Load shedding option w/ battery backupa

[Wavelet8]

So, I have a 10kw solar system on my home in new england. I’m doing fairly well with breaking even between production and usage but the electric Chevy bolt EV is putting me over the edge during the winter months. National grid has raised there rates this past November by 62 %. This means my electric bill is going to increase by $100 a month at least. I wondering if I should take another look at battery backup systems, and add additional panels for load shedding purposes.
I am not looking to spend 15k. I’m just looking to add maybe another 10 panels or enough storage to shed some load at night so I do not have to pay for distribution charges during the winter. I currently have a open breaker slot on my enphase solar combiner box. Is it possible to integrate a small Outback battery system for load shedding?

I guess I would have the following questions:
1) since 100 % netmetering systems are limited to 10kw, if I add an additional separate battery backup system and use it for load shedding will this cause a problem with my net metering rate?
2) Depending on the year, I’m only short breaking even about $ 700 a year. This will increase to maybe $1000 with the increase. Can a small battery backup/ load center expense be justified?
3) my house is fairly newer energy efficient construction. So, masssave wouldn’t generate much savings.

in summary: A small 15 amp string seems the best thing but but would rather not deal with lead acid battery maintenance.

Any advise would be appreciated

[SunEagle]

So, I have a 10kw solar system on my home in new england. I’m doing fairly well with breaking even between production and usage but the electric Chevy bolt EV is putting me over the edge during the winter months. National grid has raised there rates this past November by 62 %. This means my electric bill is going to increase by $100 a month at least. I wondering if I should take another look at battery backup systems, and add additional panels for load shedding purposes.
I am not looking to spend 15k. I’m just looking to add maybe another 10 panels or enough storage to shed some load at night so I do not have to pay for distribution charges during the winter. I currently have a open breaker slot on my enphase solar combiner box. Is it possible to integrate a small Outback battery system for load shedding?

I guess I would have the following questions:
1) since 100 % netmetering systems are limited to 10kw, if I add an additional separate battery backup system and use it for load shedding will this cause a problem with my net metering rate?
2) Depending on the year, I’m only short breaking even about $ 700 a year. This will increase to maybe $1000 with the increase. Can a small battery backup/ load center expense be justified?
3) my house is fairly newer energy efficient construction. So, masssave wouldn’t generate much savings.

in summary: A small 15 amp string seems the best thing but but would rather not deal with lead acid battery maintenance.

Any advise would be appreciated

I have heard that unless you have a TOD rate going with a battery or adding panels may or may not solve your issue.

If the weather is bad and snowy, additional panels will not help and a battery system is usually hard to cost justify unless your rates are very high or you can use them during a high rate period to purchase power from the POCO.

As always I say do the math before you buy.

[Calsun]

The battery banks from Tesla start at $7,000 and so no chance for a payback. Rates are usually low at the time of day when solar is not being produced so the value of the energy from the battery bank is marginal. And the battery banks can catch fire and release toxic fumes in to the air so not something you want around your house.

A Tesla Megapack lithium power unit caught fire at the Moss Landing energy storage facility and it shut down Highway 1. The unit was outdoors so no workers died but it is not something you want attached to a wall of your house.

What may work is a wind turbine to generate power whenever the wind is blowing. Normally the ROI is twice as fast as with solar. Many excellent models of low noise vertical axis wind turbines. There may be a PACE program in your area to help with the cost.

Easy to find NOAA information on average wind speed in any given area.

[peakbagger]

Wow, the wind turbine stuff came out of left field. It is extremely rare to find anyplace with enough wind to make a small wind turbine viable. Even if there is enough wind, its pretty rare to find a small wind turbine that is going to survive and far rarer to find vertical wind turbines with any track record. In general with small wind, there are far more failures than successes. We long term renewable folks wish it wasnt true but with rare exceptions it is just a waste of money. If you have about 600K and a good site, its another story.

Battery chemistry is starting to shift to LFP instead of LNMC chemistry, even Tesla is using LFP on the new Megapacks. Lower power density but far less prone to self destruct.. As for battery economics, it really depends on your state and possibly your utility tariffs. The major utilities in Mass are pushing them big time and the state utility incentives generally pay for the battery in 5 years. The trade off is the utility gets to "borrow" some of your capacity during times that they may need it. Eversource in NH is different story as there is no incentive for battery's currently and the solar rate structure does not factor in load shifting. You need a Time of Day rate preferably with net metering and not sure Maine, NH or VT offers them.

Generally, the utility is concerned with peak export to the grid so the 10 KW capacity (if that is your local utilities limit as they vary) is based on the total inverter capacity. You can put out more than the limit but usually that means a real interconnection agreement and far worse benefits. You may be able review if you are overpaneled (more panel output than the inverter can handle) and possibly add a few panels. You can also add an active solar tracker and pick up about 30% more power for the same inverter capacity if you have the site (open field to the east south and west). The problem with either is the sun resource in winter is lousy so unless you got a good net metering program with the utility you end up with an oversized system for most of the year.

I do have a grandfathered Net metering plan in NH, I can bank as much power as I can in the summer and get it back in the winter for "free" so in my case I would probably max out the capacity of my inverters that are under paneled and consider optimizing array angles to produce more power in the summer. The inverter capacity is grandfathered, so I cannot add another inverter, but I can make the ones I have work harder.

[Wavelet8]

Ok, lots of things to discuss.

1st) wind power and hydro wouldn’t work in my situation. Small lot, no water, trees around. Not a good fit. Now, if I lived in a canyon out in Montana it would be a different story.

2nd) I wouldn’t due lead acid or lithium nickel Just LiFePo to prevent run away conditions. But, the price is part of the problem at $1500 for rack mounted type.

3rd) only Certain types of systems qualify for the rebates. The battery systems can only export to the grid to qualify. Most the systems are in the 15k-20k range. But they also have lots of capabilities that I like.

From researching, I like the Sol-ark and the Outback skybox.

Some other rules apply: if you add the battery to an existing solar system over a year later you lose out on the rebate as well. So, there is a time limit.

however, if you add a separate solar panel system that isn’t part of the original then you can get the rebate.

The max. 10KW system for full netmeteringthreshold is a concern if you install and export to the grid on a single large system. This is the reason for the specific inverters to qualify. The can limit the export value during times when the grid transformers cannot handle them. They can also add to the grid during high demand summer events from the batteries.

You have to understand that solar is stressing existing transmission transformer assemblies. Solar power can be stepped up by existing transformers but not anywhere near the transformers capacity due to excessive heating on the primary going in the wrong direction. You would need a special transformer designed to handle both directions. The usually intails larger gauge wire. Generally, they just increase the transformer size up but make the home owners pay for it if the were the last ones

To install solar when the system ran out of capacity. The transformer upgrade is expensive so most do not install solar unless they can justify it under some federal or state program.

but I’m getting off topic:

I like the features: island mode that doesn’t require the grid for the micro inverters to run. These systems can also allow a gas generator connection in case the loss of power event is expected to take weeks.

ultimately, I would do a dc coupled 10 solar panel system to a battery rack bank of 4-6 of 30kwh storage bank.

in order to qualify for rebate I would have to a 6-8kw inverter.

The power would be added from battery bank when I’m not producing 10 kw which is most of the time or when I loose power.