With the solar industry booming, manufacturers and installers are racing to improve their products in every conceivable way: more efficient PVs; better inverter technologies; remote control, sensing, and automation; better energy-use reporting; smarter appliances; open systems integration; and a proliferation of grid-tied and off-grid configurations. One area that hasn’t gotten quite as much attention is the installation, which takes special training, and can be as much as 30-50% of the cost of the system.

Bay Area startup Armageddon Energy has a new angle with a patented product that GreenTech Media has dubbed “The Ikea of Solar”. The SolarClover snaps together in cute little 3-panel modules, each with its own inverter. Lightweight and easy to handle, these modules can fit “almost anywhere” as they say. That includes small areas of roof, or uneven roofs that wouldn’t accommodate larger arrays. Three of them (9 leaves), make a 1-kW system that’s enough to power most major appliances for an efficient household.

Dmitry Dimov and Mark Goldman, the founders of Armageddon Energy, helped us out with a few questions.

What is the SolarClover?

Dmitry: With the SolarClover, we tried to design an attractive, easy to install, affordable solar energy system. It features lightweight, high-efficiency hexagonal solar panels and a triangular rack that assembles in minutes. On the one hand, it gives consumers a fresh look and an affordable package; on the other hand, it is designed to be installed by contractors and tradesmen using the tools and training they already possess.

The SolarClover assembles as easily as Ikea's prefab furniture. The triangular frame snaps together at the corners and then is screw mounted to the installation surface. Each panel snaps onto the top and then clicks into place. Rounded corners make the assembly more comfortable to handle.

(To see it in action, visit the GreenTech Media’s documentary clip)

What’s so different about your product?

Dmitry: We use standard high-efficiency solar cells, the kind you find in traditional rectangular solar modules, but we replaced the glass topsheet with a high-tech polymer film (Tefzel, the polymer they used to create the Beijing Swim Cube) and added a lightweight rigid backpanel, which greatly reduces weight and allows us to easily create our hexagonal shape.

There are a couple of simplified solar assembly kits out there, but our configuration is uniquely attractive and easy to assemble – and we have been recently granted a design patent for it.

Is it true that any fool can stick it together?

Mark: We actually prefer that the do-it-yourselfers leave this one to the professional installers – climbing on a roof is not the safest thing you can do on a weekend – but the system does set up very quickly.  You can assemble the rack in literally a minute or two.  Finding rafters and attaching the system to a roof can be done very quickly by an experienced installer, as can running AC conduit to the service panel and performing the grid interconnection.

For comparison, a typical residential solar installation takes 3 men 3 to 5 days, for an average 5 to 7 kilowatt system.  Our system, which is 1 kilowatt AC, takes two men half a day.

What are the efficiencies compared to other solar products that are currently available?

Mark: We use high efficiency solar cells, such as Suniva’s new 19 % efficient cell, and the polymer films let slightly more light through than glass topsheets, so our efficiencies are better than most.

When can I get a SolarClover for my house?

Mark: Armageddon Energy expects the units to be commercially available by the end of this year.  The main question mark here is how quickly we get through UL testing, for those familiar with regulatory compliance.

Where did Armageddon Energy get its name? Are you preparing for the post-apocalypse?

Mark: We are preparing for the Apocalypse, which we believe will be sunny, beautiful and full of clean, fresh air.

[Editor's note: ROTFLMAO!]

How much does it cost? Your brochure says, “For the cost of a single high-end appliance” but let’s put that into perspective. A 1kW system will cover “all your major appliances” – let’s compare your product with a “typical” solar system including installation costs.

Mark: Our suggested retail pricing will be $8,500 installed for a 1 kW AC system consisting of three SolarClovers.  That puts us in line with the low side of installation costs for residential systems today, but at a much smaller scale – one need only purchase 1 kW instead of the 5 or 7 that’s usually necessary to get to that low cost per watt.

If any fool can install them, do you think renters could stick them on their roof and re-wire their appliances to use it, without even telling their landlord or PG&E? After all, rental property owners aren’t motivated to move to solar energy if their tenants are paying their own utility bills. And tenants aren’t going to shell out for an investment in someone else’s property unless they can take it with them when they leave.

Mark: More than tenants running wires to their circuit breakers, it’s more likely that property developers will add SolarClovers to their multi-tenant buildings and then simply recoup the cost like any other property improvement that allows them to command a higher rent – except now they’ll have a “green property” that they can promote.

And if being green doesn’t attract tenants, a small, peak-shaving system like this one will help insulate both landlords and tenants from painful utility bills in the summer [or painfully sudden utility rate increases, as occurred in 2001].  Whether it’s the landlord or the tenant paying for power, as the price of solar falls, you can bet that PVs will become a signal of lower utility bills – and ours will be right up there on the roof saying so.

