What's Better For Time Of Use Rate Plan: West Facing, Oversize, or Battery Storage?

[Nifty]

I already have a 3kw system facing south, but it is no longer enough to cover our usage. I'm kicking myself for not sizing it larger 10 years ago when I got solar installed.

I'm in California on a Time Of Use rate plan where electricity is much more expensive during peak usage times from 4pm - 9pm (when solar isn't producing as much... i.e., the duck curve of solar & consumption).

I'm debating what will produce the overall long-term bang for my buck. There are a handful of options / configurations. A few things I'm considering:

• Over-build my system and send excess power back to PG&E at a lower rate
• Have my panels facing West. Even though less efficient, they will produce more power during the evening than the South facing
• Battery backup to grab excess during the peak times and use it in the evening

I haven't run the numbers yet, but my gut is saying it might be best to add a new system facing West and oversize it considerably. It seems that this would be cheaper and easier than a big battery backup system and would break-even much sooner. (basically, swapping out the price of a large battery backup in exchange for a bunch of extra panels facing West).

What do you think?

... basically the idea is similar to what they found in research here:

Overbuilding solar cheaper than seasonal storage and natural gas in Minnesota

An analysis by Clean Power Research, commissioned by the MN Solar Pathways Initiative, shows that 10% solar by 2025, and 70% wind+solar+storage in 2050 can be achieved at a comparable cost to natural gas-fired generation.

pv-magazine-usa.com

 

[flowerbug]

have you already done the other upgrades to the house to reduce energy use? better lighting, insulation, refridgerator, etc.?

how are you getting your hot water? to me that is always what i would do after the above. when putting in the solar hot water system i would have them put in the solar panels to run the pumps and the inverter and everything including a grid tie in so that in the future i could add more panels to the system so it ends up being two systems that share a lot of the same costs.

battery storage, last, since these days it may end up coming along with an electric car instead of having to have a separate unit though with grid tied house and a reliable power company i don't really think it makes much sense to have much battery storage. i only want a few minutes worth so i can shut down the computer and run a light if i need one.

 

[Nifty]

Great thoughts / ideas!

have you already done the other upgrades to the house to reduce energy use? better lighting, insulation, refridgerator, etc.?

For the most part, yest. I'm in a pretty mild climate and don't use AC. All lights are CFL or LED. Fridge is pretty efficient.

how are you getting your hot water?

Gas, and that's relatively cheap out here. Most of my $$ is going to electricity.

so that in the future i could add more panels to the system

Yeah, I wish I had thought of having flexibility built-into the system I had built before. For a handful of reasons I can't expand it, and would have to do a new system... which is why I'm thinking about having a new one facing west.

battery storage, last, since these days it may end up coming along with an electric car instead of having to have a separate unit

EXACTLY! I think Nissan is working on this. I don't see why they aren't building bi-directional systems into all electric cars. They sit there for hours and could be used for lots of things... emergencies at a minimum!

 

[flowerbug]

...
Yeah, I wish I had thought of having flexibility built-into the system I had built before. For a handful of reasons I can't expand it, and would have to do a new system... which is why I'm thinking about having a new one facing west.

EXACTLY! I think Nissan is working on this. I don't see why they aren't building bi-directional systems into all electric cars. They sit there for hours and could be used for lots of things... emergencies at a minimum!

oh, too bad about not being able to expand your existing setup easily. :/ facing west will give you a little expansion of the time but in terms of juice generated i'm not sure it is worth it. active tracking may have made some progress in 10yrs so maybe check that out as then you get the gains in both morning and evening. i've not really followed the technology the past several years since there is little chance i can do anything here.

and yes for the battery storage option being in the car (a part or in the whole). i know this is coming along but is not yet the norm, in Australia they were adding solar to houses and using the batteries as a power source for the grid if needed. with the goal of getting 50,000 houses installed. i think they're just now getting to 1,000 or so. i don't know if it is integrated with an electric car or not.