powerwall2 behavior when paired with solar

[Ampster]

I don't support overselling anything either, but how do you propose preventing sales people from over selling anything. If they lie and that lie causes damage they should be liable for the damage.

[solardreamer]

Why would a battery vendor say anything else? Why would a Generator vendor suggest anything else than their product? I see three options available to people with solar.
Battery
Generator
Battery and Generator.
Generac has purchased a battery vendor. While there is no integrated product offering yet, Coupled with a generator, a hybrid inverter with battery could leverage solar for load shifting and when power is out. That combination could provide longer time when the grid is down and the skies are cloudy without the expense of more Lithium batteries. . While I am not a fan of using a generator the above combination could be cost effective. The new Fire Code limits the size of battery installations and that might also create a larger market for the above combination.

Because that's the right thing to do? More importantly, there could be serious consequences for people that have critical medical needs (e.g. CPAP machines, medication that go bad without refrigeration, etc.) or disability needs (e.g. stair lift, etc.). So, you and some others may have backup power needs that could be fully addressed by home battery but that is not true in general. I am actually excited about all the battery technology development but I do not support overselling it. Toyota oversold the efficiency of hybrid engine technology in Prius and eventually lost major lawsuit for misleading consumers. I can see similar situation eventually happen to home battery vendors that market home battery as replacement for generators in general for backup power needs even if they have explicit disclaimers in fine print.

[Ampster]

Judging by the last few posts I still see a battery for backup power mindset. I have friends being told by home battery vendors that they don't anything else for backup power which I believe is very misleading. For backup power usage (i.e. not load shifting/grid avoidance), I would like home battery vendors to be more honest and tell consumers they still need a generator for reliable on-demand backup power and home battery is a nice add-on for additional convenience (e.g. emissions, noise, etc.). So, it should be a generator vs generator+home battery consideration for the consumers.

Why would a battery vendor say anything else? Why would a Generator vendor suggest anything else than their product? I see three options available to people with solar.
Battery
Generator
Battery and Generator.
Generac has purchased a battery vendor. While there is no integrated product offering yet, Coupled with a generator, a hybrid inverter with battery could leverage solar for load shifting and when power is out. That combination could provide longer time when the grid is down and the skies are cloudy without the expense of more Lithium batteries. . While I am not a fan of using a generator the above combination could be cost effective. The new Fire Code limits the size of battery installations and that might also create a larger market for the above combination.

[Ampster]

Sort of like the idea that a camel is a horse designed by committee ?

Not at all like that. The only similarity between collaboration and committees is that they both begin with the letter "c".
Design build contracts are an example as are any engineering projects that involve more than one discipline. An offshore oil platform comes to mind. No doubt it takes a leader with project management skills since the design process is a project by itself.

[RichardCullip]

Sort of like the idea that a camel is a horse designed by committee ?

When I was still working and if a meeting was seen as a necessary evil, I usually tried to hold it in a room with no chairs. Not popular, but the meetings were a lot more productive, shorter and a lot less frequent. My bosses usually thought I was a prick, but they were also engineers and usually left me alone.

Collaboration too, has limits. Someone must lead and channel it.

When I was working in the oil industry up in Bakersfield, we had plenty of meetings. They grew more numerous towards the end of my career. Quite often I had the thought that "None of us is as dumb as all of us" running thru my head whenever we struggled to reach consensus.

[scrambler]

So, it should be a generator vs generator+home battery consideration for the consumers.

I agree people should be made clearly aware of all the pros and cons of the various solutions.
That said, the final choice depends on every customer needs, circumstances and preferences.

In my case nothing is Critical to the point that I would even consider a generator. I used to have a generator and I have lived with two electric cars for 6 years now, and I would definitely prefer a Lithium Battery backup solution (combined with solar).
Battery backup would offers me all I need with much more comfort.
But yes, it will cost me extra for that comfort

[J.P.M.]

I think in many cases the final decision is often optimum when reached in a collaborative process.

Sort of like the idea that a camel is a horse designed by committee ?

When I was still working and if a meeting was seen as a necessary evil, I usually tried to hold it in a room with no chairs. Not popular, but the meetings were a lot more productive, shorter and a lot less frequent. My bosses usually thought I was a prick, but they were also engineers and usually left me alone.

Collaboration too, has limits. Someone must lead and channel it.

