Potential build question, whole home, bad net metering

[ebreard]

Hello,

I recently joined after lurking for a while. I have been trying to thing about a feasible solar system to offset or eliminate my electricity costs. I am in North Louisiana the utility company is entergy. I was hoping to do a grid-tie system but have had a hard time deciphering entergys net metering policy. I called for clarification but all I have heard is they would get back with me which won't happen.

before 2020 it was all retail. Since then:

"During each billing month, customers will pay the applicable retail rate for all electricity (in kWh) purchased from the utility and will receive the full retail value for all electricity that they produce and use behind the meter at their home or business. Any surplus energy not used by the customer and sent back to the grid will be credited on the customer's bill at the current Avoided Cost rate of approximately $0.0368 beginning April 1, 2022."

The way I read that is if I pay my full bill at .015 per kwh and they credit me my production at .0368 per kwh. which seems like garbage. Thanks Louisiana Public Service Commission.

So, I have began to look at some sort of hybrid system. I use on average about 2800 kwh/ month. In July it was 4000 kwh, wife at home most of the month with AC on and it was 100 degrees. 4500 sq ft house, spray foam insulated 5.5" thick. Geothermal heat pump AC

To make it more interesting I have underground service coming to my house and to a barn. The underground line passes my barn where a transformer is spliced in (above ground in junction box) then continues another 1000 feet or so to my house to a second transformer. My house has a standby propane generator with auto transfer switch.

My first question is where would I even be able to tie into my house or barn? Do I need two tie points and have to run wire to each? To get on the downstream side of the meters? I would like to put a standalone solar array within a couple hundred feet of my barn but I use all the power in my house.

I was thinking 20 kw of panels to support 100 kwh average of daily use w/ 5 hours of generation time. Then I would need batteries to hold all of that energy. 20 lipo4 batteries.

Could this be arranged to where i just discharge the batteries from 7 am to 9 pm or something like that during peak usage?

Just trying to come up with the most advantageous approach. I am not necessarily trying to go off grid as I live about a mile from the power plant but, the energy rates are getting ridiculous. Not really scared of overall cost as long as payback can be realized.

Thanks for any advice,

Ricker

 

[Solar Guppy]

Just trying to come up with the most advantageous approach. I am not necessarily trying to go off grid as I live about a mile from the power plant but, the energy rates are getting ridiculous. Not really scared of overall cost as long as payback can be realized.

At your utilities rates, the payback would be never. The cost for a storage system of 100 kwh is far more than 15 cents a kilowatt and then you get into how long before parts need to be replaced, code issues as that is far greater than current codes allow for residential energy storage. The general rule of thumb is $1 kwh for a storage system, while expensive, to those in off-grid homes it is just the cost of not having neighbors.

 

[Mattb4]

Except for when the government mandates and gives the electrical company incentives to allow net metering I doubt that many would want to. They certainly do not want to give an individual the same cost for electricity sold to them as retail cost. They buy electricity at wholesale and maintain very expensive equipment and people to distribute and keep it running. By selling to a large group of customers they get the benefit of scale. They only cover costs and profit by charging customers more than wholesale. Plus there is the whole solar instability issue that crops up based on the variable nature of solar the grid sees.

By and large without a subsidy an individual will not beat a utility companies cost structure for delivered KWH. Every time I read about someone wanting to reduce their electric bill by going solar it makes me wonder if they added up all the costs.

 

[Ampster]

A lot depends on the cycle for that calculation. In other words is the Net calculated every 15 minutes or once a month?
That is critical for designing a system. If it is monthly, then you might be able to use the grid as a battery overnight and save on purchasing a bigger battery. If every 15 minutes then you would need a bigger battery to store daytime energy for use at night. Solar can be competitive with $0.15 per kWh utility power but my calculations suggest it is hard to get the cost below $0.20 per kWh for DIY storage. More details and a clearer understanding would be needed in order to make an informed decision.

 

[ncsolarelectric]

I can help you. Your utility rates are similar to what I have here in NC from Energy United Members Coop. For any energy my system exports to the grid, I get credited at the Avoided Cost Rate of $0.04636/kWh. Anything I use which doesn't come from the grid, offsets my cost at $0.0767/kWh. So it's the same thing. Anything you produce and use on-site offsets reduces your bill by $0.15/kWh.

I have designed an extremely low-cost, DIY grid-tied system with battery storage using microinverters. A link to the 1-line diagram is in my signature and on this site's Resources page.

I just drew this up today, first draft.


Update 8/28/22: This didn't work as shown. Each DC input to the inverter requires a minimum 0.2 Ohm resistor, in series with the 15A, DC fuse. Once the resistor is added, the current is well within the range of the inverter. I'm running it right now. The resistor on a heatsink is 61C without a fan, at 24C ambient. Beautiful! Next item is the charge controller and a couple of panels to charge the battery. If I had just purchased a 48V, UL Listed battery, everything would be UL Listed and I think it would pass inspection as an energy storage system, not a stand-alone backup system.

 

[ebreard]

Ampster,

It is calculated every 15 minutes.

ncsolar,

your rates seem a little better. Mine are .11 - .12 cents apart. It seems like I would be better off trying to hold on to whatever power I could.


