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Re: Solar for grid tied AND backup - where to begin?

Fri Sep 29, 2017 7:48 am

Thanks for the reply, great info there. So do I understand correctly, you got the Pika inverter with backup capability, but you didn't buy the batteries yet? How much additional did the backup add-on capability cost?
Did you consider the Schneider Conext box?

Correct. The battery system that they created in partnership with Panasonic would have just about doubled my cost, its really really pricey right now but I fully anticipate that after a year or so it will come down. The good news is that it is eligible for the federal rebate to bring it down 30%, but it was still going to be ~$13k-$15k. Again, these could be wrong since it was just released in July and installs aren't even really starting to occur until now. The reason I think its a nice setup is not just the integration, but it is designed for full discharge cycles. I intend to use it on self-supply to capture my excess production during the day and use it at night.

Lots of articles in the press here about how you can't use solar during an outage. Many are written to convey a narrative it's the evil power company keeping control over the masses. No doubt a bunch of people read the headlines and take away confirmation they're better off not having gotten solar.

The biggest reason is that with a grid-tie there needs to be somewhere for the power to go. If the grid is down any excess production has no where to go OR on the flip side, without something load shedding you'd be facing constant brown-outs as production exceeds demand on your side. Adding a battery fills both these needs. Excess goes into battery and battery then supplies when demand exceeds solar production.

Now, what happens when battery is full and production exceeds demand? That I dont know...

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Re: Solar for grid tied AND backup - where to begin?

Fri Sep 29, 2017 12:35 pm

Beardedjeff wrote:The battery system that they created in partnership with Panasonic would have just about doubled my cost, its really really pricey right now but I fully anticipate that after a year or so it will come down.

Do you have the option with the Pika system to just use a few golf cart batteries in the meantime or does it only work with their battery? Keeping the fridge and a few lights going overnight seems doable.
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Re: Solar for grid tied AND backup - where to begin?

Fri Sep 29, 2017 7:00 pm

LTLFTcomposite wrote:With recent power outages here after Irma whole house generator flights of fancy have returned. I'm thinking instead of sinking a bunch of money into something with zero ROI for the next decade waiting for another outage that may not even happen it's time to start thinking seriously about solar.

So much of it still looks like it's targeted at the enthusiast and is pretty bewildering. I guess for a grid tie system the basic components are the panels, a racking system and the inverter. Adding backup capability adds complexity, more components, more cost,
I think we use about 1000 kwh per month average, obviously more in the summer than winter.

I lived this after Irma. We were four days without electricity. I have a 4.7kw PV with about 30kw battery backup. What is upsetting though is that the batteries are marginal at best, being purchased from Balqon (long story, they're out of business now, what more can be said). We had lights, ran two refrigerators, watched TV, ran the A/C in the daytime, had hot water (with the hybrid water heater) and used the dishwasher. We were getting about 15kw / day, as I had to limit at times because we actually couldn't use at the 4kw rate the PV was generating at. What was most upsetting to everybody was that the Internet was out for a week.

I designed the system myself, got the permit, picked out the components, put up the conduit. I had a roofer come and install the racks on the garage roof. When he started, I asked, "Don't you need to snap a chalk line?" He looked at me like I was some idiot from Pluto. He said he's been doing roofing for 20 years and didn't need any chalk line. So of course, in the end, it ended up being a snake across the garage roof, and I had to loosen everything and adjust to get things at least 95% straight and drag 21 panels up a ladder myself to install them. I knew the electrician, so I thought everything was covered there, until ... one day I looked and saw his license had expired, so I asked and he said, "Wow, I'll have to look into that." The guys at the electrical supply house kept saying, "Fire the electrician" every time I saw them, and finally when he said, "Wow, I haven't bent conduit in awhile" I knew I had no other choice. I got a great electrician to come in and finish everything off. It turned out that a second set of conduit had to be run, because the local inspectors would not accept conduit as a ground, it had to be a wire, even though according to what I read in the NEC the conduit was acceptable. I ended up running much thicker wire though, so it ended up fine.

If I was doing it again, I'd keep the panels ground mounted. I'd stick with PbA batteries, but get quality 2V cells from Rolls or someone similar. I have the Xantrex 6048 also, and it has been fine for many years.

You need to calculate the 30% tax credit, the incredibly cheap price for PV panels, and yes, the batteries are expensive but when you're able to live essentially off-grid without major problems it really helps. It generates every day the sun shines, and payback is expected to be about 13 years from when it was installed, which back then I got a $4/watt rebate from Florida.

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Re: Solar for grid tied AND backup - where to begin?

Fri Sep 29, 2017 8:30 pm

My limited understanding of the situation today (though perhaps the Tesla PW is different ??) is that the battery back-up systems are based on 48v. This just tacks on extra electronics and a good 15% extra system losses in addition to the requirements to island off the home PV from the grid and the more complicated electrical work.

I expect systems to improve A LOT in the next few years, so unless their is an immediate need like living off-grid, consider waiting.
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Re: Solar for grid tied AND backup - where to begin?

Sat Sep 30, 2017 1:41 pm

Beardedjeff wrote: Their battery setup is done with Panasonic and is super easy to integrate later, its literally 2 wires plus a sub-panel with your backed up loads. I hope to add it in a year or so to allow grid-down usage.
- The Pika setup is a simpler system. There is no additional auto-transformer for battery backup needed, the one box does it all
- Both the Pika and Seraphim panels are made in the USA. I personally talked with the guys at Pika and they were very helpful.

Check out my production here!

I was told that the Panasonic Battery will be ready for sale this December. I'm very interested in the system with the battery as an off-grid backup energy supply and also to minimize my energy bills using a "solar days/free nights" contract that is available to me. If I could integrate my Leaf's battery rather than the Panasonic, I'd sign up today for the Pika system.

Please keep us informed of your system operation.
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Re: Solar for grid tied AND backup - where to begin?

Mon Oct 02, 2017 9:25 am

As you said, its tough to make any kind of rational decision simply based on ROI for a backup system. However, my wife hates the smell and sound of a generator, so I invested several years ago in a DIY solar-based backup system. (I have a separate 7.6kW solar system on the garage, which is grid-tied only). The system on my house is about 2.4kW, with an Outback charge controller, which keeps 4 huge gas mat/pba marine batteries charged. I have a 120 VAC Outback inverter that backs up a sub panel with the freezer, refrigerator, TV, and a couple lights. I also have solar hot water, so we have hot showers when the power is out, which is a nice bonus. As beardedjeff said, don't forget the 30% Federal tax deduction. I'd love to replace this system with a Li-ion-based setup that would also interact with my grid-tied system on the garage, but I haven't found exactly what I want yet. There is a lot of new stuff coming on to the market though, so I am hopeful. I'd love to install a larger ground-mounted solar panel system for it, if my wife would only let me cut down the trees.
I have signed up for a Tesla Powerwall 2 for my guest house, where my parents live, and plan on installing about 3-4 kW of solar to keep it charged.
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