While researching solar technologies, we at Green Compliance Plus heard from solar installers  who all seem to think that architects are hard to work with. So, we spoke with Fernando Valenzuela of Alter Systems in Berkeley about how to design a solar-ready home. Note that only about 5-10% of Alter Systems’ customers are owner/architect teams. Usually it’s the homeowners approaching them directly because they want to “go solar”.

So… why are architects hard to work with? “They have a groupthink… they like design, the look, but they don’t understand systems. They ask questions like ‘why can’t we use this roof’ without realizing that you can’t split up an array. Their projects aren’t always quick, either, and rebates that were designed for may be gone by the time the project gets through approval.”

Valenzuela went on to provide various design tips, as well as insights into new technologies, best-of-breed products, the difference between grid-tied and off-grid systems, costs and returns compared with conventional power, financing options, and the importance of grid parity.

Solar Design Tips for Architects

Consider building shape, roof planes, and orientation: With a remodel, people engage with an architect after the house is already built. It’s really best to take solar into account and design for it from the start. This may include choosing a lot or site that allows for a good solar orientation. Assuming that you do have some power to determine the shape of the building envelope, just make sure you include a nice un-shaded patch of south facing roof around 20 x 30 feet for your PV arrays. It goes without saying to consider proper solar orientation for the building, of course, if you have the option to do so.

Until recently, a single contiguous area was needed for solar arrays, and many products are still configured to work only if all the panels are installed together as a group. The panels should be tilted for maximum solar angle. Some panels lay flat and others can be tilted up; flat panels are aesthetically preferable and better for the neighbors’ attitudes.

Optimize roof tilt: The optimum tilt for the solar panels is your the latitude minus 15 degrees. In California, allow for a south or west facing planar area that is tilted around 20-22 degrees. Utility-scale projects and off-grid systems sometimes use solar tracking devices, but typically residential panels are mounted in a fixed position. The “solar window” is the maximum energy harvesting hours, between 9am and 3pm.

The sun's path across the sky changes according to season.

Assuming that you design includes panels that are built directly into the roof, your roof tilt will determine the panel tilt. “Not too steep, either, ” says Valenzuela. A 30 degree roof tilt is too steep – it’s much harder, and more dangerous, to install the panels. “It works your abs and butt!” laughed Valenzuela. And it’s not exactly “green design” when crews get injured, is it?

The roof tilt also depends on whether you have a grid-tied or an off-grid system, according to Valenzuela.

• Grid tied should be your latitude minus 15 degrees. Grid-tied systems are optimized for summer, because that’s when you’ll get the most energy out of the system, and thus you’ll get more money back at the end of each year.
• Off grid, on the other hand, should ideally be your latitude plus 15 degrees. For off-grid you maximize for winter, because you need the system working even in the worst-case scenarios so that you’re not left in the dark. Basically you want to make sure the system will produce in the winter months.

Allow space for conduits: If solar power is an afterthought, then you may have a visible exterior conduit, which can be less aesthetic than building it into the wall. If you put the conduit under the sheetrock it won’t even show on the outside. But even if you’re not installing solar today, you can accommodate future solar in the design.

Left, a typical retrofit requires routing the conduits wherever you can. Right, allowing a place for solar conduits that's built into the house allows flexibility for future solar.

Be careful with vent placement. “Don’t put vent pipes in the middle of a rooftop solar array. If the pipes stick up too far, they’ll get in the way of the PV panels.”

Make the roofing strong. Roofing should be 2 x 6 or 2 x 10 at 16″ on center for strength. Modern codes want 2 x 4 at 24″ across to conserve materials. If the span is too long, however, this doesn’t account for the weight of the people walking on it to do things like install solar panels. For this purpose, spans over 8 feet need thicker rafters. “We do a lot of retrofits,” says Valenzuela. “Old buildings in Berkeley for example are often 2 x 4 at 24 off center. For these, we may have to put in a brace.”

Keep basic sizing guidelines in mind. The amount of surface area you need for your PV panels depends on how effective the panels themselves are, and how much power the house requires. A rule of thumb might be 500-600 SF of roof (or other area) for the solar array to generate 5 – 7 kW. This covers a lot of places, even desert climates. “Even in the hotter parts of California, with heavy air-conditioning loads, it’s not too far off base,” according to Valenzuela.

Understand the racking systems. It’s good to understand how racking systems operate. “No roof penetrations” are needed. In the future, each panel may come with an independent energy panels with built-in inverters. Innovations include reduced installation time and cost.

Process

Choosing Your Solar Companies: A solar systems company is essentially a contractor/consultant who supplies, specifies, and installs systems. “If your client wants solar power for heating, cooling, electricity, or water heating, then you as the architect will need to establish a good relationship with a company that you can rely on to supply a well-designed system that is appropriate for the programmatic requirements of the home.”