Thanks for all of the responses so far, most of my power usage is in the summer either during daylight hours (weekends mostly) or from about 5 - 9 pm to cool the house. Again, I am not really trying to go off grid but was wondering if it would be possible to discharge battery storage from 7- 9 (or whenever solar array is producing) then use solar power, then discharge batteries from 4 pm - 10 pm. Something like that. Most AC cycling is going on during the day until about 10 pm. That would be a much smaller bank than 100 kwh, probably half?

would I have to tie into system in two places? Downstream of each meter.

thanks again for the suggestions.

 

[Solar Guppy]

Thanks for all of the responses so far, most of my power usage is in the summer either during daylight hours (weekends mostly) or from about 5 - 9 pm to cool the house. Again, I am not really trying to go off grid but was wondering if it would be possible to discharge battery storage from 7- 9 (or whenever solar array is producing) then use solar power, then discharge batteries from 4 pm - 10 pm. Something like that. Most AC cycling is going on during the day until about 10 pm. That would be a much smaller bank than 100 kwh, probably half?

Doesn't matter size of system, pay back is never. Your utility costs are significantly less than storage costs, which would only offset your 15 cents a kwh.

Storage offset is used for TOU ( Time-of-use ) locations, where it can cost triple your rate in peak usage windows AND the utility is doing net-meter so when one sells to the utility from the battery, the home-owner is getting the 3X rate as a credit.

 

[Ampster]

Your utility rates are similar to what I have here in NC from Energy United Members Coop. For any energy my system exports to the grid, I get credited at the Avoided Cost Rate of $0.04636/kWh. Anything I use which doesn't come from the grid, offsets my cost at $0.0767/kWh. So it's the same thing. Anything you produce and use on-site offsets reduces your bill by $0.15/kWh

I agree that whatever he produces and uses on site reduces the OPs bill by $0.15. As he pointed out his differential is $0.11-12 per kWh and yours is $0.03 (0.076-0.46). That may lead to a different conclusion than your situation. The other question is whether those are all in rates or just generation? Is distribution charged on a different basis?
I agree with @Solar Guppy , that storage has a better payback when the differentials are greater as in a TOU rate environment. If that is a possibility then storage may be a hedge as well as providing backup.

 

[Ampster]

Again, I am not really trying to go off grid but was wondering if it would be possible to discharge battery storage from 7- 9 (or whenever solar array is producing) then use solar power, then discharge batteries from 4 pm - 10 pm. Something like that. Most AC cycling is going on during the day until about 10 pm. That would be a much smaller bank than 100 kwh, probably half?

would I have to tie into system in two places? Downstream of each meter.

I am doing that but my summer rates are peak at $0.55 and off peak at $0.23. My True Up is once a year so I can put kWhs in the bank at $0.55 per kWh, avoid that cost by using battery power during that high rate period and use some of those stored kWhs during winter to offset winter rates of $0.35 per kWh.

 

[ebreard]

Wow, thats high. 2 years ago our rates were .09/ kwh. I think .15 is robbery can't imagine .55.

everything is charged per kwh of usage. It is not broken into transmission/ generation. With just doing grid tie and panels I would only be able to take advantage of the .015 kwh offset for those hours (not sure what those hours are 9-3?) which doesn't include any of my peak usage. would probably save ~$110 month (during summer anyway) and maybe make $5/ month selling back to utility so, less than $1000 per year it looks like.

 

[Jaxonwood]

Hello,


Thanks for any advice,

Ricker

Ricker, it appears you have net metering that gives you an even-Steven swap for kWh up to your usage - with a terrible price received for any surplus you generate. Here in Communifornia, this surplus or shortfall is calculated once each year for a "true up" billing or credit.

The equal horse trading is a great thing to get yourself grandfathered into as a wave of changes starting over here sweeps the country. The best sized system will produce exactly what you consume as you will be able to use the grid as free storage.

Find out the details about the current program - period for accounting the power trading with the grid.
Find out what grandfathering exists for new users into this scheme, here it is 15 or 20 years.

A $.15/kWh rate isn't bad, it won't get better, it almost certainly will be going up in months ahead. (Here: $.32-$.49/kWh)
The big three utilities here are trying to end this trading scheme for a new and much more detrimental scheme for the customer. Getting grandfathered in here is critical. I expect it will become so for you too ahead.

 

[jpimlott]

Yeah i read about net metering 3.0 in California and is was all bad.
It would have killed the solar industry outright.
They did a similar thing in Nevada and killed solar there.
I have since decided to go a far off grid as possible with a hybrid system.
Off grid inverters with diy batteries and transfer switch for bad days or testing maintenance.

 

[wheisenburg]

If every 15 minutes then you would need a bigger battery to store daytime energy for use at night. Solar can be competitive with $0.15 per kWh utility power but my calculations suggest it is hard to get the cost below $0.20 per kWh for DIY storage. More details and a clearer understanding would be needed in order to make an informed decision.

It looks like this is instantaneous. If you use the power you produce on your side of the meter you don't pay for it. Once you export the power outside the meter, they pay you 3 cents. It cost 15 cents to buy it back.