[solardreamer]

Judging by the last few posts I still see a battery for backup power mindset. I have friends being told by home battery vendors that they don't anything else for backup power which I believe is very misleading. For backup power usage (i.e. not load shifting/grid avoidance), I would like home battery vendors to be more honest and tell consumers they still need a generator for reliable on-demand backup power and home battery is a nice add-on for additional convenience (e.g. emissions, noise, etc.). So, it should be a generator vs generator+home battery consideration for the consumers.

[scrambler]

I respect your viewpoint and share the idea that over analysis can lead to confusion.
But that's not what I often see around here and elsewhere.
What I often see looks to me like red herring criticism of ideas that take more than one sentence to explain from folks that have short attention spans and lack critical thinking skills.
One of the consequences of the great dumbing of America.
There's a lot of middle ground between simplistic answers that don't explain anything and endless analysis for its own sake.
Rant mode off.

+10

[J.P.M.]

Sometimes on this forum I see paralysis of decision making by too much analysis. I thought I would offer another viewpoint. That is the benefit of forums like this.

I respect your viewpoint and share the idea that over analysis can lead to confusion.
But that's not what I often see around here and elsewhere.
What I often see looks to me like red herring criticism of ideas that take more than one sentence to explain from folks that have short attention spans and lack critical thinking skills.
One of the consequences of the great dumbing of America.
There's a lot of middle ground between simplistic answers that don't explain anything and endless analysis for its own sake.
Rant mode off.

[Ampster]

Brainstorming is good, but then a solution must be chosen.

I have enjoyed the brainstorming processes you have shared. Architects sometmes refer to a design Charette as a similar brainstorming process. I think in many cases the final decision is often optimum when reached in a collaborative process.

[bcroe]

Brainstorming is good, but then a solution must be chosen.

I look for elegant solutions. That is one that has no negatives compared to the earlier
design. Like disc brakes. A lot of stuff here did not reach elegant status until until a
very long design consideration process. Am so glad I did not rush to a quick fix.

I see a huge amount of un elegant stuff these days. Bandaid a quick fix together, ever
adding complexity and negatives to the solution. Bruce Roe

[Ampster]

Don't know why you'd think that.
...

Sometimes on this forum I see paralysis of decision making by too much analysis. I thought I would offer another viewpoint. That is the benefit of forums like this.

[J.P.M.]

That reminds me of the saying, "Don't let perfect be the enemy of good." I have no problem using assumptions for modeling. No doubt it is important to test the assumptions along the way and sometimes they don't turn out to be exactly as predicted. Indecision is actually a decision to do nothing.

Don't know why you'd think that. Perfection is an unattainable goal. Modeling may get you a less imperfect design if done well. Perfection is the goal of a fool. Constant improvement is attainable.

It's good you have no problem with assumptions because aside from death and taxes, everything about the future and particularly when dealing with engineering models including solar modeling and the economic analysis that is usually not done in any serious way is all based on assumptions of future conditions. No way to avoid assumptions.

The trick is to know which assumptions may be a better fit with reality as it unfolds. I've found some experience and a lot of luck seem to help.

On indecision: Indecision is the inability, for whatever reason(s), to make a decision. It implies awareness of a condition but the inability to decide what to do about it. Doing nothing is often the result. That's a passive action.

A conscious, reasoned decision to do nothing is indeed a positive action and may be a viable choice depending on the opinions and conclusions of the decision maker.

The two are not the same.

And, of course, hypothesis (assumption) testing is important. But starting with realistic assumptions that reflect reality and the real world, and knowing why those choices may be more realistic than other assumptions saves a lot of waste at the front end of the design process.

Choose to act, educate, design, implement, observe, modify, iterate.

Take what you want of the above. Scrap the rest.

[Ampster]

Part of the problem is and always will be getting and using assumptions about future conditions and things like utility rates, inflation, alternate investments, etc., as well as how long to make the analysis run.

That reminds me of the saying, "Don't let perfect be the enemy of good." I have no problem using assumptions for modeling. No doubt it is important to test the assumptions along the way and sometimes they don't turn out to be exactly as predicted. Indecision is actually a decision to do nothing.

It seems to me that at this time, batteries aren't cost effective for most users as a means to avoid peak rates.
.

Probably correct for the majority of people out there. It is clearly a niche market at this time. As a tool to leverage solar by load shifting batteries are more than just a means to avoid peak rates. With big differentials between peak and off peak there are also arbitrage opportunities.