“Try to work with a few solar systems companies that you know well, to get standard products and sizes for components. But don’t rely on just one company, because some companies are over-scheduled right now and orders are going unfulfilled.”

How Long Does It Take? Allow a month turnaround including all permits and paperwork such as rebates.

Customer Experience: So what happens when someone comes to you and says they’re ready to go solar? Here’s what your clients can expect.

1. Site evaluation. The solar consultant will most likely want to visit the house to inspect the roof area, shading, and electrical box. Some houses just aren’t suitable for solar. “Usually it’s a mounting problem,” says Valenzuela. A general rule of thumb for say a 1,200 – 2,000 SF house is to have flat or south facing roof around 20 x 30. Using micro-inverters helps reduce the amount of roof area that you need (read on for more information).
2. Proposal. Assuming the house will support a solar system, the owner gets a price proposal. “I have to ask why they’re doing it to figure out if it’s off-grid, grid-tied, or hybrid system. If they sign off, the paperwork starts.”
3. Permits and Rebates. Local permits for installing a solar system can take as little as a day or up to around 2 weeks depending on locale. The paperwork for tax rebate programs takes 2-3 weeks.
4. Installation. Alter Systems takes 2 days to install, but schedules for 4 days to allow for contingencies such as rain. The owners or occupants can continue to use the home and live in the home while the installation is ongoing.

Grid-Tied and Off-Grid Systems

One basic decision the owners must make is whether to tie their new solar arrays int the power grid. Grid-tied and off-grid systems are totally different animals in some important ways, but as solar power gains mainstream acceptance, it must also be able to integrate smoothly into mainstream infrastructures as well.

• Off-Grid systems are the classic “1.0″ of solar renewable energy. Although they tend to be associated in the U.S. with environmental activism, survivalist movements, and early-adopting technology buffs, they’re also essential in parts of the world where a centralized power infrastructure either doesn’t exist or isn’t reliable.
• Grid-Tied systems are mainly intended to reduce or eliminate energy bills, as in Net Zero homes. It’s a more mainstream market than either the early adopters or the green contingent. A main motivation is likely to be cost savings.

Although grid-tied systems are a newer concept, they are likely to be the wave of the future in industrialized countries. The components of a grid-tied solar system are the panel arrays, a power inverter to convert the direct current generated by the panels into the alternating current used by household appliances, a manual power disconnect, and of course the utility company’s usual infrastructure: the meter and switch box.

A grid-tied system is simple and straightforward. There is no need to store power onsite. Power generated is fed directly back into the grid, and home power needs are drawn also directly from the grid.

An off-grid system has more components, because of the onsite power storage requirement. In an off-grid system, the solar arrays feed into a combiner box which balances the inputs from each array. The combiner box combines or branches together the PV arrays/modules and then takes all the power through one set of leads to the charge controller. The controller makes sure your battery is charged correctly, and prevent over-charging.

The advantage to this type of off-grid configuration is the ease with which you can add supplemental power-generation systems such as microhydro or wind turbines. The goal of an off-grid system is to keep the batteries fully charged at all times. If there’s a grid tie-in, the battery won’t “sell” back to the grid unless it is already fully charged.

Which configuration you choose for your solar system depends on the reason why you’re going solar in the first place. Homeowners typically adopt a grid-tied system to save on energy bills, reduce their carbon footprint, and perhaps to show off to their neighbors. Valenzuela cites an estimate from the Journal of Assessors and Appraisers that for each dollar you can shave off your annual home operating costs, you add $20 to the property value.

According to Valenzuela, based on his experiences with his own customers, homeowners might choose off-grid because they’re in a remote area, and either it’s too expensive to bring the grid out there, or it exists but is not completely unreliable. “Some people do it because they hate public utility companies just on principle,” notes Valenzuela. “They’re also more likely to be DIY types who are comfortable assembling their own systems,” he adds.

An off-grid system includes an onsite storage battery. It's designed to be self-reliant. The homeowner can add a grid-tie option as shown above.

So what are the pros and cons of each type of solar configuration? Grid-tied systems require less equipment and employ simpler configurations; on the downside, they’re limited based on inverter sizes.

With off-grid systems, it’s easier to add supplemental renewable-energy systems on the side for things like wind or microhydro.

It's easier to add supplemental power generation systems to an off-grid system with its own battery storage.

