaination of the three major category of Solar PV systems...

1) Grid Tied--cheapest to install, cheapest power, least maintenance, most efficient, very few components.... #1 choice for best bang for the buck. If you are going to get rebates--this system will qualify (if rebates/credits are available for your area and depending and local RE subsidies which change over time).

Downsides, will only work when your utility power is up. No backup power at all, sun or no sun. Must get building permits and licensed electrician to install. And OK from utility company (smaller utilities and those outside the US will probably say no--at least at first). How much money you will save with the Grid Tie--does depend on the billing plan(s) that are offered by your utility company. 1-year net metering is best. Some pay back "retail" cost of power. Others wholesale cost of power. Some do the "banking" over a 1 year period. Others do it over 1 month.

You can add solar panels, up to the size of the grid tied inverter capacity. But, it is a pain because you have to start with a minimum size and may have to rewire all your panels every time you add new ones. So, at first you pay more than you need for the inverter, and then have to buy a few panels (typically of the same brand and model) as you ad one... Can be done, but for a 2x increase in power (doubling solar panels), you probably only saved 25% or so by populating the downsized system at first. May have an issue with re-inspections and discussions with utility company as you add panels/systems.

2) Off-Grid... Basically your remote home system. Usually installed when there is no (or very expensive to run) utility feed. Most expensive system to install (per watt*hour generated), and most expensive to maintain (battery replacements every ~5-10 years). Many people will start small projects with off-grid systems for their home (like emergency backup power for a fridge, or to run a home office).

Can be built by anyone--should follow code/good practices for safety. Can be built as a small system for learning all about solar.

Downsides... Where grid tie may cost you $0.25 per kWhr (really rough estimate), Off Grid will cost you well more than $1.00 per kWhr--excluding the emergency generator and fuel for when the sun isn't shining.

You can add solar panels, but you should not add new batteries to an old battery bank (few year old+ batteries). Typically, the new batteries will fail about the same time as the old batteries do (the new batteries "wear down" because they carry most of the charge/discharge cycles when new--and quickly age to the same "state" as the existing batteries).

3) Hybrid system... Is an off-grid system with a special inverter/transfer switch which can operate both off-grid and on grid. Expensive to install, more efficient and probably a bit cheaper to maintain--because, most of the time--it operates like a Grid Tied system--and the batteries are just sitting there for backup.

Probably the system that everyone dreams of--but pretty hard to justify unless you live in an area with frequent or long power outages.

You can go here and figure out how many panels you would need to purchase to offset XXXKWhrs per month/year for your location (pick site close to your location, with similar weather).

As an example, Grid Tied system, 620kWhrs/month * 12 = 7,440 kWhrs per year... Pick Phoenix. Use defaults, find that 4.5kWatts of solar panels will generate about 7,600 kWhrs per year (works well with 1 year net metering).

That system would cost you, very roughly, $40,000 (retail, no rebates included) to install. Doing it your self (usually need engineering signoff for the roof racks, licensed electrician, permits and utility OK).

If you did everything yourself and found very good prices for the parts--you may save 25%-50% doing it your self...

-Bill

New to Solar

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