Grid tie system

punkinsrock

Hello all, I am a noob here and to solar and wind power as well. I am sure the question has been brought up before but with over 100 pages of posts I am just going to ask. If I do a grid tie system how do I save money on my electric bill? Does my meter run slower if I am supplying power to my grid? And what if I am able to supply more power than I use? I am currently deployed to the middle east and when I get home I want to start experimenting with solar energy. Thanks for looking, Jeff

bill von novak

Re: Grid tie system

punkinsrock wrote: »

Hello all, I am a noob here and to solar and wind power as well. I am sure the question has been brought up before but with over 100 pages of posts I am just going to ask. If I do a grid tie system how do I save money on my electric bill? Does my meter run slower if I am supplying power to my grid? And what if I am able to supply more power than I use? I am currently deployed to the middle east and when I get home I want to start experimenting with solar energy. Thanks for looking, Jeff

In places with net metering, every kilowatt-hour you generate is a kilowatt-hour you don't have to pay for. If you supply more power than you use it is "banked" against your bill. In our area there is one settle-up a year, where you pay for any net energy you used. Yes, your meter will run slower (or backwards) when you are generating.

Cariboocoot

Re: Grid tie system

Welcome to the forum Jeff.

A grid-tie system supplies power for your household loads from a PV array. It may reduce the amount of power you purchase from the utility, or eliminate it, or even sell surplus power back to the grid. It all depends on how much power you use, how large a system you install, and what the weather is like.

Basically it gives you a parallel (not alternate) source of power. And just as if you connect two batteries in parallel to supply a given load you will draw less from each. Unlike batteries, however, grid-tie system has the added advantage that if the load can be satisfied from the solar there is no draw from the utility and if there is even more power available than needed the utility is fed that extra.

BB.

Re: Grid tie system

Grid Tied solar economics also depends heavily on your local tariffs/rate plans and if GT solar is even "Legal".

I live near San Francisco and am a PG&E customer.

I installed GT solar on my home (about 3.5 kWatts of solar panels) and I have never had more than a ~$4.50 minimum charge for power in that time (in fact, we are reasonably energy efficient for our home and the present array is actually larger than we need at this time).

And, in California (in general), you have to use a residential Time of Use plan... For me, I pay $0.27 per kWH (roughly) for summer weekday afternoons (noon to 6pm). And I pay $0.09 per kWH for summer off peak. In winter, my peak power is around $0.12 per kWH).

However, we also have "tiered pricing"--The more power I use, the higher rates I pay (like buying 150 lbs of steak at Costco and paying 3x what the typical person buys 1 lb of meet at Safeway).... For us, we never go over the "base tier" (around 300 kWH per month)--So we don't have to pay the $0.56 per kWH for using >~1,000 kWH per month--And we do not have A/C or electric heat (natural gas home)... So our bills are pretty low anyway.

You need to look at the rate plan for solar (you may have several to choose from, but all of them probably are ToU vs "flat rate" pricing). And you have to see if they make economic sense for you. If your home (assuming not commercial--a whole 'nother kettle of fish) does not have high power usage during summer afternoons/evenings (no A/C, no electric stove/hot water), then GT solar can usually save you "real" money on your power bill.

However, if your local utility does not allow GT Solar, or has some other type of rate plan, GT solar may or may not make economic sense.

In the end--It is almost always a better investment in time and money to understand where your power costs are going (a kill-a-watt type meter, and/or whole house monitor is a great place to start) and conservation (lots of insulation, replacing old single pane windows, weather stripping, modern Energy Star appliances, turning off stuff not used, replacing a desktop computer with a laptop, new modern/efficient heat pump for A/C, heating, hot water, etc. can all help reduce your bill by upwards of 50% (if you have an older home and never looked seriously at conservation before).

There may be a time window on GT solar--GT Solar is becoming very popular because many state PUC tariffs really favor the GT solar customers with very generous pricing terms. And many utilities are starting to push back and figure out new tariffs and/or prohibitions on new solar connections. It is more politics than engineering/marketing at the state/utility levels.

In general, in a sunny area, you may see GT solar costing you ~$0.10 to $0.20 per kWH... If your average utility costs are over those prices, you can probably save money with GT solar (and conservation efforts).

-Bill

peakbagger

Re: Grid tie system

Thanks for your service

Do yourself a favor and ask lots of questions before spending a dime. Its real tempting to buy something first and then ask questions later. A lot of questions and planning will really save you money and frustration in the long run.

jebatty

Re: Grid tie system

Ditto on finding out what is permitted by law, the local utility and the terms applying to grid tie. In our area for residential and other small systems the utility buys from us at the same rate we buy from them, get a credit on our bill, and settle up once/year. Also ditto on conservation first. Our electric energy conservation efforts dropped our kwh usage substantially. Our general use is now down to about 10 kwh/day, not including supplemental space heating in the winter or the basement dehumidifier for a couple of months in the summer. And except for our wood stove in the living room, our house is 100% electric.