Off-Grid for Villages: A typical residential home might need a 6kW system. For sites such as an army base, a remote ranger station, or a farm with multiple buildings, a system called AC coupling can deliver 20 kW or more. Basically it’s a way to create your own micro-utility company, and collect power from solar arrays on several buildings, using one central inverter (such as the Sunny Island off-grid inverter from SMA Solar Technology) and a central storage area. “This type of installation is very useful in places like the Caribbean, island countries or places without any infrastructure,” says Valenzuela.

Could you implement something like that in a city neighborhood, I wondered? A residential collective of some sort, for people who live in urban areas but still want to have totally independent self-generated power, and who want to pool their money to invest in economies of scale? “You’d have to do all your own wiring,” Valenzuela responded. “They’d have to be fairly close together.”

Well… with the geek factor in this area of the country, I wouldn’t be surprised if it’s already happening. After all, if a few homes drop off the grid on a single city block, how would we ever know?

Solar Grid Parity

I didn’t even know what this was, but with all the talk about the ROI of solar systems vs. fuel cells vs. high-efficiency but conventional systems, it’s a very important concept. Solar grid parity is a tipping point in the energy marketplace when the cost of energy production for solar power will be equal to or less than the cost of generating conventional, fossil fuel-based grid power.

A common comparison is dollars per watt or cost per kWh. U.S. average power prices for last year ranged from 5 – 15 cents per kWh, averaging roughly around 10-11% (businesses were 1 cent cheaper).

This number includes upfront investment in equipment although of course there’s debate over how to calculate it and when this momentous day will actually come. 2012 seems to be a common guess, although coincidentally that’s also the end of the world, according to the Mayan doomsday calendar).

Prediction: “a number of solar companies will hit a long-pursued industry target of $1 per watt by 2012.”  This “race towards $1 per watt” means that “within a few years solar panels will be able to generate electricity cheaper than the grid in many regions of the world.” (Sunnier regions have a bigger solar payoff, not surprisingly.)

Another claim is that we can reach 2012 grid parity in “almost half the US” and he also notes that there are several ways to calculate grid parity.

Even 4 years ago, solar was still pooh-poohed as a boutique technology for wealthy do-gooders or conspicuous consumers. But that was before tax rebates and stimulus dollars made it easier for new owners to “green” their homes. Other factors include improved component efficiency and a wider array of creative financing options such as these options from SunRun to purchase solar power as a service, to lease the equipment to the owner, or to help owners seek solar financing through local municipal programs.

So, is it a sure thing that in 2012 we’ll all be putting PG&E out of business? Doubtful, but there’s definitely a sense that price parity is coming, it’s just a matter of when. For example, higher interest rates could hurt financing, and if grid prices fall, parity won’t be reached nearly as soon. For those who prefer to focus on equipment efficiencies, there’s a rather geeky engineering article from BP Solar that discusses current and future efficiencies, including emerging new technologies such organic photovoltaics and nanocomposite solar cells.

The $1 per watt number is disputed as overly simplistic on one investor blog: “PV’s competiveness with the grid varies wildly based on the region… The idea that module prices need to come down to $1/W for solar to be competitive is misplaced at best” because “PV is already at or near parity with the grid in a number of markets”. This blog also includes a good discussion of calculating the cost of various types of conventional power, including nuclear.

Solar Financing Innovations

For homeowners who want to finance their solar installation, three good sources are:

• Tax rebates
• Municipal funding options through property taxes
• Bank loans

In the second case above, this is a plan being adopted in some localities such as Santa Rosa. Basically, the city obtains the funds for solar installations at a very low interest, say 3%. The city then loans it out to homeowners at a slightly higher but still reasonable rate, say 7%. The owner then pays back the loan in the form of an extra property tax surcharge every year. If the house is sold, the new owner is responsible for continuing those payments as part of the home’s property tax bill, and the new owner of course enjoys the reduced energy bills in the meantime.

“Some owners just pay for it with a credit card,” said Valenzuela. I can’t imagine plunking down $35-$60,000 on my card but then again, I can’t imagine watching the national average of television, either. “Every dollar decrease in operating cost adds an extra $20 in property value,” said Valenzuela, “but equity is fake money. So, we don’t include this increased equity on our cost/benefit analyses that we show customers in our proposals.”

New Solar Products

During the course of our conversation, Valenzuela mentioned some of his favorite new solar technologies. In no particular order, here they are.

Solar forced air heaters. These devices are installed on a south-facing wall or roof and are best used as a complement to other heating systems, a boost but not a replacement. They’re small and relatively efficient, at least compared to PVs. A single 8-foot panel is enough to heat a small room. They use no fuel and have no moving parts except a fan to draw cold air into the panel and push heated air out directly into the room. They don’t work as well on cloudy days, obviously. And you don’t even need fancy PVs or heat collectors: here are some ingenious DIY solar air heaters made from recycled aluminum cans.

This 8-foot solar wall air heater from ClearDome Solar in San Diego can heat up to 500 SF of residential space.

