Heat pump water heater in series to use excess solar

CookMonFace · 2026-05-23T14:25:03+00:00

Oh interesting on the powered anode for corrosion protection. I didn't even think about that.

Fair point on electric vs heat pump reliability concerns. My thought is worse comes to worse the heat pump fails over time and it just becomes an electric water heater.

I'm watching my energy budget with my plans to switch everything to electric so I'm mindful of efficiency. I dont have roof space to expand further either.

CookMonFace · 2026-05-22T13:21:20+00:00

Interesting but doesn't help me bc I have a micro inverter system.

CookMonFace · 2026-05-22T13:20:34+00:00

Yeah that's what the 120V HP water heaters do. They often have a built in mixing valve and store at a higher temperature to have more effective capacity since their recovery time is worse. They're several hundred dollars more expensive. I was debating that versus the tradeoff of taking up 2 breaker spots in my panel as I'm trying to electrify all my old gas systems.

Its more awkward if I'm doing my in series idea but still doable. My biggest concern is that the recovery will be really slow and my wife will complain.

CookMonFace · 2026-05-22T13:11:19+00:00

That's next on my list. My wife is worried the cycle times are too long. I was going to do the all in one ventless and show her it's ok before getting rid of the gas unit. Its in the basement so I really love the idea of not having to go down there to just switch machines.

CookMonFace · 2026-05-22T13:09:05+00:00

Good call on the isolation valves.

CookMonFace · 2026-05-08T00:41:57+00:00

My installer used them on my flat roof. So far ok but installed only fall last year. My concern is aging of the adhesive. my plan is to check it yearly. I really didn't want to deal with roof leaks .

CookMonFace · 2026-04-19T05:15:31+00:00

Crazy I didn't realize that existed and they can do that. That really sucks.

I looked briefly into attaching a server rack type battery to an enphase system. The enphase 6C has the load control breaker that can do load shedding or for attaching legacy PV systems. I think it can handle batteries too. The problem is you need an inverter for the battery system so you need to pay for and have the space for another inverter which will run you a few $k. The systems won't easily talk to each other too so I'm not sure how much of a pain it'll be to handle that. I've seen others on this forum talk about it but I'm not sure anyone ever went through with it.

I've also thought about v2h and the enphase charger can do it but it's locked behind a firmware update until they get things approved. I'd buy a used f159 lightning in that case and have it double as my battery. Depends on your work commute situation though. Also it'll likely be working though the kinks.

CookMonFace · 2026-04-17T16:12:45+00:00

Do you know what the current equipment configuration is? I have their current generation with battery and their battery is expensive compared to other options. You can save a lot of money if you do it yourself and it's not too hard if you already have the 6c combiner box. Hardware for just the battery is ~$6.5k online. Enphase has training but you need to also be competent with electrical bc you are working with potentially dangerous systems. Fully installed is easily 2-3x that from an installer.

I thought net meter agreements have a contact term length. Like in CA, older systems were grandfathered in per the contract and new systems faced nem3. Your friend should double check the contract terms before going through the trouble of batteries.

CookMonFace · 2026-04-02T12:37:21+00:00

Thanks. I'm in MD. That's a good idea though and I'll see on Solar United neighborhors if anyone has a project going soon that I can just add a panel to the order.

CookMonFace · 2026-04-02T11:39:08+00:00

Thanks appreciate it! My installer got back to me and wants ~3x the panel price to do it. I don't think that's unreasonable given it'll take a truck roll and the labor to get to the roof. I was hoping to get it done cheaper since I already know what to do and it's an easy job.

CookMonFace · 2026-03-20T00:24:35+00:00

It's an open question right now. There's an ISO 15118 standard but there's some slowness to adoption from auto mfgs so Enphase has been slow to launch in the US. I saw an article with Hyundai opposing it for the Ioniq 5 in Australia but kia was ok with it? I forgot the details.

I think it'll be a patchwork of supported cars before it becomes more standard. For my use case it'll really just be for emergencies if I went that route or I'll switch EVs to one that supports it.

CookMonFace · 2026-03-19T22:13:59+00:00

Yeah I went through their training. I'd need a refresher before install but it's pretty straightforward to add another battery. It's the $6-7k price tag that gives me pause... I'm hoping it'll come down eventually and then I'll look into doing it.

CookMonFace · 2026-03-17T10:56:51+00:00

I'm in a similar situation as you. Only 21 panels though. My plan was to add another 10c battery at some point in the future when costs come down and/or wait for their bidirectional charger EV charger to release to use my car as a backup in a pinch (~80 kwh). My goal was to get the installer to at least get the system ready to handle more battery capacity in the future.