Micro-Inverters. Green Compliance Plus has mentioned the breakthrough of micro-inverters in a previous post – basically, by having separate inverters for every PV panel in a solar array, you can harvest more energy because shaded panels no longer bring down the performance of the entire array. One maker of micro-inverters is Enphase Energy. Valenzuela waxed almost poetic about Enphase products: “At the recent Green Building Expo, their booth was mobbed while the big players were empty!”

FLEXpower ONE Off-Grid Solution. Valenzuela made special mention of one particular product from OutBack Power called the FLEXpower ONE. He recommended this for total off-grid systems including smaller installations such as boats.

Xantrex XW Grid-Tied Solution. The Xantrex XW from Schneider Electric is recommended for homes that are grid-tied with a battery backup. “It’s not quite as flexible as the OutBack for very small installations, but it’s easier for designers, because it’s a high-quality product and you can scale it up,” says Valenzuela.

But what should architects really know? “Use Enphase!” says Valenzuela.

One of our Title 24 clients, Okamoto Saijo Architecture, recently completed a  $50M retrofit that included creating a 900-kW PV system that is currently one of the largest affordable-housing solar installations in the world. We interviewed one of the principal architects, Eric Saijo, about how the Crescent Park project went from his perspective. He was actually quite happy with the outcome, and after 4+ years of budgeting, negotiating with utilities, the project is completed.

Crescent Park, an affordable-housing solar retrofit by Okamoto Saijo Architecture.

How were you selected?

In the last 12 years we’ve done lots of affordable housing rehabilitation projects. In this day and age people get put into certain categories. We’ve developed a reputation.

Eric Saijo and Paul Okamoto of Okamoto Saijo Architecture, at one of their own project sites

It’s less glamorous, but that’s OK. This client had been working with another architect and the project got put on the back burner for half a year. In 2005, they came to us. We spent 2 years in design and documentation to figure out the project scope.

How was scope determined?

Identifying the budget is always a challenge. They had a wish list of many items, including PV for 100% of electrical needs. We did feasibility studies to analyze whether they had the budget for all the things they wanted to do: update kitchens, flooring, waterproofing. The solar portion was only one aspect.

You did a lot of analysis in addition to design.

We worked hand in hand with our contractor (Brandon Slater of West Coast Contractors) from Day 1 on pricing and budget.

What would you do differently next time?

A better question might be what have we learned? Let’s talk about this instead. We learned more about handling the specific challenges of pulling off a PV installation in a 40-year-old multi-building complex.

Okamoto Saijo Architecture has done "green" private residences as well as sustainable public housing.

We started off with plans for 100% of onsite electrical needs generated by PVs. Our solar engineer did a layout showing where we could put panels on all roofs, taking tilt and orientation into account for each building. We also had an idea of the number of kWh that we needed to generate. Then we could look at all the other constraints.

What were the other constraints?

Not enough roof area on the existing buildings, and existing building systems that were not designed for the structural loads of the panels and the installation process.

Are solar panels really that heavy?

No, but retrofitting existing buildings triggers all sorts of re-analyses, and one of these is to re-analyze for seismic load. Any building that’s 40 years old won’t pass today’s seismic code requirements. And any increase in load over 5% triggers this seismic analysis… it’s a huge limiting factor.

Most PVs get installed in a design-build fashion.

When installing panels, there should be no live load on the roof where the panels are… adding even a minuscule amount of weight can be a problem sometimes.

What was the problem with retrofitting to use existing equipment?

How to make the most of the existing electrical service equipment in a retrofit! The simplest thing to do for an individual building is to install a large PV system and replace all the service equipment and tie in the PV to the entrance panel breaker.

Connecting those beautiful photovoltaics to the public utility's metering and grid system can be a "non-trivial exercise".

The electrical code is written in such a way that PVs are considered a “load” meaning that you might have to up-size the service equipment. The secondary field lines from PG&E, with extra runs to each building, for 24 buildings on 6 acres… this becomes a huge cost.

However, the electrical code does allow for line-side tap between the meter and the main shutoff switch. The equipment is now 40 years old which the code still allows, but it is physically difficult to implement line-side taps. We had to persuade PG&E and the head building official to conceptually approve it.

The larger buildings had enough space in their service equipment to clamp onto existing conductors when we needed to do that. We had to modify the charge condition meter main shut off and route it through a new gutter. We could do new tap here. and then clamp to conductor.

UL certification was another issue. The existing equipment, being 40 years old, wasn’t UL fabricated. Small enough to service meter and switch board were separate pieces of equipment. When the contractor, the electrical building inspector, the electrician, and the solar engineer got together – it was a tense moment!

When architects and building inspectors meet…

The next challenge was getting our systems approved by PG&E. You have to get approval from your local utility in order to submit for solar tax rebates. A 900 kW system like this one must undergo review at PG&E’s engineering department. They analyze their own infrastructure, including their transformers and underground conduits. In this case, PG&E’s equipment was also 40 years old, and perhaps built to prior standards. It took them quite awhile to analyze our proposal.

At first, they rejected it and wanted us to pay to upgrade all the transformers serving the complex. This was due to a loophole in the agreement for rebate systems for PVs, which allow the utilities to charge the client for these upgrades.

But if the power is generated onsite, why do you need those transformers?

In the middle of the day in a residential complex, power will be flowing out towards the grid. Changes to the photovoltaic systems had to be calibrated on the utilties’ side as well as ours. They had to change their meters so they could spin backwards.

Is that a smart meter?

No. A smart meter is one which is read remotely. [Communication is essentially what makes a smart meter more intelligent than a dumb meter]

Does PG&E do enough to support people like you?

There are people in various departments who did. The engineers really got behind us and worked with us to MAKE it work. Then there are other departments. All of them get delayed for a number of months without clear explanation. It could just be under-staffing.

Here’s an example of the type of problem we had to solve together with PG&E engineering… in one area of our project, there were 5 buildings served by one transformer. At first the told us that we had to pay for a new transformer, as well as pay for new primary and secondary feed lines – this would cost $200K.

Naturally our client wasn’t happy. PG&E countered that they were concerned that the kW would bump up the voltage above what they’re legally required to keep it under. Then they said, “But.. if you set the trip point on the inverters down, then we’ll approve.”

Inverters are normally set to 132V and they wanted us to set them at 127V. The PG&E grid is 120-122V but it just happens to be high in this particular location. As we installed systems in those 5 buildings, the inverters started to trip off. We’re still negotiating with PG&E over what to do.

What would you do different?

I wouldn’t accept a trip point! It was a sign that PG&E has real concerns about its own systems, that they were worried about the potential for voltage to increase too high . Our solar engineer had never run into that before. It was a real learning experience!

Even a genius can have a learning experience.

At this stage, our client didn’t know yet how much financing they could get. The budget was still in flux, and they really weren’t willing to accept sudden new costs. Especially in large renovations, you have to hold a large contingency fund; with our project, those funds are now available for post-construction.

What do the residents think about it?

Affordable housing is a very complex thing in our society. These are extremely low-income people. I didn’t have much contact with them but my sense is that they are appreciative of the renovations that included window replacement and other building improvements which improved their comfort and quality of life.

Another affordable housing project from Okamoto Saijo Architecture, PositiveMATCH is an adaptive re-use of a historic building in San Francisco, serving women with HIV and their children.

The buildings were made more airtight, with better insulation, new windows. And… cleaning the duct work after 40 years most likely improved the air quality.

Drainage for the entire site was improved. It’s very close to the Bay, with a high water table, so flooding is a concern. The storm drains were constantly backed up prior to the renovation, and ground floor units had water infiltration. All of these measures made the units more comfortable.

Another private residential design from Okamoto Saijo Architecture, a passive-solar farmhouse in Napa, CA

We also worked with the client to improve the visual appearance of the buildings. New paint schemes, and individual colors for each building. Before that, all 26 buildings on 24 acres had been colored the same. How monotonous!

Of course the resident’s don’t pay their own electric bill. That’s usually the thrilling part for homeowners is seeing their utility bill reduced. In this case, our client financed the PVs because they also pay the utilities.

Financing was through bonds. Our client was not the original developer. The project was originally built by a market-rate developer together with HUD. Our client bought it later, around 20 years ago.

Net zero energy buildings produce more energy than they consume, and while they can function autonomously from the grid, they aren’t necessarily disconnected from it – they can use the connection to sell excess energy back to the utility companies. Sounds too good to be true? Can you really get paid to solarize your home? Well, David Knight from the Monterey Energy Group just might be able to help you get there. His take as an experienced engineer on which of these technologies really makes sense should carry a lot of weight with both designers and their clients.

David Knight outlined the latest in his Net Zero energy home projects for an audience of architects and builders at the AIA offices in San Francisco last Thursday. It’s unusual for a mechanical engineering to specialize in residential work, but he’s installed over 6,000 radiant heating systems. He did his first all-electric Net Zero Energy home 6 months ago and has completed 12 more in the past two months alone.

“The usual problems with alternative energy homes is that none of the subs talk to each other, and you really need to use a whole-house approach,” he said. “These projects need someone to fill the role as a coordinator, and that’s what we do.”