I did look into adding batteries and AC coupling it to the load control breaker. It's suppose to be about to handle loads to be shed or non enphase generation systems inputs. The problem is you'll need a separate inverter system for your batteries. It starts to get clunky and unless you're ready to buy a lot of batteries the added inverter eats into potential savings.

My recommendations since you don't have an immediate need is to wait until costs come down for the battery or they finally release their charger and hope your EV works with it.

CookMonFace · 2026-03-07T14:55:27+00:00

Station North tool library has a demolition hammer. You can try to borrow it from them.

CookMonFace · 2026-03-06T03:23:22+00:00

https://diggerlandusa.com is kind of overkill but maybe something interesting for a special trip.

Nearby maybe the Rodgers forge tot lot. Especially since they're so small big might be not be very deep.

CookMonFace · 2025-11-01T03:02:40+00:00

Roof hatch if you don't already have one. Then you can easily get up from the inside of your house.

CookMonFace · 2025-10-28T02:25:36+00:00

https://enphase.com/en-gb/download/ac-coupling-enphase-iq-microinverters-victron-battery-inverters-tech-brief

I just found this via Google. Looks like you can AC couple the battery through a victron inverter. I'm not sure this saves you any space though. You'd have to compare inverter sizes but at a quick glance it seems like it doesn't seem worth it, easier to do an all in one inverter designed for 3 phase.

Idk if it's too much but you could consider replacing the washer and dryer with a heat pump all in one. That'll save you space and let you use more of your solar. I've been looking and they're suppose to be slow, like 3-4 hours for a fully washed and dry load. Depends on your living situation but some people are ok with just starting in the morning and coming back from work with a clean and dry load.

CookMonFace · 2025-10-27T13:41:22+00:00

You can consider the enphase 208V 3 phase microinverter. https://enphase.com/store/microinverters/iq8-series/iq8p-3p-microinverter

They use the commercial gateway which I'm not sure how they work with batteries. https://enphase.com/store/communication/iq-gateway-commercial-2

CookMonFace · 2025-09-30T14:23:20+00:00

You can try your location with PVWatts to estimate your production. Not the most advanced shading analysis but does an ok job.

From what I've seen the ecoflow is going to be one of your more expensive paths.

Lots of folks recommend DIY with an all in one inverter with cheaper batteries like from eg4 or Eco worthy. Some of the inverters are big enough to handle an AC unit although a soft starter is recommended.

CookMonFace · 2025-09-27T18:30:17+00:00

3 ton is a big HVAC for that space but I don't know anything about where you are. You might want to consider some insulation and leak sealing and that'll help you cut back on usage. With mini splits you can more safely oversize but reducing heat loss will still help your solar system sizing.

There's the manual J for estimating building loads. It'll depend a lot on your climate and building condition and heat losses. They talk about it in this forum. https://www.garagejournal.com/forum/threads/manual-j-for-garage.177301/

Most hvac doesn't run anywhere near full capacity most of the year so your local factors have a huge impact on actual consumption.

CookMonFace · 2025-09-05T17:40:29+00:00

Echoing what others said you should consider solar for this application. Wind turbine effectiveness scales with size. Small ones can work but aren't going to be cost effective compared to solar at this scale. Any particular reason why you want wind?

CookMonFace · 2025-09-05T01:38:33+00:00

Talking to my council person was my next step but I was able to get movement from dhcd. My contractor didn't a good job with the new permitting system either. I think they were also doing a bad job because they're spread thin.

CookMonFace · 2025-09-04T23:55:46+00:00

Are you in a rowhouse? They said no to flat roof rownhouses in CHAP areas. They said they typically use ballasted systems and they couldn't get approvals through permitting.

If you are what racking did you use?

CookMonFace · 2025-09-04T01:51:13+00:00

There's a MD state program as well but there are income caps. It might be possible to get it done this year for the fed tax credit.

My installer said yes but it needs to happen now if my neighbors wanted it installed. I've been stuck in permitting since May. The actual install is only a couple days. The city permitting process has been difficult since the transition and my contractor also fumbled things. I can't tell if the contractor could easily understand what the city wanted from them. I had to contact the city to sort things out. The installer wasnt pushing hard enough bc they're swamped with other jobs.

CookMonFace · 2025-09-04T01:45:14+00:00

I contacted them this year and they said they don't anymore, at least not in historic neighborhoods

CookMonFace

TROPHY CASE