Can solar PV really produce enough power for an entire house? Yes it can, now. Solar technologies are improving, and buildings themselves are getting more efficient. The cumulative impacts of improvements in glazing, appliances, heating and cooling systems, etc. means that, according to Knight, that new buildings use half the energy that they did even 5 years ago. Even General Electric’s got a Net Zero home that uses hybrid energy sources.

Payback is another area that may be changing. Solar traditionally has been viewed as having a long payback period. However, California has highest energy rates in the country, and a tiered system where the more you use in a month, the more you pay per kWh, anywhere from 12 to 44 cents. Of course, this means that solar payback is that much faster.

And although the 2005 Title 24 code doesn’t give credits for solar-powered electric items like water heaters, the new 2008 Title 24 will. Currently, designs that call for electric heat or water heating take a huge hit in their compliance score, regardless of whether that electric power came from PG&E or from onsite energy production.

To size the power system, Knight goes through the home’s floor plan room by room to predict power usage for each appliance and for heating, cooling, and water heating as well. Exterior lights and devices are also factored in. With this information in hand, you can figure out the home’s projected power usage – and from that, you can figure out the square footage of the solar panels needed.

Knight’s approach is to balance the home’s projected energy consumption against its capabilities for onsite energy production. On the “consumption” side, factors such as better insulation or more efficient glazing act to  reduce consumption. On the “production” side, there are not just one, but several options, some of which can be used in combination.

Solar Thermal

Solar Thermal Panels

Solar Thermal is a good solution for swimming pools, but not necessarily for a home. The problem with Solar Thermal is there’s no way to store unused energy. And at the times you need it most, during the winter, is also when the sun’s power is the weakest and of the shortest duration. In order to take maximum advantage of the sun’s rays when the winter sun is low in the sky, the panels need a steep upward tilt, which can be an aesthetic problem. You need to have a sizeable onsite storage tank.

Grid-Tied Solar Electric

Built-in Solar Electric

Solar electric panels embedded in clay tile roofing

Grid-Tie Solar Electric systems can provide enough energy for the house’s needs, and can store unused energy for use at a future time or for resale back onto the grid. With a GTSE system, you get one bill a year (hopefully, a very small one). The panels can be low and flat against the roof, and no onsite storage is needed. They are easier to maintain than some other types of solar systems. There is no transmission loss, as with conventional power. Sized correctly and with enough roof space, they can indeed supply all of a home’s power needs. And because the panels can lie flat and don’t need to be tilted, they can even be built right into the roof to look like a skylight or other design feature.

PV Thermal

PV Thermal panels sit on a heat-collecting tray

Photovoltaic Thermal systems have PV panels on top of a flat thermal module that captures the superheated air and either turns it into hot water, or flows the warmed air through the house for heating. PV Thermal systems require an attic space with a south facing sloped roof.

Geothermal Heat Exchange

Geothermal heat exchange system

Geothermal Heat Exchange systems use buried coils of fluid to take heat from the earth, or put excess heat back into the ground.

• Pros: silent; good for larger homes.
• Cons: Expensive and complicated to install. They need a yard or other open area to bury the equipment in, making them less suitable for urban areas. And, California’s high energy prices means that their electric pumps can generate higher electricity costs.
• Mixed Blessings: They are better for colder climates than for California. There’s a tax credit for them, but David Knight believes it will be short-lived because it offers too much potential for cheating.

NZE systems cost about the same as LEED Platinum paperwork. And, while your mortgage interest is tax-deductible, your PG&E bill is not. So if you spend the money to upgrade your home, you can add the expenditures for new systems onto your mortgage for the portion that isn’t already covered by direct rebates.

A principal in a local architectural firm approached us for T24 on a new house in Sonoma County that he was designing for himself and his partner. They needed Title 24 documents for their permit submittal, but beyond that, he wanted to qualify for solar rebate credits through California’s New Solar Homes Partnership Program (NSHP). He also wanted the house to be as “green” as possible, just because.

What do we need to do to get a rebate through California’s New Solar Homes Program?

Part of qualifying for California New Solar Homes Partnership Program (NSHP) is that the home’s Title 24 must exceed the baseline by 15%. As it turns out, the New Solar Homes Program has two tiers. Tier 1 is 15%, and requires Energy Star appliances. Tier 2 is 35%, requires Energy Star appliances, and you must demonstrate a 40% reduction in cooling load, presumably recovered from solar energy.

Well, the two buildings together were 15%, not 35. The main house was passing with flying colors, but the guest house was just squeaking by. So the question was, whether and how to modify the design aggressively enough to qualify for the higher Solar Homes tier. Since NSHP is tied to Title 24, there was some confusion over which features counted in which program.

Lessons Learned

Photovoltaics don’t count towards Title 24, but solar hot water does. However, using Solar Water Heating yields only small gains in the Title 24 results, not enough to make a difference in the Solar Homes incentive. Even without regulatory gains, though, adding solar hot water is relatively inexpensive, while PVs for electricity are not.

We also noted that the Solar Homes incentive has diminishing returns in the upper tier, because photovoltaics are expensive to buy and install, and can take many years to yield meaningful savings. Photovoltaics do count towards the solar credit, at $2.50 per watt, or 1500 watts for $3750. An additional incentive of $3.50 per watt or another $5,250 is available if you go for Tier 2. So, a Tier 2 home with 1500 watts of PV paneling would get a $9,000 rebate. But… it would cost $18K for the panels, plus installation.

Do we need a HERS rater?

When specific items are installed (Ducting, Solar P-V, certain EER-rated equipment etc.), these must be verified by a HERS rater who is a certified inspector with CalCerts, CHEERS, etc. When you have solar water heating or photovoltaics, it must be verified by an inspector who is specifically approved for the California New Solar Homes Program (aka “Title 24 HERS rated”).

What appliances count towards this credit under Energy Star?
Windows, heaters, lighting, fridge, freezer, dishwashers, washers, and dryers can earn Energy Star. Water heaters can be rated as High Efficiency under the Energy Star system, but they don’t “count” here towards the NSHP credit.

Where do Energy Star appliances get factored in for Title 24 compliance?

Umm, nowhere. Don’t confuse Title 24 calculations with the NSHP incentive. However, EnergyStar appliances count for plenty of other things – LEED for Homes, GreenPoints (which is strongly encouraged in some jurisdictions). And, of course, they contribute towards lower energy bills.

How much do you want to spend to improve the design?

Generally, adding more thermal mass, using fewer square feet of glass, using ultra low E glass, and adding a thermal envelope will all contribute towards improved energy performance, and all of these items are factored into the Title 24 calculations. But get it in before August 1, when the 2008 Title 24 requirements go into effect that are 15% more efficient than the old Title 24. With this added restriction, the main house would still comply, but not a 15% anymore, and the guest would not pass.

It’s relatively easy to let the Sun make hot water for us. Yet, for many contractors, architects and developers, Solar Heated Domestic Water (SHDW) is one “low hanging fruit” that is largely ignored. The hot tickets which thrill us are new technologies like photo-voltaic power or maybe even solar thermal power generation, but solar domestic water heating seems “old fashioned” and is often the last thing that residential designers want to think about when designing a home. For me at least, it reminds me of the 1970’s, Woodstock, hippies, “getting back to the land”, etc.

But the real truth is that in the past 30 years, Solar Water Heating has blossomed and today it is a mainstream sustainable energy efficiency industry. It is time for a second look. Today, changing over to Solar Heated Domestic Water (SHDW) is one of the easiest, and least expensive ways to save energy costs and truly “green” up a design.

So, when your client wants a “SOLAR HOUSE” but gets blown away at the exorbitant cost of Photo-Voltaic (which even after the current “stimulus Package” rebates still costs a fortune, and the un-rebated portion has a 30 year pay-back) you can offer them Solar Heated Domestic Water as an honest solar system which is also inexpensive. Where P-V has a 5-19% efficiency, SHDW has a 50-70% efficiency. When clients start hearing 70% efficiency, they will suddenly get interested.

WHERE TO FIND OUT: There is a great series of Do-It-Yourself (DIY) articles, which architects will find useful in understanding what the general contractor’s solar installer sub is trying to accomplish. Go on line to Home Power Magazine and sign up for a one year E-subscription ($9.95).

Next, you can down load  several articles, which will tell you what you need to know. I especially liked the one on System Sizing and Payback as compared to Photo-Voltaic.

• PV vs Solar Water Heating: Simple Solar Pay Back.
• Sizing Solar Hot Water Systrems
• Solar Simplified Hot Water
• Solar Hot Water: A Primer
• Do-It-Yourself Tips for Solar Water Heat
• Single Tank Solar Water Systems

FINALLY: Look at the TAX CREDIT REBATES allowed for a solar water heating system as compared to any other water heating system.

• ELECTRIC WATER HEATERS: NO TAX CREDIT for conventional electric storage water heaters or electric tankless water.
• HEAT PUMP WATER HEATERS: There is a tax credit for electric heat pump water heaters for 2009 and 2010 for 30% of the cost, up to $1,500. ENERGY STAR qualified electric heat pump water heaters are expected to reach the market in late-2009.
• GAS, OIL & PROPANE WATER HEATERS: There are also tax credits for gas, oil and propane water heaters (30% up to $1,500 in 2009 & 2010).
• SOLAR WATER HEATERS: solar water heaters (30% of the cost, NO MATTER HOW MUCH IT COSTS (no upper limit), through 2016.